Serotoninergic nerves are known to modulate sensitization of dopamine receptors (DA-R) in a rodent model of Parkinson’s disease (PD). However, serotoninergic nerves are not known to have a prominent role on DA exocytosis in intact rats. The current study was undertaken to explore the possible influence of serotoninergic nerves on DA exocytosis in Parkinsonian rats. Rat pups were treated at 3 days after birth with the neurotoxin 6-hydroxydopamine (6-OHDA; 134 μg icv, half into each lateral ventricle; desipramine, 1 h pretreatment), in order to produce marked long-lasting destruction of neostriatal dopaminergic innervation, as evidenced by the 90–95% depletion of DA (p < 0.001) [HPLC/ED] into adulthood. Controls received vehicle/desipramine in place of 6-OHDA. Other groups received the serotoninergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT; 25 μg base, icv, half in each lateral ventricle; desipramine, 1 h; 75 mg/kg pargyline HCl, 30 min) at 3 days post-birth; or both 6-OHDA+5,7-DHT treatments. In adulthood, an in vivo microdialysis study was undertaken to ascertain that p-chloroamphetamine (PCA, 1 mM in the microdialysate)-evoked DA release in the neostriatum was reduced approximately 50% in the 6-OHDA group, while PCA-evoked DA release in the 6-OHDA+5,7-DHT group was substantially increased, to a level equivalent to that of the vehicle control. The baseline neostriatal microdialysate level of 3,4-dihydroxyphenylacetic acid (DOPAC) was also higher in the 6-OHDA+5,7-DHT group vs 6-OHDA group; also, during the 2nd hour of PCA infusion. PCA-enhanced DA exocytosis occurred in the absence of changes in hydroxyl radical (HO·) in the microdialysate (i.e., assay of 2,3- and 2,5-dihydroxybenzoic acid, 2,3-DHBA; 2,5-DHBA). The overall findings demonstrate that an adulthood serotoninergic nerve lesion enhanced PCA-evoked DA exocytosis in a rodent model of severe PD, while susceptibility to oxidative stress was unchanged. The implication is that serotoninergic nerves may normally suppress the release of DA and/or act as an uptake site and storage sink for accumulated DA in parkinsonian-like neostriatum. Potentially, serotoninergic agonists or antagonists, targeting subtype-selective serotonin receptors, may be viable therapeutic adjuncts in PD.

The purpose of this study was to characterize a novel technique to study neurogenic control of cutaneous vasodilation. We monitored skin blood flow (SkBF) during in-vivo electrical stimulation (e-stim) intended to activate cutaneous nerves and used intradermal microdialysis to deliver receptor antagonists to characterize their contribution to cutaneous vasodilation. We examined the role of acetylcholine receptors (RACh), nitric oxide (NO), and vasoactive intestinal peptide receptors (RVIP) on the cutaneous vasodilation induced by e-stim in the absence of the sympathetic adrenergic nervous system. Six men and three women participated in the study. Three intradermal microdialysis probes were placed in the skin of the dorsal side of their forearm. The adrenergic nervous system was eliminated by delivery of a cocktail of phentolamine (0.01 mg/ml), propranolol (1 mM), and BIBP-3226 (10 µM). At one skin site atropine (0.1 mg/ml) was delivered to block RACh. At a second site we blocked nitric oxide synthase (NOS, 10 mM L-NAME) and RACh. Finally at the third site, we blocked RACh, NOS, and RVIP (0.47 mg/ml VIP10-28). The SkBF response to 1 minute stages of graded increases in frequency (0.2, 1, 2, 4, 8, and 32 Hz) at a current of 1.0 ± 0.1 mA was used to generate a stimulus-response curve before and after drug delivery. At skin site 1 RACh blockade decreased the area under curve (AUC) by 4% from 614 ± 279 to 591 ± 331 (p>0.05). Nitric oxide synthase and RACh blockade reduced the vasodilator response to e-stim by 23% from 1036 ± 457 to 801 ± 448 AUC (p>0.05). Combined NOS, RACh, and RVIP blockade reduced the vasodilator response by 48% from 802 ± 412 to 418 ± 268 AUC (p=0.07). RACh blockade had no effect on the vasodilator response to e-stim. However, in these preliminary studies both NOS and RVIP blockade provided some attenuation of the cutaneous vasodilator response associated with e-stim. Additional studies will focus on these two neurotransmitters as this novel method is refined. Advantages of e-stim include activating the sympathetic nervous system without activating local and humoral factors and studying neurotransmitters in an in-vivo setting during rest, thermal stress, or exercise.

