title: Different adrenal sympathetic preganglionic neurons regulate epinephrine and norepinephrine secretion.
abstract: Brain stimulation or activation of certain reflexes can result in differential activation of the two populations of adrenal medullary chromaffin cells: those secreting either epinephrine or norepinephrine, suggesting that they are controlled by different central sympathetic networks. In urethan-chloralose-anesthetized rats, we found that antidromically identified adrenal sympathetic preganglionic neurons (SPNs) were excited by stimulation of the rostral ventrolateral medulla (RVLM) with either a short (mean: 29 ms) or a long (mean: 129 ms) latency. The latter group of adrenal SPNs were remarkably insensitive to baroreceptor reflex activation but strongly activated by the glucopenic agent 2-deoxyglucose (2-DG), indicating their role in regulation of adrenal epinephrine release. In contrast, adrenal SPNs activated by RVLM stimulation at a short latency were completely inhibited by increases in arterial pressure or stimulation of the aortic depressor nerve, were unaffected by 2-DG administration, and are presumed to govern the discharge of adrenal norepinephrine-secreting chromaffin cells. These findings of a functionally distinct preganglionic innervation of epinephrine- and norepinephrine-releasing adrenal chromaffin cells provide a foundation for identifying the different sympathetic networks underlying the differential regulation of epinephrine and norepinephrine secretion from the adrenal medulla in response to physiological challenges and experimental stimuli.
authors.affiliation: Department of Physiology, Northwestern University Medical School, Chicago, Illinois 60611, USA. s-morrison2@northwestern.edu
authors.forename: S F
authors.initials: SF
authors.lastname: Morrison
authors.forename: W H
authors.initials: WH
authors.lastname: Cao
mesh_terms: D000200:Action Potentials; D000313:Adrenal Medulla / Q000294:innervation* / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002838:Chromaffin System / Q000294:innervation / Q000378:metabolism; D003847:Deoxyglucose / Q000494:pharmacology; D004558:Electric Stimulation; D004837:Epinephrine / Q000378:metabolism*; D005071:Evoked Potentials; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism*; D011311:Pressoreceptors / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D003847:Deoxyglucose; D009638:Norepinephrine; D004837:Epinephrine