Microarray analysis of gene expression in osteoblasts from patients with osteoporosis (OP) and osteoarthritis (OA) showed that 115 genes were robustly differentially expressed (P<0.05). Functional annotation clustering revealed cell adhesion to be the gene ontology classification most likely to be associated with this gene list. In addition scrutiny of the list revealed several genes with strong biological support for the involvement in bone homeostasis (FOSL1, BMPR2 and TGFBR1). Real -time PCR validated the trends seen in the microarray analysis, but failed to reach statistical significance for any of the genes examined. This analysis supports the value and potential of larger scale comparison of gene expression in OA and OP osteoblasts as a method for identifying novel factors involved in bone homeostasis. The cannabinoid system has recently been identified as involved in the regulation of bone homeostasis. In vitro investigation revealed that although cannnabinoid receptor agonists N-arachidonoylethanolamine (AEA), 2-arachidonoylglycerol (2-AG) and JWH015 had no effect on metabolic activity, cell number, or alkaline phosphatase activity of calvarial mouse osteoblasts there were changes in gene expression. RankL expression was reduced relative to Opg expression by both JWH015 and AEA. Preliminary results indicate that JWH015 was also capable of increasing PPARγ expression which could alter the balance of osteoblastic and adipocytic differentiation of mesenchymal stem cells (MSC). This could have implications for use of these drugs in vivo. Using the 3T3-F442A cell line to develop a model of MSC differentiation highlighted difficulties associated with using cell models. Necessary additional factors required to induce differentiation of a cell line compared to a primary cell make interpretation of results more complicated. This model also highlighted that alkaline phosphatase and osteocalcin (markers usually used to identify osteogenic differentiation) were expressed during adipocytic differentiation. Future use of such markers in MSC models should be closely scrutinized.

Here we demonstrate that both exogenous and endogenous cannabinoids affect different aspects of learning and memory in the rat.  For example, the potent CB₁ receptor agonist, WIN-2 was able to delay-dependently impair short-term memory (STM) sparing reference memory (RM).  This demonstrates that it is the STM but  not RM processes that are more sensitive to the effects of cannabinoids. In addition, given that cannabinoids were able to hinder the recruitment of hippocampal firing correlates that are crucial for correct performance of a STM task, suppress hippocampal principal cell firing during the encoding phase of a STM task, reduce spontaneous bursting and disrupt synchronous firing of hippocampal principal cells respectively, confirm that they do alter the neurophysiology of the hippocampus.  These cannabinoid induced alterations in hippocampal neuronal activity may well explain the observed deficits across numerous other working memory (WM) and STM tasks. The results also revealed that cannabinoid-induced deficits in learning and memory are brought about due to an interaction between cannabinoid and cholinergic systems.  Although endocannabinoids failed to produce impairments in STM under normal physiological conditions, STM deficits were observed when anadamide levels were pharmacologically elevated beyond normal physiological levels.  Moreover, results demonstrate that the endocannabinoid system is involved in behavioural flexibility (i.e. reversal learning) and modulation of acquisition and/or consolidation of certain spatial elements that are necessary to perform an operant conditioning risk. Overall, the results in this thesis show that cannabinoid induced deficits in learning and memory are produced as a result of their direct effects on hippocampal processing.  The exact mechanisms that mediate these cannabinoid-induced deficits in memory are yet unclear and remain to be determined.

No description available.