Context: Low current intensity iontophoresis treatments have shown an increase in skin perfusion over 700% from baseline potentially increasing drug clearance from the targeted area. Objective: To determine the effects of a 10-minute ice massage on subcutaneous dexamethasone sodium phosphate (Dex-P) concentration and skin perfusion during and after a 4 mA iontophoresis treatment. Design: Controlled laboratory study. Setting: Research Laboratory. Patients or Other Participants: 26 individual participants (Males = 15, Females = 11, age = 25.6 ± 4.5 y, height = 173.9 ± 8.51 cm, mass = 76.11 ± 16.84 kg). Interventions: Participants were randomly assigned into two groups: 1) Pretreatment 10-minute ice massage; and 2) no pretreatment ice massage. Treatment consisted of an 80 mA min (4 mA∙20 minutes) Dex-P iontophoresis treatment. Microdialysis probes (3 mm deep in the forearm) were used to assess Dex-P, dexamethasone (Dex), and its metabolite (Dex-met) concentrations. Skin perfusion was measured using laser Doppler flowmetry probes. Main Outcome Measures: Microdialysis samples were collected at baseline, at conclusion of treatment, and every 20 minutes posttreatment for 60 minutes. Samples were analyzed to determine Dex-total concentration ([Dex-total] = Dex-P + Dex + Dex-met). Skin perfusion was calculated as a percent change from baseline. A repeated measures ANOVA was used for Dex-total and Skin Perfusion. Results: No significant difference was found in [Dex-total] between ice and no ice treatments, (P = 0.265). A significant increase in [Dex-total] occurred over the course of the iontophoresis and posttreatment time (P <<> 0.0004). Dex-P was recovered in 15 of 21 participants with a mean concentration of 0.604 ± 0.843 g/mL. Peak skin perfusion reached 27.74 ± 47.49% and 117.39 ± 103.45% from baseline for the ice and nonice groups, respectively. Conclusions: The 10-minute ice massage prior to iontophoresis does not significantly alter the delivery of [Dex-total] through the skin. A greater [Dex-P] was recovered than previously seen with lower intensities.

No description available.

No / Cortical spreading depression (CSD) is a temporary disruption of local ionic homeostasis that propagates slowly across the cerebral cortex, and may contribute to the pathophysiology of stroke and migraine. Previous studies demonstrated that nitric oxide (NO) formation promotes the repolarisation phase of CSD, and this effect may be cyclic GMP (cGMP)-mediated. Here, we have examined how phosphodiesterase (PDE) inhibition, either alone or superimposed on NO synthase (NOS) inhibition, alters CSD and the associated changes in extracellular cGMP. Microdialysis probes incorporating an electrode were implanted into the frontoparietal cortex of anaesthetised rats for quantitative recording of CSD, pharmacological manipulations, and dialysate sampling for cGMP measurements. CSD was induced by cathodal electrical stimulation in the region under study by microdialysis. Extracellular cGMP increased, but only slightly, during CSD. Perfusion of either zaprinast or sildenafil through the microdialysis probe, at concentrations that inhibited both PDE5 and PDE9 (and possibly other PDE), increased significantly extracellular cGMP. Unexpectedly, these levels remained high when NOS was subsequently inhibited with N¿-nitro- -arginine methyl ester hydrochloride ( -NAME, 1 mM). The most interesting pharmacological effect on CSD was obtained with sildenafil. This drug altered neither CSD nor the subsequent characteristic effect of NOS inhibition, i.e. a marked widening of CSD. The fact that NOS inhibition still widened CSD in the presence of the high extracellular levels of cGMP associated with PDE inhibition, suggests that NO may promote CSD recovery, independently of cGMP formation.

