Lessened sensitivity to apomorphine induced hypothermia following prenatal exposure to phenobarbital

Pregnant HS/Ibg mice received phenobarbital in their food (3g/kg) on gestation days 9 through 18. This method of treatment has been shown to induce long lasting CNS and metabolic changes in the offspring including neuronal losses, ultrastructural abberations, induction of hepatic enzymes and behavioral changes; among them were the decreased CNS sensitivity to barbiturate and ethanol. As part of an investigation into the role of neurotransmitter receptors in the mediation of behavioral changes, 50-day-old offspring were injected with 1.0 or 2.0 mg apomorphine/kg and their rectal temperature was monitored. Prenatally treated offspring were less sensitive to the hypothermic effect of apomorphine than controls (P <.01). This effect was similar in females and males. It is therefore suggested that prenatal phenobarbital administration induced subsensitivity of the postsynaptic receptors that mediate apomorphine induced hypothermia.