Prepulse inhibition (PPI) is an operational measure of sensorimotor gating and is known to be reduced when the dopamine D2 receptor is activated. We used a rodent model of psychosis in which increases in dopamine D2 receptor sensitivity are produced through neonatal quinpirole (a dopamine D2 / D3 agonist) treatment to rats. Rats were administered quinpirole (1mg/kg) or saline from postnatal day (P) 1-21. Rats were raised to adulthood and tested on PPI. Results showed that neonatal quinpirole treatment produced a significant reduction in PPI, and nicotine exacerbated this reduction. This reduction was partially blocked by the nicotinic antagonist mecamylamine. Brain tissue was analyzed for regulators of G-protein signaling (RGS) and results showed that neonatal quinpirole significantly decreased RGS9, but increased RGS17 as compared to controls. These results appear to indicate that the G-protein couples more efficiently to the D2 receptor, and nicotine exacerbates PPI deficits in D2 receptor-primed rats.

Psychedelics are a subset of hallucinogenic drugs that exert their characteristic effects through agonist activity at the serotonin receptor 2A (5-HT2A). In this study, I aimed to characterize the modulatory role of the metabotropic glutamate subtype 2 receptor (mGluR2) in the 5-HT2A-specific rodent model of hallucinogenic action, head-twitch response (HTR). Secondly, I aimed to explore if 5-HT2A agonist-induced deficits in prepulse inhibition (PPI) of the startle response, an additional model of hallucinogenic action, could be produced in mice. Though 5-HT2A agonist-induced PPI deficits, which represent interruptions in normal sensorimotor gating, have been described in both rats and humans, attempts to translate this behavior to mice are rare. In contrast to prior gene knockout studies suggesting the mGluR2 is necessary for 5-HT2A agonist-induced HTR, mGluR2 knockout (Grm2-/-) mice still displayed HTR upon administration of the psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI). Additionally, DOI and lysergic acid diethylamide (LSD) produced unexpected improvements in PPI in male 126S6/Sv wild-type mice, depending on the experimental protocol used and the origin of the animals. Sex differences were observed as DOI-induced improvements in PPI were present in female 129S6/Sv mice of the same origin and tested with the same protocol as their male counterparts; this effect in females was absent in 5-HT2A knockout (Htr2a-/-) mice. The results of this study shed light on issues with replicability and reproducibility in science, the importance of highlighting the origin and background of animal subjects, and potential sex differences in hallucinogenic drug action.

Ovarian steroid hormones are neuroactive steroids with widespread actions in the brain, and are thus able to influence mood, behavior and cognition. In this thesis the effects of progesterone withdrawal and the direct effects of the progesterone metabolite allopregnanolone are evaluated. Allopregnanolone, through binding to the GABAA receptor complex, enhances inhibitory neurotransmission, thus exerting anxiolytic, sedative and antiepileptic effects. The acoustic startle response (ASR) is a withdrawal reflex evoked by sudden or noxious auditory stimuli, and can be measured in humans as an eye blink. ASR is significantly increased in several anxiety disorders, and notably also during progesterone withdrawal. Sensorimotor gating can be assessed by measuring prepulse inhibition of the startle response (PPI). The CNS circuits regulating PPI are sensitive to hormone fluctuations. GABAergic drugs are involved in cognitive impairment and animal studies have indicated that allopregnanolone may inhibit learning. The main purpose of this research was to evaluate the behavioral effects of progesterone withdrawal on the startle response and sensorimotor gating in PMDD patients and healthy controls, in healthy third trimester pregnant women and healthy postpartum women. A second aim was to evaluate allopregnanolone effects on memory and cognition in healthy women and also on the startle response and PPI. We found that PMDD patients have an increased startle response across the menstrual cycle and a deficiency in sensorimotor gating during the late luteal phase. Ovarian steroids affect sensorimotor gating; pregnant women have lower levels of PPI than late postpartum women. Acutely administered allopregnanolone did not affect the ASR or PPI. Allopregnanolone impairs episodic memory in healthy women. In conclusion, our studies suggest that ovarian steroids, including allopregnanolone, do not influence the startle response. Ovarian steroids affect sensorimotor gating; pregnancy, a condition with high levels of ovarian steroids, suppresses PPI. Theoretically, the variability in PPI across reproductive events is due to effects mediated by the progesterone or estradiol receptors but is not mediated by allopregnanolone. PMDD patients display decreased PPI during the late luteal phase, suggesting underlying pathophysiology in common with other anxiety disorders. The most vulnerable memory system, the episodic memory, is impaired by the allopregnanolone in healthy women.