Yes / Here we describe for the first time the distinctive pharmacological profile for IRL752, a new phenyl-pyrrolidine derivative with regio-selective CNS transmission-enhancing properties. IRL752 (3.7-150 μmol/kg, s.c.) was characterised through extensive in vivo studies, using behavioural, tissue neurochemical and gene expression, as well as microdialysis methods. Behaviourally, the compound normalised tetrabenazine-induced hypoactivity, while unable to stimulate basal locomotion in normal animals or to either accentuate or reverse hyperactivity induced by amphetamine or MK-801. IRL752 induced but minor changes in monoaminergic tissue neurochemistry across NA- and DA-dominated brain regions. The expression of neuronal activity-, plasticity-, and cognition-related IEGs (immediate early genes) however increased by 1.5- to 2-fold. Furthermore, IRL752 dose-dependently enhanced cortical catecholamine dialysate output to 600-750% above baseline, while striatal DA remained unaltered and NA rose to ~250%; cortical and hippocampal dialysate ACh increased to ~250% and 190% above corresponding baseline, respectively. In line with this cortically preferential transmission-promoting action, the drug was also pro-cognitive in the novel object recognition and reversal learning tests. In vitro neurotarget affinity and functional data, coupled to drug exposure support the hypothesis that 5‑HT7 receptor and α2(C)-adrenoceptor antagonism are key contributors to the in vivo efficacy and original profile of IRL752. The cortical-preferring facilitatory impact on catecholamine (and ACh) neurotransmission, along with effects on IEG expression and cognition-enhancing features, are in line with the potential clinical usefulness of IRL752 in conditions where these aspects may be dysregulated, such as in axial motor and cognitive deficits in Parkinson's Disease.

Indiana University-Purdue University Indianapolis (IUPUI) / Research in the alcohol preferring (P) rat has indicated that peri-adolescent alcohol (EtOH) consumption enhances the acquisition of oral operant EtOH self-administration, inhibits the extinction of responding for EtOH, augments EtOH-seeking behaviors, and increases relative reward value of EtOH during adulthood. Experiment 1 was conducted to determine if these adult effects of peri-adolescent EtOH intake could be observed using an Intracranial Self-Administration (ICSA) model. It was hypothesized that an increased sensitivity to the rewarding actions of EtOH would be manifested in peri-adolescent-EtOH-exposed subjects compared to naive subjects when the opportunity to self-administer EtOH to the posterior ventral tegmental area (pVTA) is available in adulthood. The pVTA is a primary site for EtOH’s reinforcing and rewarding properties in the mesolimbic dopamine (DA) system. Experiment 2 was a dose-response examination of the effects of EtOH administered to the pVTA on downstream DA efflux in the nucleus accumbens shell (AcbSh) via a joint Microinjection-Microdialysis (MicroMicro) procedure. Male P rats were given 24-h free-choice exposure to 15% volume/volume EtOH from postnatal day (PD) 30 to PD 60, or remained experimentally naive, with ad lib food and water. By the end of the periadolescent exposure period, average consumption was 7.3 g/kg/day of EtOH. After PD 75, periadolescent-EtOH-exposed and naïve rats were either implanted with an injector guide cannula aimed at the right pVTA for ICSA (Experiment 1), or two cannulae, one aimed at the right pVTA (injector) and one at the ipsilateral AcbSh (microdialysis) for MicroMicro (Experiment 2). Following one week of recovery from surgery, ICSA subjects were placed in standard two-lever (active and inactive) operant chambers. Test sessions were 60 min in duration and occurred every other day for a total of 7 sessions. Rats were randomly assigned to one of 5 groups (n=4-9/group) that self-infused (FR1 schedule) either aCSF (vehicle, 0 mg%), 50, 75, 100, or 150 mg% EtOH during 4 sessions, aCSF only for sessions 5 and 6 (extinction), and the initial concentration again for session 7 (reinstatement). MicroMicro subjects received six days of recovery from surgery, probe implantation the day before testing, and then continuous microdialysis for DA with 15 min microdialysis samples collected before, during, and then two hrs after 10-min pulse microinjection of either aCSF (vehicle, 0 mg%), 50, 75, 100, or 150 mg% EtOH. Neither EtOH-exposed nor naive groups of P rats self-infused the aCSF or 50 mg% EtOH concentration. While the naive group did not self-infuse the 75 or 100 mg% EtOH concentrations, the peri-adolescent EtOH-exposed group of P rats did readily discriminate the active lever from the inactive lever at these concentrations. Both groups self-infused the 150 mg% EtOH concentration. Pulse microinjections of EtOH during the MicroMicro procedure revealed that 75 and 100 mg% concentrations of EtOH increased downstream DA in the AcbSh of EtOH-exposed, but not naïve, subjects. 150 mg% EtOH increased downstream DA in both adolescent treatment groups. Overall, the results indicate that consumption of EtOH by P rats during peri-adolescence increases the reinforcing properties of EtOH in the pVTA in adulthood. The results also indicate that there were differential effects of peri-adolescent EtOH exposure on DA efflux in the AcbSh. This provides evidence that peri-adolescent EtOH-exposure produces long-lasting alterations in neural circuitry involved in EtOH-reinforcement, during adulthood.

