Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Jan 1997
Effects of tetrabenazine on methamphetamine-induced hyperactivity in mice are dependent on order and time-course of administration.
The ambulation-increasing effect of methamphetamine (MAP: 2 mg/kg s.c.) in mice persisted for about 3 h. Tetrabenazine (TBZ: 4 mg/kg s.c.), a depleter of monoamines from the cytoplasmic pool did not increase ambulation on its own. Pretreatment with TBZ at 1.5 h before administration of MAP inhibited the stimulant effect of MAP. ⋯ Further, the fact that neither TBZ administration following GBR-12909 pretreatment, nor oxypertine treatment following MAP pretreatment, elicited transient hyperactivity suggests that dopamine is involved in hyperactivity elicited by post-MAP treatment with TBZ. It is also suggested that inhibition of monoamine oxidase (MAO) by MAP and dopamine displacement by TBZ may be responsible for the transient stimulation produced by 3-6 h post-MAP treatment with TBZ. It is hypothesized that the MAO inhibitory action of MAP persists after cessation of its acute stimulant effect, possibly up to 6 h after administration.
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Pharmacol. Biochem. Behav. · Jan 1997
Nitric oxide synthase inhibition impairs delayed recall in mature monkeys.
The gaseous neuromodulator nitric oxide (NO) is formed in brain regions known to mediate learning and memory processes. In rodent models, pharmacologic inhibition of NO synthesis impairs such processes. In the present study, N omega-nitro-L-arginine methyl ester (L-Name), an inhibitor of the constitutive form of the NO synthetic enzyme, was administered to seven non-aged, mature monkeys (Macaca Fascicularis, Macaca Mulatta, and Macaca Nemestrima) trained to perform a delayed matching-to-sample task (DMTS). ⋯ The detrimental effects of the 25 mg/kg dose of L-Name on DMTS accuracy were completely blocked by concurrent administration of a mole-equivalent dose of the NO amino acid precursor L-arginine. As a whole, these data suggest that L-Name impairs processes involved in delayed recall in monkeys and that this impairment is associated with attenuated synthesis of NO. However, at higher doses (> or = 25 mg/kg) this impairment is associated with aversive effects of L-Name, possibly at both central and peripheral sites.
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A large percentage of newborns are exposed to pharmacological agents that affect the brain in connection with pain management during labor. The two most commonly used agents are meperidine, administered intravenously or intramuscularly, and bupivacaine, administered by the epidural route. Over the years, infant behavioral assessments have been used in the neonatal nursery to identify labor analgesia regimens with minimal impact on neonatal status. ⋯ Most of the assessments, including those of cognitive function, were not influenced by perinatal analgesia. However, these studies have confirmed the neonatal depressant effects of meperidine and have suggested that the course of behavioral maturation during certain periods of infancy is influenced by both meperidine and bupivacaine administration at birth. These effects could occur as a result of effects on vulnerable brain processes during a sensitive period, interference with programming of brain development by endogenous agents, or alteration in early experiences.
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Pharmacol. Biochem. Behav. · Oct 1996
Randomized Controlled Trial Clinical TrialMidazolam does not influence intravenous fentanyl-induced analgesia in healthy volunteers.
The effects of saline and intravenous midazolam (0.5, 1, and 2 mg per 70 kg) in combination with intravenous fentanyl (0.1 mg/70 kg) were examined on pain induced by a cold pressor test. Healthy volunteers (six females, six males) were enrolled in a prospective, double-blind, randomized, crossover trial in which mood and psychomotor performance were also examined. Five minutes and 135 min postinjection subjects immersed their forearm in ice cold water for 3 min while assessments of pain were recorded. ⋯ During the second immersion (approximately 2.5 h postinjection) pain ratings did not differ between the drug and saline conditions. Mood-altering and psychomotor-impairing effects of the drug combination were dose related. We conclude that midazolam at the doses and route of administration tested neither potentiates nor decreases the analgesia produced by fentanyl in a cold-pressor pain assay.
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Pharmacol. Biochem. Behav. · Jun 1996
Randomized Controlled Trial Clinical TrialLack of acute tolerance development to the subjective, cognitive, and psychomotor effects of nitrous oxide in healthy volunteers.
A crossover, double-blind trial was conducted using eleven healthy volunteers to determine whether and the degree to which acute drug tolerance occurred to the subjective, cognitive, and psychomotor effects of a range of subanesthetic nitrous oxide doses (0, 10, 20, 30, and 40%). There was little evidence of acute drug tolerance to the subjective measures or to the cognitive/psychomotor impairing effects of nitrous oxide at any of the concentrations tested over the course of the 120-min inhalation.