Session: S56-Central Regulation and Actions of Prolactin
Room 301 (Moscone Center)
Neuroendocrine tuberoinfundibular dopamine (TIDA) neurons tonically inhibit pituitary prolactin release. Studies of these cells have focused on long-term control of transcription and dopamine synthesis. As a neuronal system, however, membrane properties and network interactions likely are just as important. Yet little has been known about TIDA electrophysiology. We have recently demonstrated that rat TIDA neurons discharge in a highly robust network oscillation that is synchronized via gap junctions. Prolactin itself provides feedback inhibition of its own release through stimulation of TIDA cells. We show that this feedback, in addition to increasing transcription and phosphorylation of tyrosine hydroxylase, involves depolarization coupled with broadening of action potentials. Combined, these mechanisms will boost dopamine release and, in turn, increase the brake on prolactin secretion. This work suggests that TIDA firing pattern may be a novel, important regulatory target in the lactotrophic axis.