<p>During brain activity neurons release the major excitatory transmitter glutamate, which is taken up by astrocytes and converted to glutamine. Glutamine returns to neurons for re-conversion to glutamate. This glutamate-glutamine cycle is energy demanding. Glutamate turnover in injured brain was studied using an animal iron-induced posttraumatic epilepsy model and using neurointensive care data from 33 patients with spontaneous subarachnoid hemorrhage (SAH). Immunoblotting revealed that the functional form of the major astrocytic glutamate uptake protein GLT-1 was decreased 1-5 days following a cortical epileptogenic iron-injection, presumably due to oxidation-induced aggregation. Using microdialysis it was shown that the GLT-1 decrease was associated with increased interstitial glutamate levels and decreased interstitial glutamine levels. The results indicate a possible posttraumatic and post-stroke epileptogenic mechanism. Analysing 3600 microdialysis hours from patients it was found that the interstitial lactate/pyruvate (L/P) ratio correlate with the glutamine/glutamate ratio (r =-0.66). This correlation was as strong as the correlation between L/P and glutamate (r=0.68) and between lactate and glutamate (r=0.65). Pyruvate and glutamine correlated linearly (r=0.52). Energy failure periods, defined as L/P>40, were associated with high interstitial glutamate levels. Glutamine increased or decreased during energy failure periods depending on pyruvate. Energy failure periods were clinically associated with delayed ischemic neurological deficits (DIND) or development of radiologically verified infarcts, confirming that L/P>40 is a pathological microdialysis pattern that can predict ischemic deterioration after SAH. DIND-associated microdialysis patterns were L/P elevations and surges in interstitial glutamine. Glutamine and pyruvate correlated with the cerebral perfusion pressure (r=0.25, r=0.24). Glutamine and the glutamine/glutamate ratio correlated with the intracranial pressure (r=-0.29, r=0.40). Glutamine surges appeared upon substantial lowering of the intracranial pressure by increased cerebrospinal fluid drainage. Increased interstitial glutamine and pyruvate levels may reflect augmented astrocytic glycolysis in recovering brain tissue with increased energy demand due to a high glutamate-glutamine turnover.</p>