This study was directed at characterising the cannabinoid receptor activity modulating the electrical field stimulation (EFS) evoked contractions of the rat isolated ileum myenteric plexus longitudinal muscle (MPLM) preparation, and the capsaicin, nicotine and veratridine evoked secretory responses of the rat isolated colonic submucosal plexus-mucosal (SPM) preparation. EFS of the MPLM preparation with single pulses at a repetition frequency of 0.05 Hz elicited a transient twitch contraction immediately in response to each electrical pulse. In contrast, stimulation of the MPLM preparation with 2 second trains of pulses every minute at a frequency of 30 Hz elicited a rapid transient rebound contraction on termination of each train of EFS. The non-selective cannabinoid receptor agonists AEA, CP 55,940, D9-THC and WIN 55,212-2 inhibited both EFS-evoked twitch and rebound contractions of the rat ileum MPLM elicited by 0.05 Hz and 30 Hz EFS respectively. The inhibition of the twitch contractions was competitively antagonised by the cannabinoid CB1 receptor antagonist / inverse agonist SR 141716 with pKB values of 8.60. In contrast, SR 141716 only antagonised the ability of AEA, D9-THC and WIN 55,212-2 but not CP 55,940 to inhibit the rebound contractions with pA2 values of 6.60. These observations extended to the inhibitory effect of WIN 55,212-2 on the twitch and rebound contractions of the guinea-pig ileum MPLM. The CB2 antagonist / inverse agonist SR 144528 did not alter the effects of the agonists. Additionally, the inhibitory effect of AEA was refractory to the vanilloid TRPV1 receptor antagonist capsazepine. WIN 55,212-3 a stereoisomer of WIN 55,212-2 was without effect on the rat MPLM. SR 141716 alone concentration-dependently increased the twitch contractions but inhibited the rebound contractions. Both types of the EFS-evoked contractions were abolished by the Na+ channel blocker tetrodotoxin or the muscarinic acetylcholine (ACh) receptor antagonist atropine but not the nicotinic ACh receptor antagonist hexamethonium. None of the cannabinoids altered the contractions to exogenously applied ACh. These data suggested that the cannabinoid agonists inhibited the twitch contractions through a stereospecific presynaptic CB1 receptor-mediated reduction in the release of ACh. Additionally, the inhibition of the rebound contractions occurred because of an inhibition of ACh release by a novel stereospecific presynaptic non-CB1 -non CB2 -non -TRPV1 site. The ability of SR 141716 to inhibit the rebound contractions and antagonise AEA, D9-THC and WIN 55,212-2 may be though partial agonism at the non-CB1-non CB2-non-TRPV1 site. The ability of SR 141716 to potentiate the twitch contractions by increasing the release of ACh suggested that the CB1 receptor was constitutively active or was subjected to a tonic activation by endocannabinoid agonists. A comparison between the maximal enhancement of the twitch contractions of the rat and the guinea-pig ileum MPLM caused by three CB1 receptor antagonists/inverse agonists AM 251, SR 141716 and O-2050 showed that each cannabinoid had a different maximum. This suggested inverse agonism. These data were supported with studies showing the lack of effect of three fatty acid amide hydrolase (FAAH) inhibitors AA-5HT, PMSF, URB–597 and VDM-11, an inhibitor of the AEA uptake transporter on EFS-evoked contractions. These studies showed that all three FAAH inhibitors increased the potency of exogenously applied AEA but not WIN 55,212-2, and that VDM-11 had no effect on the potency of exogenously applied AEA. This data suggested that a functional endocannabinoid tone and the uptake transporter were not present in the MPLM, but FAAH was present. These data provide supporting evidence that SR 141716 behaved as an inverse agonist in the MPLM to augment twitch contractions. The interaction between CP 55,940 or WIN 55,212-2 with SR 141716 was investigated using the rat colonic SPM sheet. Both CP 55,940 and WIN 55,212-2 attenuated the secretory responses to capsaicin and nicotine in a SR 141716 sensitive manner. SR 140333, a neurokinin 1 receptor antagonist, abolished the capsaicin and nicotine. This suggested that CP 55,940 and WIN 55,212-2 inhibited the capsaicin and nicotine response through a CB1 receptor-mediated inhibition of the release of substance P or neurokinin A. The sensitivity of the veratridine response to TTX and a-chymotrypsin and the failure of the cannabinoids to attenuate the response suggested the absence of the CB1 receptor on the neurones releasing the undetermined neuropeptide. Together, these data suggest that both the CB1 receptor and non-CB1-non-CB2 -non-TRPV1 receptor can mediate the inhibitory effects of cannabinoid agonists in the rat ileum MPLM depending on the frequency of EFS. These data also show that SR 141716 is an inverse agonist in the MPLM. In the SPM preparation, the CB1 receptor appears to be involved in the modulation of some forms of peptidergic transmission.

