Pharmacology, biochemistry, and behavior
-
Pharmacol. Biochem. Behav. · Nov 1995
Antiepileptic drugs--their effects on kindled seizures and kindling-induced learning impairments.
Many epileptic patients suffer from cognitive impairments. These impairments may be a consequence of the epileptogenic process and/or antiepileptic medication. Kindling is considered a useful experimental model to investigate drug effects on both the convulsive component of epilepsy and related alterations at the behavioral level. ⋯ Dipropylacetate and phenobarbital suppressed the development of motor seizures and counteracted the learning deficit. Although ethosuximide had a clear effect on kindled seizures, the learning deficit occurred in kindled rats. This suggests that AEDs effects on kindled seizures are not correlated with the elimination of deficits in the field of cognition.
-
Pharmacol. Biochem. Behav. · Aug 1995
Response of kynurenine pathway enzymes to pregnancy and dietary level of vitamin B-6.
The kynurenine pathway of tryptophan metabolism produces several neuroactive metabolites including 3-hydroxykynurenine, kynurenic acid, and quinolinic acid. This pathway is sensitive to reductions in vitamin B-6 availability because two key enzymes, kynurenine aminotransferase (KAT) and kynureninase (KYNase), require pyridoxal 5'-phosphate. During pregnancy abnormal concentrations of kynurenine metabolites are also found. ⋯ In contrast, KYNase activities were significantly reduced by dietary restriction of vitamin B-6, and pregnant mice had significantly lower activity than nonpregnant controls for all but the highest dietary level of PN-HCl. These data show that pregnancy has a more pronounced effect on KYNase activity than vitamin B-6 restriction, and that the effects of pregnancy and diet are additive. The alteration in the kynurenine pathway in pregnancy is due to a reduction in KYNase activity, which is resistant to alleviation by vitamin B-6 supplementation.
-
Pharmacol. Biochem. Behav. · Jun 1995
Supersensitivity to opioid analgesics following chronic opioid antagonist treatment: relationship to receptor selectivity.
The effect of chronic opioid antagonist treatment on the analgesic potency of six opioid agonists was compared to changes in opioid receptor density and the selectivity of each agonist for mu (DAMGO), delta (DPDPE) and kappa (U69,593) opioid receptors. Mice were implanted SC with a 15-mg naltrexone or placebo pellet for 8 days. The pellets were removed and 24 h later, mice were sacrificed and binding studies were conducted, or mice were tested in analgesia (tail-flick) dose-response studies. ⋯ There did not appear to be an obvious relationship between receptor selectivity and the magnitude of supersensitivity. These studies indicate that supersensitivity occurs for a broad range of opioid analgesics following chronic opioid antagonist treatment in the mouse. However, the selectivity of these agonists for mu, delta, and kappa receptors does not appear to correlate with differences in supersensitivity.
-
Pharmacol. Biochem. Behav. · Nov 1994
Randomized Controlled Trial Clinical TrialEffects of naloxone on the subjective and psychomotor effects of nitrous oxide in humans.
The effects of naloxone on the mood-altering and psychomotor-impairing effects of nitrous oxide were examined in two studies. Each of the double-blind, randomized trials tested effects of three doses of naloxone or saline placebo during inhalation of 30% nitrous oxide in oxygen or 100% oxygen placebo. ⋯ Naloxone had no effects by itself in either experiment, and, for the most part, did not significantly interact with nitrous oxide-induced changes in mood or psychomotor performance. Naloxone, in doses of 10 mg or less, does not appear to affect the subjective and psychomotor effects of nitrous oxide.
-
Pharmacol. Biochem. Behav. · Sep 1994
Fluoxetine-induced inhibition of male rat copulatory behavior: modification by lesions of the nucleus paragigantocellularis.
In Experiment 1, the 5-HT uptake blocker fluoxetine (FLX; 20 mg/kg) reduced the proportion of sexually experienced male rats displaying ejaculations. Among those animals that did ejaculate there was an increase in intromission frequency (IF), ejaculation latency (EL), and postejaculatory interval (PEI) and a reduction in copulatory efficiency (CE) during the final copulatory sequence prior to sexual exhaustion. ⋯ When FLX was given to rats with PGi lesions, it did not influence the proportion of rats ejaculating nor did it alter IF, EL, or PEI during the final copulatory series prior to exhaustion. These findings suggest that the inhibitory influences of FLX on male rat copulatory behavior are mediated in part by the interaction of FLX with neurons originating in the PGi.