[Effects of diazepam on rage reaction elicited by the lateral hypothalamus (LH) and on single unit activities in the LH and the basal medial amygdaloid nucleus (Abm) in cats (author's transl)].

Effects of diazepam were examined on the whine reaction elicited by LH stimulation and on unit activities in the LH and Abm in cats. The spontaneous firing frequency of Abm neurons was 5 to 30 spikes/sec and in all 6 neurons isolated the firing frequency increased by non-nociceptive and/or clap-stimulation. Diazepam decreased the spontaneous firing frequency of all Abm neurons isolated and the increased firing frequency elicited by non-nociceptive and/or clap-stimulation was also depressed by diazepam. The spontaneous firing frequency of neurons in the LH was 4 to 5 spikes/sec and all 6 neurons isolated firing frequency increased by non-nociceptive stimulation. Only one of 6 neurons, however, was activated by clap-stimulation. Diazepam decreased the spontaneous firing frequency of all LH neurons. Out of 6 neurons responsive to non-nociceptive stimulation, 3 were also depressed by diazepam. The other neurons were not affected by diazepam. These results suggest that depressed action of diazepam on the whine reaction elicited by the LH stimulation may be related to the decrease of firing in the Abm and/or the LH by diazepam.

[Effects of diazepam on evoked potential recorded from basal medial amygdaloid nucleus, lateral hypothalamus and midbrain reticular formation (author's transl)].

The evoked potential in the lateral hypothalamus (LH) recorded by stimulation of basal medial amygdaloid nucleus (Abm) showed a triphasic pattern and diazepam (2 mg/kg, i. p.) decreased the late component. The evoked potential in the midbrain reticular formation (MRF) recorded by stimulation of Abm showed a fast component with a relatively short latency followed by a biphasic late component and diazepam decreased the late component. Though the evoked potential in the Abm recorded by stimulation of LH showed a triphasic pattern, diazepam had no influence on the amplitude. Diazepam increased markedly the amplitude of evoked potential in the MRF recorded by stimulation of LH. Diazepam was ineffective on the evoked potential in the Abm recorded by stimulation of MRF. Diazepam decreased markedly the late component of evoked potential in the LH recorded by stimulation of MRF. These results suggest that the depression of emotional behavior by diazepam may be particularly related to the fact that the evoked potential in the LH recorded by stimulation of Abm was decreased by diazepam.

[Effects of MS4101, a new benzodiazepine compound, on evoked potentials induced by noxious stimulation of hind legs in cats].

The effects of 10-chloro-11b-(2'-fluorophenyl)-2,3,5,6,7,11b-hexahydro-7-(2''-hydroxyethyl)benzo[6,7]-1,4-diazepino [5,4-b]oxazol-6-one (MS4101), a new benzodiazepine compound, on evoked potential in cats were examined and compared with diazepam. Though evoked potential in somatic cortex I, motor cortex I and posterior groups induced by tibial nerve stimulation were unaffected by a small dose of MS4101 (1 mg/kg) which did not influence on limbic system, the amplitude of evoked potential in midbrain reticular formation was reduced. The amplitude of evoked potential in amygdala and hippocampus induced by cutaneous nerve stimulation was reduced by MS4101 and diazepam. These two drugs had the same effect on amygdala and difference in the degree of action between these drugs was not observed. Sham rage response following head shake, circling and whine behaviour was observed by electrical stimulation of the hypothalamus. The threshold of sham rage response by raised by MS4101 and diazepam.