The misuse of prescription opiates is on the rise with combination therapies (e.g. acetaminophen or NSAIDs) resulting in severe liver and kidney damage. In recent years, cannabinoid receptors have been identified as potential modulators of pain and rewarding behaviors associated with cocaine, nicotine and ethanol in preclinical models. Furthermore, activation of cannabinoid 2 (CB2) receptors on immune cells through the inhibition of monoacylglycerol lipase (MAGL), results in increased 2-arachidonylglycerol (2AG) production and analgesia in animal models. Yet, few studies have identified whether mu opioid and CB2 receptor agonists act synergistically to inhibit chronic pain while reducing unwanted side effects including reward liability, or if it could ameliorate the excruciating pain that is poorly managed with by opiates in bone cancer patients. We determined if analgesic synergy exists between the mu-opioid agonist morphine and the selective CB2 agonist, JWH015, or the inhibitor of MAGL, MJN110, in rodent models of acute and chronic inflammatory, post-operative, neuropathic, and cancer-induced bone pain (CIBP) using isobolographic analysis. We also investigated if the MOR-CB2 agonist combination decreased morphine-induced conditioned place preference (CPP) and slowing of gastrointestinal transit. Next, we examined whether JWH015 or the inhibition of MAGL decreased the release of pro-inflammatory mediators by activating nuclear factor kappa enhancer of activated B cells (NFkB), as dysregulation of NFkB is observed in various cancers. Here we show that MOR + CB2 agonism results in a significant synergistic inhibition of preclinical pain while significantly reducing opioid-induced unwanted side effects. The opioid sparing effect of CB2 receptor agonism strongly supports the advancement of a MOR-CB2 agonist combinatorial pain therapy for clinical trials.

Cannabis (known in its common forms as Cannabis sativa or Cannabis indica) is the most widely used illicit drug in the world and has been used for thousands of years for medicinal, religious and hedonistic purposes. In the last half of the 20th century the therapeutic uses of cannabis were largely ignored as most Western governments prohibited the use of the drug. Prohibition has come about largely as a result of the view that cannabis is a dangerous drug that poses major risks to both mental and physical health. However, this view is being increasingly challenged in recent years with a major popular movement towards decriminalization of cannabis occurring in some Western countries and a resurgence of interest in the medicinal properties of cannabis. Since Mechoulam and colleagues first isolated delta 9-tetrahydrocannabinol (delta 9-THC) as the main psychoactive constituent of cannabis, considerable advances have been made in the pharmacology of cannabis and cannabis-like drugs (cannabinoids). Central and peripheral cannabinoid receptors have been isolated and two endogenous ligands have been discovered. In addition, two cannabinoid receptor antagonists have been developed. However, our knowledge of the behavioural, neural and emotional effects of cannabis and the cannabinoids has often lagged behind our understanding of basic cannabinoid pharmacology. The present thesis attempts to further the understanding of the behavioural, neural and emotional effects of cannabinoids, using laboratory rats as subjects. A synthetic analogue of delta 9-THC (CP 55,940), is used as the primary pharmacological tool. The thesis offers a broad perspective with three major areas of investigation. These are: 1) the effects of CP 55,940 on anxiety-related behaviour (Chapters 2 and 3); 2) the effects of CP 55,940 on patterns of brain activation as indicated by c-fos expression (Chapter 4) and; 3) the addictive potential of CP 55,940 and its capacity to produce sensitization to the effects of other drugs such as cocaine (Chapters 5 and 6). A recurring theme throughout the thesis is that genetic factors may partially determine the behavioural, neural and emotional response to cannabinoids. To this end, the thesis compares Lewis and Wistar trains of rat in a wide variety of assays. Previous research has isolated Lewis rats as an "addiction-prone" and a "cannabinoid-preferring" strain, as they are more sensitive to the rewarding effects of various drugs of abuse including cannabinoids. Conversely, cannabinoids appear to have aversive effects in Wistar rats. A long-standing puzzle in cannabinoid research has been the question of why rats do not self-administer cannabis or cannabinoids. One likely reason is that cannabinoids have predominately aversive effects in rats. It is proposed here that these aversive effects arise because cannabinoids are anxiogenic agents in most rat strains. However some evidence indicates that the Lewis strain of rat are the only strain to find cannabinoids rewarding. It is hypothesised that Lewis rats may be more susceptible to the rewarding effects of cannabinoids because they are less susceptible to the anxiogenic effects of these compounds. In Chapters 2 and 3 the anxiogenic effects of the synthetic cannabinoid agonist CP 55,940 were