Methamphetamine (MA) abuse is a fast growing drug problem, and is the second most widely abused drug world-wide. MA abuse has been linked to the development of symptoms indistinguishable from schizophrenia, referred to as MA psychosis. MA abusing individuals, who most often comprise adolescents and young adults, are 11 times more likely than the general population to develop psychosis. Of further concern is that in utero exposure to MA is also a growing problem, with more women addicts choosing MA as their primary drug. This has significant implications for the neurodevelopment of the child, with subsequent behavioural deficits later in life. Epidemiological studies suggests that in utero or early life MA exposure places a vulnerable individual at greater risk for developing schizophrenia, although this has never been formerly studied either at clinical or pre-clinical level. Animal models of early life adversity, such as post-weaning social isolation rearing (SIR), can assist in understanding the underlying mechanisms in MA abuse and vulnerability to develop MA psychosis. The aim of the current study was to investigate the long term effects of either prenatal (in utero) or early postnatal administration of MA on the development of schizophrenia-like behavioural and neurochemical abnormalities later in life. In the in utero study, pregnant female Wistar rats received either saline (Sal) or MA 5 mg/kg/day for 16 days by subcutaneous (s.c.) injection , starting on prenatal day 13 (PreND-13) up to postnatal day 2 (PostND02). Male offspring were selected for the study. On PostND 21, the animals were weaned and reared under group or isolation reared conditions for 8 weeks. In the early postnatal study, adult male Wistar rats were divided into group reared and SIR conditions from PostND21. Either group received an escalating dose of MA twice a day (0.2 mg/kg – 6 mg/kg s.c.) or Sal for 16 days, from PostND35 to PostND50. Both in utero and early postnatal groups were then subjected to various behavioural tests on PostND78, including assessment of social interaction (SI) and prepulse inhibition (PPI) of acoustic startle. Following behavioural testing, rats were sacrificed and brains snap frozen for later analysis of cortico-striatal monoamine concentrations, superoxide dismutase activity and lipid peroxidation. In the prenatally exposed group no differences in %PPI was observed, although group reared animals receiving MA and SIR animals receiving Sal or MA showed a decrease in social interactive behaviours, including approaching, time together and anogenital sniffing. SIR animals receiving Sal or MA also showed a decrease in rearing. Regarding self-directed behaviours, group reared animals receiving MA and SIR animals receiving Sal or MA showed an increase in self-grooming. Although some disturbances in regional brain monoamines were observed in the frontal cortex and striatum across the groups, this did not reach significance. A significant increase in malondialdehyde was observed in the striatum in group reared animals receiving MA as well as SIR animals receiving Sal or MA, indicating cell damage, possibly of redox origin. In the early postnatal study, %PPI was significantly reduced in group reared animals receiving MA as well as in SIR animals receiving Sal or MA. Group reared animals receiving MA and SIR animals receiving Sal or MA showed a decrease in social interactive behaviours, including rearing, approaching, time together and anogenital sniffing. Regarding self-directed behaviours and locomotor activity, self-grooming and squares crossed was significantly increased in group reared animals receiving MA and SIR animals receiving Sal or MA. A significant increase in DA was evident in the frontal cortex of SIR and grouped housed animals receiving MA. DA in the MA + SIR combination was elevated but not significantly so. None of the treatments affected striatal monoamine levels. In the group reared animals receiving MA as well as the SIR animals receiving Sal or MA, a significant decrease in SOD activity was observed in the frontal cortex, indicating the presence of oxidative stress in this brain region. None of the parameters indicated an additive effect in MA + SIR treated animals. In conclusion, prenatal exposure to MA led to some evidence of late-life behavioural and neurochemical abnormalities akin to schizophrenia, confirming its penchant for psychotogenic effects. However, chronic postnatal MA exposure was more emphatic, being as effective as SIR, a neurodevelopmental model of schizophrenia, in inducing deficits in the above-mentioned behavioural and neurochemical parameters. Thus, early adolescent abuse of MA is a significant risk factor for the later development of schizophrenia or psychosis. However, the risk appeared not to be exacerbated in a population at risk, i.e. in SIR animals. / Thesis (MSc (Pharmacology))--North-West University, Potchefstroom Campus, 2013.

