Behavioural pharmacology
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Behavioural pharmacology · Feb 2002
Behavioural and pharmacological relevance of stroke-prone spontaneously hypertensive rats as an animal model of a developmental disorder.
The present study evaluates juvenile stroke-prone spontaneously hypertensive rats (SHRSP) as an animal model of a developmental disorder, which is diagnosed according to hyperactivity-impulsivity and/or inattention. To characterize behavioural alterations, we studied motor activity, as well as emotional and cognitive behaviours in juvenile SHRSP, with and without methylphenidate, a psychostimulant. Ambulatory and rearing activities in the open-field environment were significantly higher in SHRSP than in Wistar-Kyoto rats (WKY). ⋯ Our findings reveal that juvenile SHRSP manifest problematic behaviours resembling a developmental disorder, attention-deficit/hyperactivity disorder (ADHD), namely hyperactivity-impulsivity and/or inattention. Methylphenidate alleviated the behavioural symptoms of hyperactivity and inattention. We propose that juvenile SHRSP are an appropriate animal model of a developmental disorder resembling ADHD, from behavioural and pharmacological perspectives.
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Behavioural pharmacology · Dec 2001
Comparative StudyReceptor-selective antagonism of opioid antinociception in female versus male rats.
This study was conducted to determine whether sex differences in opioid antinociception may be explained by sex differences in opioid receptor activation. The time course, dose-effect and selectivity of antagonists that have been previously shown to be relatively mu (beta-funaltrexamine, beta-FNA), kappa (norbinaltorphimine, norBNI), or delta (naltrindole, NTI) receptor selective in male animals were compared in female and male Sprague-Dawley rats using a 52 degrees C hotplate test. In both sexes, beta-FNA (10 or 20 microg intracerebroventricularly [i.c.v.]) dose-dependently blocked the antinociceptive effects of fentanyl (0.056 mg/kg subcutaneously); antagonism was observed 24 h after beta-FNA, and diminished within 7-14 days. ⋯ The antinociceptive effect of the delta receptor-preferring agonist SNC 80 was significantly antagonized by NTI, but not by norBNI or beta-FNA, in both sexes. The sex difference in beta-FNA antagonism of morphine suggests that there may be sex differences in functional mu opioid receptor reserve or signal transduction; however, the lack of consistency across all mu agonists weakens this hypothesis. Overall, the opioids tested had very similar receptor selectivity in male and female subjects.
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Behavioural pharmacology · Apr 2000
The anticonvulsant compound gabapentin possesses anxiolytic but not amnesic effects in rats.
This report describes the effects of the antiepileptic agent gabapentin on anxiety and memory. Male Wistar rats received intraperitoneal administrations of gabapentin (10, 30 and 100mg/kg), diazepam (1 mg/kg), saline or diazepam vehicle 30 minutes prior to experimental procedures. ⋯ Memory was not affected by gabapentin in any of the tests, but was impaired by diazepam. The lack of effects of gabapentin on memory suggest a potential advantage of this drug over compounds with previously known anxiolytic property, which have amnesic effects at doses used for the treatment of anxiety disorders.
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Behavioural pharmacology · Feb 1998
Dopamine-dependent behavioural stimulation by non-peptide delta opioids BW373U86 and SNC 80: 1. Locomotion, rearing and stereotypies in intact rats.
The unconditioned behavioural effects of two non-peptide delta-opioid receptor agonists, BW 373U86 and SNC 80, were studied in the intact rat. BW 373U86 (0.1-2.5 mg/kg s.c.) and SNC 80 (2.5-10 mg/kg s.c.) dose-dependently elicited locomotion, rearing, stereotyped sniffing, licking and gnawing. These effects were abolished by pretreatment with the delta-opioid receptor antagonist naltrindole (5.0 mg/kg s.c.). ⋯ When higher doses of BW 373U86 were used (2.5 mg/kg), however, raclopride, even at high cataleptic doses (6.0 mg/kg), only partly prevented the behavioural stimulation induced by the delta-opioid receptor agonist. The behavioural stimulation remaining after high doses of raclopride was abolished by the administration of SCH 23390. These results show that delta-opioid receptor stimulation elicits dopamine-dependent behavioural activation in the rat that depends on dopamine receptors, particularly of the D1 subtype.
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Behavioural pharmacology · Dec 1997
Late and prolonged post-training memory modulation in entorhinal and parietal cortex by drugs acting on the cAMP/protein kinase A signalling pathway.
Rats implanted bilaterally with cannulae in the entorhinal or posterior parietal cortex or in the amygdaloid nucleus were trained in one-trial step-down inhibitory (passive) avoidance using a 0.3 mA footshock. At 0, 3, 6 or 9 h after training, they received localized 0.5 microliter infusions into these areas of a vehicle, or of 8-Br-cAMP, forskolin (adenylyl cyclase activator), KT5720 (protein kinase A inhibitor), SKF38393 (dopamine D1 receptor agonist), SCH23390 (D1 antagonist), norepinephrine hydrochloride, timolol hydrochloride (beta blocker), 8-HO-DPAT (5-HT1A receptor agonist) or NAN-190 (5-HT1A antagonist) dissolved in 20% dimethylsulfoxide (DMSO) in saline (vehicle). Rats were tested for retention 24 h after training. 8-Br-cAMP, forskolin, SKF 38393 and norepinephrine caused memory facilitation and KT5720, SCH23390, timolol and 8-HO-DPAT caused retrograde amnesia when given into the entorhinal cortex 0, 3 or 6 h but not 9 h after training. ⋯ The data point to a role of cAMP/protein kinase A-dependent mechanisms in memory formation in the entorhinal and parietal cortex, but not the amygdala, from 0 to 6 h after training, and to a strong modulation of these mechanisms by dopaminergic D1, beta-noradrenergic and 5-HT1A receptors. The lack of effect of NAN-190 but not 8-HO-DPAT in both cortical regions suggests that 5-HT1A receptors do not play a physiological role but can be activated pharmacologically. The fact that SCH23390 was amnestic but SKF38393 had no effect when given into the parietal cortex suggests that D1 receptors may play a maintenance rather than a stimulant role in this area.