compared in Lewis and Wistar rats in several different animal models of anxiety. In Chapter 2, the predatory odour avoidance, open area avoidance and conditioned ultrasonic vocalization (USV) models were utilised. In the predatory odour avoidance model, rats were exposed to cat odour in a rectangular arena and given the opportunity to hide in a small box. Both Lewis and Wistar rats displayed high levels of hiding during odour exposure. In Wistar but not Lewis rats, 50 �g/kg of CP 55,940 (i.p.) enhanced this avoidance response. Unfortunately, Lewis rats showed exceptionally high avoidance of the cat odour making it difficult to discern the effects of CP 55,940. To avoid this problem a second experiment was conducted, where rats were tested in the same arena as in the first experiment but with no cat odour present. Again in Wistar, but not Lewis rats, 25 and 50 �g/kg of CP 55,940 (i.p.) increased the avoidance of the open space. In the third experiment, Lewis and Wistar rats were placed in a chamber in which they had previously received footshock. Wistar but not Lewis rats re-exposed under the influence of 10, 25 or 50 �g/kg CP 55,940 (i.p.) emitted significantly more USVs than vehicle-treated rats. Thus, CP 55,940 clearly increased anxiety-related behaviour in Wistar rats but not Lewis rats, supporting the notion of a genetic predisposition towards cannabinoid-induced anxiety. In Chapter 3 the generality of the findings made in Chapter 2 were tested by utilising two further animal models of anxiety, the social interaction and light-dark emergence tests. From the results of Chapter 2, it could be claimed that Lewis rats were merely subsensitive to the effects of CP 55,940. Therefore a higher dose range (0, 25, 50 and 75 �g/kg i.p.) of CP 55,940 was employed in Chapter 3. In addition, the rotarod test was used to assess whether CP 55,940 has ataxic effects at these doses. In the first experiment, two unfamiliar rats were placed in a large arena and the time the rats spent socially interacting was recorded. CP 55,940 significantly reduced the total time rats spent socially interacting in Lewis (25 and 75 �g/kg) and Wistar rats (50 and 75 �g/kg). However, CP 55,940 has a significantly greater effect in Wistar rats compared to Lewis rats. In the second experiment, rats were placed in a small box within a large open arena and the latency to emerge from this box was measured. CP 55,940 increased emergence latency (at 75 �g/kg) and mean time per entry into the box (at 25 and 75 �g/kg) in Wistar but not Lewis rats. Furthermore, CP 55,940 caused a greater decrease in time spent in the open arena (at 25 and 75 �g/kg) and frequency of emergence (at 75 �g/kg) in Wistar rats in comparison to Lewis rats. In the third experiment, CP 55,940 (at 25, 50 and 75 �g/kg) caused mild incoordination only in Lewis rats as measured by the rotarod test. This finding argues against the assertion that the CP 55,940-induced anxiety-like behaviours in Wistar rats are merely a result of motoric impairment. Furthermore, it illustrates that Lewis rats are not generally subsensitive to the effects of CP 55,940. That is, when compared to other rat strains, Lewis rats may be more or less sensitive to the effects of CP 55,940 depending on what behaviour is being assessed. From the results of Chapters 2 and 3 it can be seen that Lewis rats are less sensitive to the anxiogenic effects of CP 55,940 than Wistar rats. In Chapter 4 it was hypothesised that in Lewis rats the effects of CP 55,940 on neural substrates of reward far outweigh the effects the compound has on neural substrates mediating anxiety. To examine this issue, the effects of CP 55,940 at a moderate (50 �g/kg i.p.) and high (250 �g/kg i.p.) dose were observed on c-fos expression (a measure of neural activation) and behaviour in Lewis and Wistar rats. CP 55,940 dose-dependently inhibited locomotor activity and reduced body temperature with Lewis rats being significantly less affected than Wistar rats. The 250 �g/kg dose caused significant catalepsy in both strains with a significantly greater effect in Wistar rats. These strain differences in the effects of CP 55,940 on body temperature and motor behaviour clearly correlated with c-fos expression in various regions and subregions. In general, Lewis rats showed significantly less Fos-labeled cells in comparison to Wistar rats. These strain differences in the effects of CP 55,940 on c-fos expression appeared unique to cannabinoids, as cocaine (15 mg/kg i.p.) had equivalent effects on c-fos expression in Lewis and Wistar rats. CP 55,940 promoted c-fos expression in areas not previously assessed, such as the median preoptic nucleus (MnPO), medial preoptic nucleus (MPO), anterior hypothalamic area (AH), islands of Calleja (ICjM), periaqueductal gray (PAG) and the pedunculopontine tegmental nucleus (PPTg). The strain differences uncovered in Chapters 2 and 3 correlated well with strain differences in the effects of CP 55,940 on c-fos expression in areas implicated in cannabinoid-induced anxiety, such as the central nucleus of the amygdala, bed nucleus of the stria terminalis, paraventricular nucleus of the hypothalamus