Purpose: Schizophrenia is a progressive degenerative illness that has been causally linked to mitochondrial dysfunction, oxidative stress and a pro-inflammatory state. Social isolation rearing (SIR) in rats models the neurodevelopmental aspects of schizophrenia. The antioxidant and glutamate modulator, N-acetyl cysteine (NAC), has demonstrated therapeutic potential in schizophrenia as adjunctive treatment, although this has not been tested in the SIR model. The purpose of this study was to assess whether SIR induces changes in mitochondrial function (adenosine triphosphate (ATP)), pro- vs. anti-inflammatory cytokine balance, tryptophan metabolism, a disturbance in cortico-striatal monoamines and related metabolites, and associated alterations in behaviors akin to schizophrenia, viz. social interaction, object recognition memory and prepulse inhibition (PPI). Moreover, I evaluated whether these bio-behavioral alterations could be reversed with sub-chronic clozapine, or NAC, and whether NAC may bolster the response to clozapine treatment. Methods: The objectives of the study were pursued through separately conducted studies. Male Sprague-Dawley (SD) rats (10 rats/group) were used in this study (Ethics number: NWU-0035-08-S5). Rats were randomly allocated to either social rearing or SIR for 8 weeks receiving either no treatment, vehicle, NAC (150 mg/kg/day), clozapine (5 mg/kg/day) or a combination of clozapine + NAC (CLZ + NAC) during the last 11 or 14 days of social rearing or SIR. After the 8 weeks, rats were tested for social interactive behaviors, object recognition memory and prepulse inhibition (PPI). Peripheral tryptophan metabolites (determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS)) and pro- and anti-inflammatory cytokines (IL-4, IL-6, TNF-α, IFN-γ) (enzyme-linked immunosorbent assay (ELISA)) were determined. Cortico-striatal ATP (bioluminescence assay) and monoamines (high performance liquid chromatography (HPLC)) were also determined. Results: SIR-induced significant deficits in social interactive behaviours, object recognition memory and PPI, associated with increased peripheral kynurenine, quinolinic acid (QA), and pro-inflammatory cytokines, as well as a decrease in kynurenic acid (KYNA), neuroprotective ratio and anti-inflammatory cytokines. I also observed an increase in striatal, but reduced frontal cortical ATP, dopamine, serotonin as well as their metabolites and noradrenaline’s metabolite, with noradrenaline increased in both brain regions in SIR rats. A separate dose-response study of NAC (50, 150, 250 mg/kg/day) found 150 mg/kg to be the most appropriate dose for the NAC and CLZ + NAC studies. Clozapine, NAC as well as CLZ + NAC reversed all these changes, with NAC being less effective than CLZ alone. CLZ + NAC was found to be more effective than clozapine alone in reversing certain bio-behavioral alterations induced by SIR. In addition NAC alone dose dependently reversed most of the SIR induced alterations. Conclusion: SIR induces behavioral alterations, a pro-inflammatory state, mitochondrial dysfunction and cortico-striatal monoamine alterations, closely resembling evidence in schizophrenia. Importantly, all these bio-behavioral alterations were reversed with clozapine, NAC and CLZ + NAC treatment. However, CLZ + NAC was more effective than clozapine alone in reversing some bio-behavioral alterations, supporting the therapeutic application of NAC as adjunctive treatment in schizophrenia. In addition, NAC dose dependently reversed SIR-induced cortico-striatal serotonin, noradrenaline and metabolites, emphasizing NAC’s potential use in other anxiety and stress- related disorders. / Thesis (PhD (Pharmacology))--North-West University, Potchefstroom Campus, 2013

