Inherited differences in plasma cyclic nucleotide levels of mice exposed to stress and treated with phenazepam

Abstract

Experiments were carried out on male B6 and C mice and their reciprocal F~ hybrids, weighing 18-20 g. The animals were kept under laboratory animal house conditions on a standard diet, with i0 mice per cage, 12 h of daylight and 12 h of darkness for 1.5 months before the experiment began. The open field test (OF) was used as model of emotional stress [2]. Phenazepam, in doses of 0.05 and 0.i mg/kg, was injected intraperitoneally 30 min before the experiment began. The concentrations of cA~ and cGMP were determined in the blood plasma by methods described previously [8, 15]. The initial level of the nucleotides (the animals were killed immediately after removal from the cage) and their concentrations 15 min after the experiment in OF (the OF + 15 series) were investigated. When the effects of phenazepam were analyzed, nucleotide concentrations were determined at the same times. In control experiments the animals were subjected to the same manipulations except for being placed in the OF (the handling series). Instead of phenazepam they were given an injection of physiological saline (0.9% NaCI solution), and an OF test was carried out after the injection.