Effect of acute and chronic morphine treatment on serotonin uptake into rat hypothalamic synaptosomes.

The effect of morphine on uptake of serotonin into hypothalamic synaptosomes was determined following acute and chronic morphine treatment in the rat. The uptake of serotonin was noncompetitively inhibited by in vitro morphine (IC50 = 7 X 10(-4) M) but not by an acute morphine treatment (30 mg/kg s.c.

Circadian rhythms in drug action and drug metabolism in the mouse.

The relationship between circadian rhythms in the pharmacological actions of meperidine and hexobarbital and similar rhythms in the hepatic metabolism of these drugs was examined in mice under a variety of environmental alterations to determine whether such rhythms may be causally related. The rate of metabolism of p-nitroanisole and hexobarbital by hepatic 9000 X g supernatant fractions was found to be higher at 2400 hours (middark phase) compared to 1200 hours (midlight phase). The rhythms in in vitro hexobarbital and in vivo merperidine metabolism were inversely related in time with similar rhythms in duration of hexobarbital sleep time and meperidine analgesia.

Similarity in cns sensitivity to hexobarbital in the rat and mouse as determined by an analytical, a pharmacokinetic, and an electroencephalographic measure.

Sensitivity of the central nervous system (CNS) to the hypnotic effect of hexobarbital was assessed by analytical, pharmacokinetic, and electroencephalographic techniques in male and female rats and in mice of both sexes by the first two techniques. These experimentally and conceptually diverse measures yielded strikingly similar estimates of CNS sensitivity to hexobarbital which was independent of both species and sex, while well known species ans sex (rat) differences in duration of response to hexobarbital were demonstrated.