Modulatory actions of luteinizing hormone-releasing hormone on electrical activity of preoptic neurons in brain slices.
Single unit activity was recorded from 378 neurons, in two preoptic nuclei rich in luteinizing hormone-releasing hormone neurons, using in vitro brain tissue slices which were prepared form either ovariectomized or ovariectomized plus estradiol-treated rats. To test possible transmitter-like actions, agents were injected into the perfusion medium. Luteinizing hormone-releasing hormone excited 46%, inhibited 7%, and evoked biphasic responses in 2% of the 250 units tested. By comparison, two other peptides, thyrotropin-releasing hormone and cholecystokinin-octapeptide sulfated were exclusively excitatory, acting on 55 and 67% of the neurons, respectively. The response to thyrotropin-releasing hormone, cholecystokinin-octapeptide sulfated, and neurotransmitters were prompt, large, and consistent from trial to trial. In contrast, responses to luteinizing hormone-releasing hormone were usually delayed, small, and variable. Responses to the agents tested were not affected by in vivo estradiol treatment. Possible modulatory actions of luteinizing hormone-releasing hormone were tested by comparing the responses of single neurons to norepinephrine and serotonin before and after an application of luteinizing hormone-releasing hormone. In 39 and 20% of the 119 neurons tested, the norepinephrine responses were potentiated and attenuated, respectively, by luteinizing hormone-releasing hormone. In 46 serotonin-responsive neurons, 28% were potentiated and 22% attenuated. These neuromodulatory actions of luteinizing hormone-releasing hormone were specific in affecting only certain responses of certain neurons, and they were not duplicated on the same neurons by thyrotropin-releasing hormone. It appears that luteinizing hormone-releasing hormone may be a neuromodulator in the preoptic area.
Pan
J T
JT
Rockefeller University, New York, NY 10021.
Kow
L M
LM
Pfaff
D W
DW
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D012701:Serotonin; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D013973:Thyrotropin-Releasing Hormone; D012844:Sincalide; D009638:Norepinephrine