Methamphetamine (MA) abuse is a fast growing drug problem, and is the second most widely abused drug world-wide. MA abuse has been linked to the development of symptoms indistinguishable from schizophrenia, referred to as MA psychosis. MA abusing individuals, who most often comprise adolescents and young adults, are 11 times more likely than the general population to develop psychosis. Of further concern is that in utero exposure to MA is also a growing problem, with more women addicts choosing MA as their primary drug. This has significant implications for the neurodevelopment of the child, with subsequent behavioural deficits later in life. Epidemiological studies suggests that in utero or early life MA exposure places a vulnerable individual at greater risk for developing schizophrenia, although this has never been formerly studied either at clinical or pre-clinical level. Animal models of early life adversity, such as post-weaning social isolation rearing (SIR), can assist in understanding the underlying mechanisms in MA abuse and vulnerability to develop MA psychosis. The aim of the current study was to investigate the long term effects of either prenatal (in utero) or early postnatal administration of MA on the development of schizophrenia-like behavioural and neurochemical abnormalities later in life. In the in utero study, pregnant female Wistar rats received either saline (Sal) or MA 5 mg/kg/day for 16 days by subcutaneous (s.c.) injection , starting on prenatal day 13 (PreND-13) up to postnatal day 2 (PostND02). Male offspring were selected for the study. On PostND 21, the animals were weaned and reared under group or isolation reared conditions for 8 weeks. In the early postnatal study, adult male Wistar rats were divided into group reared and SIR conditions from PostND21. Either group received an escalating dose of MA twice a day (0.2 mg/kg – 6 mg/kg s.c.) or Sal for 16 days, from PostND35 to PostND50. Both in utero and early postnatal groups were then subjected to various behavioural tests on PostND78, including assessment of social interaction (SI) and prepulse inhibition (PPI) of acoustic startle. Following behavioural testing, rats were sacrificed and brains snap frozen for later analysis of cortico-striatal monoamine concentrations, superoxide dismutase activity and lipid peroxidation. In the prenatally exposed group no differences in %PPI was observed, although group reared animals receiving MA and SIR animals receiving Sal or MA showed a decrease in social interactive behaviours, including approaching, time together and anogenital sniffing. SIR animals receiving Sal or MA also showed a decrease in rearing. Regarding self-directed behaviours, group reared animals receiving MA and SIR animals receiving Sal or MA showed an increase in self-grooming. Although some disturbances in regional brain monoamines were observed in the frontal cortex and striatum across the groups, this did not reach significance. A significant increase in malondialdehyde was observed in the striatum in group reared animals receiving MA as well as SIR animals receiving Sal or MA, indicating cell damage, possibly of redox origin. In the early postnatal study, %PPI was significantly reduced in group reared animals receiving MA as well as in SIR animals receiving Sal or MA. Group reared animals receiving MA and SIR animals receiving Sal or MA showed a decrease in social interactive behaviours, including rearing, approaching, time together and anogenital sniffing. Regarding self-directed behaviours and locomotor activity, self-grooming and squares crossed was significantly increased in group reared animals receiving MA and SIR animals receiving Sal or MA. A significant increase in DA was evident in the frontal cortex of SIR and grouped housed animals receiving MA. DA in the MA + SIR combination was elevated but not significantly so. None of the treatments affected striatal monoamine levels. In the group reared animals receiving MA as well as the SIR animals receiving Sal or MA, a significant decrease in SOD activity was observed in the frontal cortex, indicating the presence of oxidative stress in this brain region. None of the parameters indicated an additive effect in MA + SIR treated animals. In conclusion, prenatal exposure to MA led to some evidence of late-life behavioural and neurochemical abnormalities akin to schizophrenia, confirming its penchant for psychotogenic effects. However, chronic postnatal MA exposure was more emphatic, being as effective as SIR, a neurodevelopmental model of schizophrenia, in inducing deficits in the above-mentioned behavioural and neurochemical parameters. Thus, early adolescent abuse of MA is a significant risk factor for the later development of schizophrenia or psychosis. However, the risk appeared not to be exacerbated in a population at risk, i.e. in SIR animals. / Thesis (MSc (Pharmacology))--North-West University, Potchefstroom Campus, 2013.

