[Effects of noradrenaline and acetylcholine on electric activity of paraventricular neurons of rat hypothalamic slices].

The effects of noradrenaline (NA) and acetylcholine (ACh) on 90 paraventricular neurons from 31 hypothalamic slices prepared from rat were observed. After perfusing the brain slices with NA (10(-6) mol/L, 3 min), discharge rate of 14/73 (17%) nonphasic and 7/12 (58.3%) phasic neurons was significantly increased, while that of 10/73 (12%) nonphasic and 2/12 (16.6%) phasic neurons was significantly decreased, even ceased. 50/73 (64%) of the nonphasic and 3/12 (25%) of the phasic neurons were non-responsive. The effects of NA on the nonphasic neurons were completely blocked by alpha receptor blocker phentolamine. The effects of NA on phasic neurons were partly blocked by phentolamine or propranolol (beta receptor blocker). After perfusing hypothalamic slices with ACh (10(-7) mol/L, 3 min), the firing rate of 15/73 (19%) nonphasic and 6/12 (50%) phasic neurons was increased, while that of 9/73 (11%) nonphasic and 2/12 (16.6%) phasic neurons was decreased. 54/73 (69%) nonphasic and 4/12 (33.3%) phasic neurons were non-responsive. The effect of ACh on the neurons could be reversed by atropine. The effect of scopolamine (M blocker) is similar to that of atropine. The experimental results suggest that the excitatory or inhibitory effect of NA or ACh on paraventricular neurons has mediated respectively by alpha, beta or M receptors.