Response of temperature-sensitive medullary neurons to acetylcholine, norepinephrine, and 5-hydroxytryptamine.
Single unit activity was recorded by means of five-barrel micropipettes from temperature-sensitive neurons in the reticular formation of the medulla oblongata in urethanized cats. Acetylcholine (ACh), norepinephrine (NE) and 5-hydroxytryptamine (5-HT) were applied microiontophoretically to the immediate vicinity of the neurons. Both thermally sensitive and insensitive units responded to ACh (82.0%) and 5-HT (93.0%) by increasing discharge rate. Iontophoretically applied atropine, but not hexamethonium, antagonized the excitatory responses to ACh. NE was shown to have different effects on the medullary neurons. Most temperature-insensitive units were either nonresponsive (52.4%) or excited (28.6%) by NE, while a majority of warm-sensitive (61.8%) and cold-sensitive (55.6%) neurons were inhibited by NE. Iontophoretically application of the alpha-adrenergic blocking agent, phentolamine, or the beta-antagonists, propranolol, or sotalol, produced no effect on the inhibitory responses to NE. These results tend to support the current concept of the transmitter role of monoamines in thermoregulation.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001833:Body Temperature Regulation / Q000187:drug effects*; D002415:Cats; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012154:Reticular Formation / Q000166:cytology / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology*; D013015:Sotalol / Q000494:pharmacology
D006584:Hexamethonium Compounds; D012701:Serotonin; D001285:Atropine; D011433:Propranolol; D013015:Sotalol; D000109:Acetylcholine; D009638:Norepinephrine; D010646:Phentolamine