Purpose: Schizophrenia is a progressive degenerative illness that has been causally linked to mitochondrial dysfunction, oxidative stress and a pro-inflammatory state. Social isolation rearing (SIR) in rats models the neurodevelopmental aspects of schizophrenia. The antioxidant and glutamate modulator, N-acetyl cysteine (NAC), has demonstrated therapeutic potential in schizophrenia as adjunctive treatment, although this has not been tested in the SIR model. The purpose of this study was to assess whether SIR induces changes in mitochondrial function (adenosine triphosphate (ATP)), pro- vs. anti-inflammatory cytokine balance, tryptophan metabolism, a disturbance in cortico-striatal monoamines and related metabolites, and associated alterations in behaviors akin to schizophrenia, viz. social interaction, object recognition memory and prepulse inhibition (PPI). Moreover, I evaluated whether these bio-behavioral alterations could be reversed with sub-chronic clozapine, or NAC, and whether NAC may bolster the response to clozapine treatment. Methods: The objectives of the study were pursued through separately conducted studies. Male Sprague-Dawley (SD) rats (10 rats/group) were used in this study (Ethics number: NWU-0035-08-S5). Rats were randomly allocated to either social rearing or SIR for 8 weeks receiving either no treatment, vehicle, NAC (150 mg/kg/day), clozapine (5 mg/kg/day) or a combination of clozapine + NAC (CLZ + NAC) during the last 11 or 14 days of social rearing or SIR. After the 8 weeks, rats were tested for social interactive behaviors, object recognition memory and prepulse inhibition (PPI). Peripheral tryptophan metabolites (determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS)) and pro- and anti-inflammatory cytokines (IL-4, IL-6, TNF-α, IFN-γ) (enzyme-linked immunosorbent assay (ELISA)) were determined. Cortico-striatal ATP (bioluminescence assay) and monoamines (high performance liquid chromatography (HPLC)) were also determined. Results: SIR-induced significant deficits in social interactive behaviours, object recognition memory and PPI, associated with increased peripheral kynurenine, quinolinic acid (QA), and pro-inflammatory cytokines, as well as a decrease in kynurenic acid (KYNA), neuroprotective ratio and anti-inflammatory cytokines. I also observed an increase in striatal, but reduced frontal cortical ATP, dopamine, serotonin as well as their metabolites and noradrenaline’s metabolite, with noradrenaline increased in both brain regions in SIR rats. A separate dose-response study of NAC (50, 150, 250 mg/kg/day) found 150 mg/kg to be the most appropriate dose for the NAC and CLZ + NAC studies. Clozapine, NAC as well as CLZ + NAC reversed all these changes, with NAC being less effective than CLZ alone. CLZ + NAC was found to be more effective than clozapine alone in reversing certain bio-behavioral alterations induced by SIR. In addition NAC alone dose dependently reversed most of the SIR induced alterations. Conclusion: SIR induces behavioral alterations, a pro-inflammatory state, mitochondrial dysfunction and cortico-striatal monoamine alterations, closely resembling evidence in schizophrenia. Importantly, all these bio-behavioral alterations were reversed with clozapine, NAC and CLZ + NAC treatment. However, CLZ + NAC was more effective than clozapine alone in reversing some bio-behavioral alterations, supporting the therapeutic application of NAC as adjunctive treatment in schizophrenia. In addition, NAC dose dependently reversed SIR-induced cortico-striatal serotonin, noradrenaline and metabolites, emphasizing NAC’s potential use in other anxiety and stress- related disorders. / Thesis (PhD (Pharmacology))--North-West University, Potchefstroom Campus, 2013

