title: Neurochemistry of neurons in the ventrolateral medulla activated by hypotension: Are the same neurons activated by glucoprivation?
abstract: Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed.
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.|ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, NSW, 2109, Australia.
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Parker
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Sheng
authors.initials: S
authors.lastname: Le
authors.affiliation: Department of Psychology, Faculty of Human Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Travis A
authors.initials: TA
authors.lastname: Wearne
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Hardwick
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.|Department of Pharmacology, School of Medical Science, University of New South Wales, NSW, 2052, Australia.
authors.forename: Natasha N
authors.initials: NN
authors.lastname: Kumar
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Robinson
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: McMullan
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
authors.forename: Ann K
authors.identifier: http://orcid.org/0000-0003-1544-7924
authors.initials: AK
authors.lastname: Goodchild
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism; D003847:Deoxyglucose / Q000494:pharmacology; D004745:Enkephalins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D050487:Glycine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D006830:Hydralazine / Q000494:pharmacology; D007022:Hypotension / Q000378:metabolism / Q000473:pathology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009448:Neurochemistry; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009478:Neuropeptide Y / Q000235:genetics / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015320:Tachykinins / Q000235:genetics / Q000378:metabolism; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: C495403:Adcyap1 protein, rat; D000959:Antihypertensive Agents; D002395:Catecholamines; D004745:Enkephalins; D050487:Glycine Plasma Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011498:Protein Precursors; D016760:Proto-Oncogene Proteins c-fos; C493269:Slc6a5 protein, rat; D015320:Tachykinins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; C044206:preprotachykinin; D006830:Hydralazine; C033660:preproenkephalin; D003847:Deoxyglucose
keywords: RRID: AB_141882; RRID: AB_2106783; RRID: AB_2157629; RRID: AB_2340606; RRID: AB_2535788; RRID: AB_477560; RRID: AB_514497; RRID: AB_518256; RRID: AB_627253; RRID: AB_90782; catecholamines; hypotension; neurochemical coding; ventrolateral medulla