and PAG. However, the effects of CP 55,940 on c-fos expression in a neural circuit which may underlie reward, which includes the shell of the nucleus accumbens (NAS) and PPTg, were also less in Lewis rats in comparison to Wistar rats. Future investigations must address whether the reduced effects of CP 55,940 on the Lewis rat are due to pharmacokinetics or pharmacodynamics. In addition, future studies must reconcile the pattern of c-fos expression observed here with prior reports of the Lewis rat being a unique "cannabinoid-preferring" strain. In Chapter 4, CP 55,940 administration promoted c-fos expression in areas of the brain thought to play a critical role in behavioural sensitization such as the ventral tegmental area and NAS. This is interesting because it is possible that c-fos is involved in promoting neuroadaptations that underlie drug addiction. To examine this idea, Chapter 5 investigated a behavioural assay of the long-term neural adaptations that may occur with the chronic administration of cannabis, namely, behavioural sensitization. This chapter also examined an animal model of the "gateway hypothesis", that is, the hypothesis that prior exposure to cannabis increases an individuals vulnerability to using other drugs. This animal model is known as cross-sensitization. First it was shown that Lewis, but not Wistar rats, given cocaine (15 mg/kg i.p.) every second day over a two week period displayed a progressively greater locomotor response to the drug over days indicating behavioural sensitization. When CP 55,940 (0, 10, 25 or 50 �g/kg i.p.) was administered under a similar regime, no such sensitization was observed in either strain. Rather, the two highest doses of CP 55,940 (25 and 50 �g/kg) caused locomotor suppression that lasted throughout administration. When Lewis or Wistar rats pre-exposed ten times to CP 55,940 were challenged with cocaine (15 mg/kg), no exaggerated locomotor response to cocaine was evident relative to non pre-exposed rats. When these rats were subsequently re-tested with CP 55,940, it continued to produce a dose-dependent suppression of locomotor activity. Finally, when CP 55,940 (50 �g/kg) was co-administered with cocaine in Lewis rats, it significantly reduced the locomotor hyperactivity produced by the drug but did not block the development of behavioural sensitization to cocaine. These results show that CP 55,940 does not sensitize locomotor activity with repeated administration in the same way as cocaine, and that pre-exposure or concurrent exposure to CP 55,940 does not enhance sensitivity to the subsequent behavioural effects of cocaine. Therefore, unlike Chapters 2, 3 and 4 where strain differences were observed in CP 55,940?induced anxiety, hypothermia, catalepsy, c-fos expression and ataxia, there were no strain differences with respect to behavioural sensitization. Landmark studies by Gardner and colleagues showed that Lewis rats are particularly susceptible, in comparison to other rat strains, to the rewarding effects of delta 9-THC on: 1) medial forebrain bundle (MFB) self-stimulation behaviour and; 2) dopamine (DA) efflux in the NAS. However, in Chapter 4 Lewis rats were less susceptible than Wistar rats to CP 55,940-induced c-fos expression in the NAS. Further, Lewis rats showed no behavioural sensitization to the chronic administration of CP 55,940. In light of these findings, Chapter 6 assessed whether CP 55,940 does have a rewarding effect on MFB self-stimulation behaviour in Lewis rats. Lewis rats were trained to self-stimulate the MFB using a rate?frequency paradigm and then administered CP 55,940 (0, 10, 25 and 50 �g/kg i.p.). CP 55,940 had no effect on MFB self-stimulation behaviour as assessed by the M50, the stimulation frequency at which half-maximal response rates were obtained. This result calls into question previous assertions that Lewis rats are a "cannabis-preferring" strain of rat. Previous studies utilising the cannabinoid CB1 receptor antagonist, SR 141716, have shown that the endogenous cannabinoid system may have some involvement in the rewarding effects of cocaine, morphine, sucrose and alcohol. Thus, Chapter 6 also assessed the effects of SR 141716 (0, 1, 3, 10 and 20 mg/kg i.p.) on MFB stimulation in Lewis rats. The role of DA in MFB stimulation reward has already been established, so for comparison purposes the effects of the DA D1 receptor antagonist SCH 23390 (0.06 mg/kg i.p.) was also assessed. Only a very high dose of SR 141716 (20 mg/kg) caused a significant inhibition of the rewarding efficacy of the stimulation with all other doses (1, 3, and 10 mg/kg) being ineffective in modulating the rewarding impact of brain stimulation. This was seen as an increase in M50. By comparison, a relatively low dose (0.06 mg/kg) of SCH 23390 caused a large increase in M50. These results indicate a relatively modest influence of the endogenous cannabinoid system on reward-relevant neurotransmission in the self-stimulation paradigm. Chapter 7 concludes the thesis and discusses the implications of the results obtained. The main findings of the current thesis are: 1) that the suggested "addiction-prone" Lewis strain of