title: Single-unit activity of hypothalamic arcuate neurons in brain tissue slices. Effects of anterior pituitary hormones, cholecystokinin-octapeptide, and neurotransmitters.
abstract: Extracellular single-unit activity was recorded from hypothalamic arcuate nucleus (ARC) in brain tissue slices. Adult female Sprague-Dawley rats, ovariectomized or ovariectomized plus estrogen treated for at least 1 week, were used. Resting activity and responses of ARC neurons to six anterior pituitary hormones, or (as a positive control) cholecystokinin-octapeptide sulfate (CCK-8S), and a battery of four neurotransmitters including norepinephrine, serotonin, dopamine, and glutamate were recorded. A total of 263 neurons were recorded. Estrogen treatment did not cause any significant changes in the firing patterns nor in responses to most agents tested except for CCK-8S. A large percentage of the ARC neurons were either silent (40%) or slow-firing units (43% fired less than twice/s). Only a small percentage of ARC neurons (20-30%) responded to the anterior pituitary hormones, and these responses were small, delayed increases in firing despite the fact that CCK-8S stimulated more than half of the neurons with large responses. Glutamate was also excitatory, but not quite as effective as CCK-8S. Norepinephrine and serotonin were equally effective in eliciting a neuronal response (over 70% of units responded with an excitation or inhibition). Dopamine acted like norepinephrine, but was less potent. Since anterior pituitary hormones only weakly affected ARC neurons, these electrophysiological data give scant support to the notion that short-loop feedback is accompanied by electrical changes. In the ARC, however, CCK-8S may play some functional roles that are influenced by estrogen.
authors.forename: J T
authors.initials: JT
authors.lastname: Pan
authors.forename: L M
authors.initials: LM
authors.lastname: Kow
authors.forename: D W
authors.initials: DW
authors.lastname: Pfaff
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005973:Glutamine / Q000494:pharmacology; D013006:Growth Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000494:pharmacology; D009474:Neurons / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D010908:Pituitary Hormones, Anterior / Q000494:pharmacology*; D011388:Prolactin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology*; D013972:Thyrotropin / Q000494:pharmacology
chemical_list: D018377:Neurotransmitter Agents; D010908:Pituitary Hormones, Anterior; D005973:Glutamine; D012701:Serotonin; D004958:Estradiol; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone; D012844:Sincalide; D009638:Norepinephrine