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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Injections of the alpha-2 adrenoceptor agonist clonidine into the dorsal raphe nucleus increases food intake in satiated rats

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Flores, Rafael Appel [1] ; Steinbach, Renata [1] ; Pedroso, Joao A. B. [2] ; Metzger, Martin [2] ; Donato, Jr., Jose [2] ; Paschoalini, Marta Aparecida [1]
Total Authors: 6
[1] Fed Univ Santa Catarina UFSC, Ctr Biol Sci CCB, Dept Physiol Sci, BR-88040970 Florianopolis, SC - Brazil
[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Neuropharmacology; v. 182, JAN 2021.
Web of Science Citations: 0

The present study aimed to evaluate the effects of pharmacological manipulation of alpha-adrenergic agonists in the dorsal raphe nucleus (DR) on food intake in satiated rats. Adult male Wistar rats with chronically implanted cannula in the DR were injected with adrenaline (AD) or noradrenaline (NA) (both at doses of 6, 20 and 60 nmol), or alpha-1 adrenergic agonist phenylephrine (PHE) or alpha-2 adrenergic agonist clonidine (CLO) (both at doses of 6 and 20 nmol). The injections were followed by the evaluation of ingestive behaviors. Food and water intake were evaluated for 60 min. Administration of AD and NA at 60 nmol and CLO at 20 nmol increased food intake and decreased latency to start consumption in satiated rats. The ingestive behavior was not significantly affected by PHE treatment in the DR. CLO treatment increased Fos expression in the arcuate nucleus (ARC) and paraventricular nucleus of the hypothalamus (PVN) in rats that were allowed to eat during the experimental recording (AF group). However, when food was not offered during the experiment (WAF group), PVN neurons were not activated, whereas, neuronal activity remained high in the ARC when compared to control group. Noteworthy, ARC POMC neurons expressed Fos in the AF group. However, double-labeled POMC/Fos cells were absent in the ARC of the WAF group, although an increase in Fos expression was observed in non-POMC cells after CLO injections in the WAF group. In conclusion, the data from the present study highlight that the pharmacological activation of DR alpha-adrenoceptors affects food intake in satiated rats. The feeding response evoked by CLO injections into DR was similar to that induced by NA or AD injections, suggesting that the hyperphagia after NA or AD treatment depends on alpha-2 adrenoceptors activation. Finally, we have demonstrated that CLO injections into DR impact neuronal activity in the ARC, possibly evoking a homeostatic response toward food intake. (AU)

FAPESP's process: 17/16473-6 - Processing of aversive stimuli: circuitry between the laterodorsal tegmental nucleus, the habenula, and dorsal and median raphe nuclei
Grantee:Martin Andreas Metzger
Support type: Regular Research Grants
FAPESP's process: 17/02983-2 - The role of growth hormone in the brain: relevance for neural functions and in disease
Grantee:Jose Donato Junior
Support type: Research Projects - Thematic Grants
FAPESP's process: 12/15517-6 - Involvment of molecular factors in metabolic changes during pregnancy: role of SOCS3
Grantee:Thais Tessari Zampieri
Support type: Scholarships in Brazil - Doctorate