Preoptic unit responses to microelectrophoresis of neurotensin and its antiserum in female rats

Abstract We and other investigators have demonstrated the stimulation of luteinizing hormone secretion following the microinjection of neurotensin (NT) into the medial preoptic area in female rats. The present study electrophysiologically examined the action of the peptide in the same brain region. Microelectrophoresis of NT produced either excitation or inhibition in 24% of the medial preoptic neurons tested in oestrogen-primed and unprimed ovariectomized animals. Effective blockade of NT-induced excitatory and inhibitor unit responses by means of the simultaneous application of an antiserum to NT (anti-NT) indicated that they were produced by specific actions of the peptide. In addition, anti-NT by itself altered the spontaneous firing rate in some NT-responsive cells. These findings are in accord with the hypothesis that the preoptic area is a site of the action of NT in the female rat.