Effects of serotonin on the electric activity of paraventricular neurons of in vitro rat hypothalamic slices

Hypothalamic slices were prepared with a vibratome.The spontaneousdischarge of 46 paraventricular neurons was recorded by glass microelectrodefrom 20 such slices,and effects of seromnin on spontaneous discharge were observ-cd.After perfusing the brain slices with artificial cerebro-spinal fluid contain-ing serotonin(10~(-6)mol/L)for 3 min,discharge rate of 16 units is significantlyincreased with latency 1.21±1.21(mean+SD)min,this response is blocked byserotonin antagonist,cyproheptadine.The discharges of 3 units were decreased,but 25 units non-responsive.The experimental results suggest that about 1/3of paraventricular neurons can be activated by topical application of serotoninvia the activation of 5-HT receptors.