rat is less susceptible to cannabinoid-induced anxiety in comparison to Wistar rats; 2) Lewis rats show less cannabinoid-induced c-fos expression in comparison to Wistar rats (including in brain regions implicated in cannabinoid-induced anxiety and reward); 3) cannabinoid-induced c-fos expression exists in a number of brain regions never previously assessed such as the MPO, ICjM and PPTg; 4) behavioural sensitization does not occur with the repeated administration of CP 55,940; 5) cannabinoid pre-exposure or co-administration does not increase the sensitivity of the locomotor-activating effects of cocaine; 6) the endogenous cannabinoid system, at most, only has a minor influence on the neural substrate of brain stimulation reward and; 7) that there are previously unreported strain differences in cannabinoid-induced hypothermia, catalepsy and ataxia. These results add to our understanding of the effects of the behavioural, emotional and neural effects of cannabinoids and the endogenous cannabinoid system.

Marihuana continues to be a controversial topic in todays society. The plant material is used recreationally as a stupefacient and has a purported medicinal use. In fact, anecdotal information about its medicinal properties has been such that Health Canada has recently started an initiative to provide a well characterized supply of plant tissue to researchers interested in examining its potential medicinal properties. Simultaneously this same material is being provided for those subjects who are licensed to use marihuana as a medicine. <p>In order to further study marihuana and its component cannabinoids it is essential to be able to discern both the cannabinoid content in the product being supplied and more importantly the cannabinoid profile in the delivery system. At present the most common route of administration is via inhalation of the combusted plant material. Consequently methods capable of measuring the cannabinoid content in combusted plant material would be very useful in order to make meaningful study of the pharmacokinetics of the cannabinoids delivered by this route. <p>Investigations were carried out to develop a method and study the volatile constituents of combusted marihuana plant material in a semi-enclosed environment. Thus the hypothesis of this research is that qualitative and quantitative information can be obtained from the combustion products of cannabis plant tissue. The method relies upon the solid phase extraction of smoke arising from the combustion of plant material in a variety of combustion chambers. The combustion chambers were designed to reflect the current marihuana paraphernalia in use as well as a high efficiency in vitro system. Both the qualitative and quantitative levels of a limited number of cannabinoids were evaluated before and after combustion. A quantitative Liquid Chromatography Ultra Violet (LC-UV) detector method was validated for the analysis of a selected group of cannabinoids ( Δ9-tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD) and tetrahydrocannabinolic acid (THCA) . When this method was applied to plant material available through the medical marijuana initiative the following observations were made on the combustion products:<p> <table style="text-align: left; width: 397px;" border="1" cellpadding="2" cellspacing="2"> <tbody> <tr> <td style="width: 119px;">Material</td> <td style="width: 59px;">CBD</td> <td style="width: 59px;">CBN</td> <td style="width: 59px;">THC</td> <td style="width: 59px;">THCA</td> </tr> <tr> <td style="width: 119px;">Analyzed</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> </tr> <tr> <td style="width: 119px;">Plant</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">890</td> </tr> <tr> <td style="width: 119px;">Combusted</td> <td style="width: 59px;">20</td> <td style="width: 59px;">14</td> <td style="width: 59px;">420</td> <td style="width: 59px;">28</td> </tr> </tbody> </table> 5 mg plant tissue extracted using a validated HPLC-UV method <p> 5 mg plant tissue combusted in a closed combustion chamber.<p> BLQ: below level of quantification (<12.5 ug/mL)<p>These results sparked further research into the quantitative transformation of cannabinoids during the combustion process. In this regard, it was shown that THC, CBD and CBN all could be recovered at approximately a 90% ratio upon combustion However, THCA was thermally converted such that very little remains after combustion and furthermore, its degradation product, THC can only account for 50% of the THCA. The latter observation is important since there has been a prevailing thought that THCA is quantitatively transformed during combustion to THC while in fact this transformation is approximately 50%. This finding must be considered when pharmacokinetic studies are carried out using inhalation of combusted plant material as the delivery system.<p>A further finding of this research is that not all popular combustion devices yield identical quantitative cannabinoid profiles. In this regard, the simpler pipe systems result in the highest yields of heat transformed cannabinoids while the vaporizer systems have the lowest cannabinoid yields.