La mélatonine est connue pour agir directement sur l’horloge circadienne. L’agomélatine est un antidépresseur présentant des propriétés agonistes MT1/MT2 et antagonistes 5-HT2C. Tout d’abord, nous avons évalué les effets de l’agomélatine, de la mélatonine et d’un antagoniste 5-HT2C sur deux sorties de l’horloge (rythme de la mélatonine endogène et de la température corporelle). Les résultats obtenus suggèrent une action centrale de l’agomélatine et de la mélatonine, directement sur l’horloge via les récepteurs MT1/MT2, en induisant une augmentation de l’amplitude et une avance de phase du rythme de mélatonine. Pour la température corporelle, l’ensemble des drogues augmente l’amplitude du rythme, suggérant une action des propriétés agonistes MT1/MT2 et/ou antagonistes 5-HT2C de l’agomélatine. Puis, l’étude sur l’expression du gène horloge Per1, a révélé un effet supérieur de l’agomélatine par rapport à la mélatonine, mais seulement le jour du traitement. L’agomélatine pourrait agir sur la machinerie moléculaire de l’horloge, ce qui reste à exploiter davantage. Ces nouvelles données contribuent à une meilleure compréhension des mécanismes d’action de l’agomélatine. / Melatonin is known to act directly on the circadian clock. Agomelatine is an antidepressant with MT1/MT2 agonist and antagonist 5-HT2C properties. First, we evaluated the effects of agomelatine, melatonin and 5-HT2C antagonist on two clock outputs (rhythm of endogenous melatonin and body temperature). The results suggest a central action of agomelatine and melatonin, directly on the circadian clock via MT1/MT2 receptors, inducing an increase on the amplitude and a phase advance of the rhythm of melatonin. For body temperature, all drugs increased the amplitude of the rhythm, this suggest an action of MT1/MT2 agonist and antagonist 5-HT2C properties of agomelatine. Secondly, the study on the expression of clock gene Per1 revealed a greater effect of agomelatine compared to melatonin, but only on the day of treatment. Agomelatine could act on the molecular machinery of the clock, but requires further investigations. These new data allow a better understand of the mechanisms action of agomelatine.

Patienten mit zerebralen Läsionen, wie der aneurysmatischen Subarachnoidalblutung (SAB) und dem schweren Schädel-Hirn-Trauma (SHT), haben ein hohes Risiko für sekundäre Schädigungen des Gehirns aufgrund einer Minderdurchblutung (Ischämie) und einem Sauerstoffmangel (Hypoxie). Bei der SAB ist heutzutage die verlaufsbestimmende Komplikation das Auftreten einer Vasospasmus- assoziierten Ischämie, d.h. einer Minderdurchblutung aufgrund einer Gefäßverengung, die mit einer hohen Langzeitmorbidität mit schweren neurologischen Defiziten und einer hohen Mortalität assoziiert ist. Seit Beginn der 90er Jahre wird bei SAB- und SHT- Patienten das Mikrodialyseverfahren zur Messung des zerebralen Stoffwechsels eingesetzt und steht als Methode auf der Intensivstation seit 1997 zu Verfügung. Hierbei werden mittels einem, in das gefährdete Hirngewebe inserierten Katheter die extrazellulären Konzentrationen verschiedener Parameter gemessen. Patienten mit SAB weisen in Phasen einer klinischen Verschlechterung (z.B. Auftreten einer Lähmung) charakteristische Veränderungen des Hirnstoffwechsels auf. Vergleichsmessungen mit der Positronenemissionstomographie zeigen als mögliche Ursache für einen gestörten Hirnstoffwechsel einen erniedrigten zerebralen Blutfluß. Auch bei einer drohenden Hypoxie (Hirngewebe-PO2 < 10 mmHg) sind bereits metabolische Veränderungen zu beobachten. Die frühzeitige Erkennung und - wenn möglich - Behandlung einer Ischämie / Hypoxie könnte die Prognose von Patienten nach SAB und SHT wesentlich verbessern. / Patients with cerebral lesions run a high risk of developing cerebral hypoxic and ischemic damage due to secondary insults. To minimize the risk of secondary cerebral hypoxia and ischemia, new monitoring techniques of cerebral oxygenation and metabolism have been developed and may help to understand the pathophysiology of secondary brain damage for a better treatment and outcome in critical patients. Cerebral microdialysis is a relatively new technique for measuring brain molecules of the extracellular space. The technical aspects, the interpretation of the commonly measured parameters, the use of the commonly used oxygenation parameters (monitoring of brain tissue PO2 and the microdialysis technique to monitor cerebral metabolism) in patients with head injury and subarachnoid hemorrhage are considered. Pitfalls of the techniques and their future potential are discussed.