CENTRAL ADMINISTRATION OF 8-OH-DPAT AND MCPP STIMULATES PROLACTIN SECRETION IN OVARIECTOMIZED, ESTROGEN-TREATED RATS - LACK OF AN EFFECT ONTUBEROINFUNDIBULAR DOPAMINERGIC NEURON ACTIVITY

The effects of central administration of two serotonin receptor agonis ts, 8-OH-DPAT and mCPP, on tuberoinfundibular dopaminergic (TIDA) neur on activity and serum prolactin (PRL) levels in ovariectomized, estrog en-treated rats were determined. 8-OH-DPAT dose-dependently (0.1-10 mu g/rat, icv) stimulated serum PRL levels, and depressed serotonergic n euron activity in 30 min. However, the TIDA neuron activity was not af fected at all. Similar treatment of mCPP was less effective than 8-OH- DPAT: only the highest dose of mCPP (10 mu g) stimulated PRL secretion and inhibited serotonergic neuron activity. No change in TIDA neuron activity was observed either. We conclude that central serotonin acts on 5-HT1 receptors to stimulate the PRL secretion, which may not invol ve the TIDA neurons.