Marihuana continues to be a controversial topic in todays society. The plant material is used recreationally as a stupefacient and has a purported medicinal use. In fact, anecdotal information about its medicinal properties has been such that Health Canada has recently started an initiative to provide a well characterized supply of plant tissue to researchers interested in examining its potential medicinal properties. Simultaneously this same material is being provided for those subjects who are licensed to use marihuana as a medicine. <p>In order to further study marihuana and its component cannabinoids it is essential to be able to discern both the cannabinoid content in the product being supplied and more importantly the cannabinoid profile in the delivery system. At present the most common route of administration is via inhalation of the combusted plant material. Consequently methods capable of measuring the cannabinoid content in combusted plant material would be very useful in order to make meaningful study of the pharmacokinetics of the cannabinoids delivered by this route. <p>Investigations were carried out to develop a method and study the volatile constituents of combusted marihuana plant material in a semi-enclosed environment. Thus the hypothesis of this research is that qualitative and quantitative information can be obtained from the combustion products of cannabis plant tissue. The method relies upon the solid phase extraction of smoke arising from the combustion of plant material in a variety of combustion chambers. The combustion chambers were designed to reflect the current marihuana paraphernalia in use as well as a high efficiency in vitro system. Both the qualitative and quantitative levels of a limited number of cannabinoids were evaluated before and after combustion. A quantitative Liquid Chromatography Ultra Violet (LC-UV) detector method was validated for the analysis of a selected group of cannabinoids ( Δ9-tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD) and tetrahydrocannabinolic acid (THCA) . When this method was applied to plant material available through the medical marijuana initiative the following observations were made on the combustion products:<p> <table style="text-align: left; width: 397px;" border="1" cellpadding="2" cellspacing="2"> <tbody> <tr> <td style="width: 119px;">Material</td> <td style="width: 59px;">CBD</td> <td style="width: 59px;">CBN</td> <td style="width: 59px;">THC</td> <td style="width: 59px;">THCA</td> </tr> <tr> <td style="width: 119px;">Analyzed</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> <td style="width: 59px;">(ug/ml)</td> </tr> <tr> <td style="width: 119px;">Plant</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">BLQ</td> <td style="width: 59px;">890</td> </tr> <tr> <td style="width: 119px;">Combusted</td> <td style="width: 59px;">20</td> <td style="width: 59px;">14</td> <td style="width: 59px;">420</td> <td style="width: 59px;">28</td> </tr> </tbody> </table> 5 mg plant tissue extracted using a validated HPLC-UV method <p> 5 mg plant tissue combusted in a closed combustion chamber.<p> BLQ: below level of quantification (<12.5 ug/mL)<p>These results sparked further research into the quantitative transformation of cannabinoids during the combustion process. In this regard, it was shown that THC, CBD and CBN all could be recovered at approximately a 90% ratio upon combustion However, THCA was thermally converted such that very little remains after combustion and furthermore, its degradation product, THC can only account for 50% of the THCA. The latter observation is important since there has been a prevailing thought that THCA is quantitatively transformed during combustion to THC while in fact this transformation is approximately 50%. This finding must be considered when pharmacokinetic studies are carried out using inhalation of combusted plant material as the delivery system.<p>A further finding of this research is that not all popular combustion devices yield identical quantitative cannabinoid profiles. In this regard, the simpler pipe systems result in the highest yields of heat transformed cannabinoids while the vaporizer systems have the lowest cannabinoid yields.

Thesis (Ph. D.)--Open University. BLDSC no. DXN043607.

Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Physiology. Title from title-page of electronic thesis. Bibliography: leaves 145-[160].