GPR88 est un récepteur couplé aux protéines G orphelin exprimé principalement au niveau du striatum spécifiquement dans les neurones moyens épineux de la voie striato-nigrale et de la voie striato-pallidale.Premièrement nous avons étudié les souris Gpr88 KO et montré des altérations biochimiques, structurales et comportementales. Aussi les résultats montrent que l’hyperactivité des souris Gpr88 KO est diminuée par l’administration de méthylphénidate. Deuxièmement nous avons montré que la diminution des comportements liés à l’anxiété dépend de GPR88 dans la voie striato-pallidale et que la coordination motrice est régulée par GPR88 dans le striatum adulte (injection AAV-Cre) et dans la voie striato-pallidale. Dernièrement, nous avons confirmé un déficit d’inhibition du prépulse chez les souris Gpr88 KO, mais aussi montré que celui-ci s’étend à la modalité visuelle et n’est pas lié à un déficit général d’inhibition ou à la délétion de Gpr88 dans les neurones striato-pallidaux. / Among brain orphan G protein-coupled receptors, GPR88 shows high expression mainly in the striatum specifically in medium spiny neurons of both the striatonigral and striatopallidal pathwaysFirst, we examine full Gpr88 KO mice and show biochemical, structural and behavioral alterations. Results also show that the hyperactivity phenotype of Gpr88 KO mice is reversed by methylphenidate.Second, we show that Gpr88 in striatopallidal neurons (cKO approach) exerts anxiogénic activity and that motor coordination is regulated by GPR88 in the adult brain (AAV-Cre approach) and in the striatopallidal pathway.Finally, we confirmed previous data showing impaired acoustic prepulse inhibition in Gpr88 KO mice and further show that this deficit is not the result of a general inhibition deficit or of the lack of GPR88 in striatopallidal neurons.

Possible connection between latent toxoplasmosis and schizophrenia is a very interesting and medically important topic. In this thesis I tried to map current state of knowledge in the interdisciplinary research of schizophrenia and Toxoplasma gondii and their possible connections as well as to show differences in responses between Toxoplasma-positive and Toxoplasma-negative subjects using simple computer-administered tests of prepulse inhibition of startle reaction (PPI). Such differences would suggest another similarity between schizophrenia patients and subjects with latent toxoplasmosis as the sensorimotor gating responsible for PPI was found to be disrupted in schizophrenia patients. Side goal of the study was to test newly developed PC software for testing PPI and to determine its applicability in further research. Subjects for the tests were recruited among adepts of professional military service; 409 subjects completed the test of acoustic PPI and 276 subjects completed the test of visual PPI. All the subjects were tested on presence of specific anti-Toxoplasma IgG in their blood serum. Both tests revealed significant (p<0.001) differences between responses on prepulse-preceded stimuli and plain stimuli without prepulse, no significant results were, however, gained for the effects of latent...

Effects of Toxoplasmosis on Reaction Times and Prepulse Inhibition of Startle Reaction in Humans vi Abstract Toxoplasma gondii, a single-cell coccidia from almost exclusively parasitic phylum Apicomplexa, does not typically cause acute health issues in humans with most exceptions among immunodeficient individuals and pregnant mothers or, more precisely, their offspring. In the latent phase, the bradyzoites in tissue cysts placed most often in neural and muscle tissues can evolve pressure on the host's body both as a collateral effect of the presence of the parasitic organism in host's tissues and as a consequence of adaptive evolution leading to increase in probability of trophic transmission to the final host, a felid. In humans, this can result in slight changes in personality profiles, deterioration of psychomotor and cognitive functions, and development of serious mental disorders. The thesis focuses predominantly on one of the aspects of the changes, namely the effect of latent toxoplasmosis on the processing of startle signals themselves and when modified by a preceding low-intensity signal; this processing may be connected with the development of schizophrenia in predisposed individuals. Studies conducted within the project framework found changes int the speed of signal processing in...