Horm Metab Res 2005; 37(8): 482-488
DOI: 10.1055/s-2005-870323
Original Basic
© Georg Thieme Verlag KG Stuttgart · New York

Hyperglycemia Induced by Pharmacological Activation of Central Serotonergic Pathways Depends on the Functional Integrity of Brain CRH System and 5-HT3 Receptors

F.  Carvalho1 , D.  Barros1 , J.  Silva1 , E.  Rezende1 , M.  Soares2 , J.  Fregoneze2 , E.  de Castro-e-Silva2
  • 1 Life Sciences Department, Bahia State University, 41195-001 Salvador, Bahia, Brazil
  • 2 Department of Physiology, Health Sciences Institute, Federal University of Bahia, 40110-100 Salvador, Bahia, Brazil
Further Information

Publication History

Received 20 November 2003

Accepted after revision 8 November 2004

Publication Date:
01 September 2005 (online)

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Abstract

In the present study, we investigated the effect of central serotonergic pathway activation achieved through third ventricle injections of quipazine, a serotonergic agonist, on plasma glucose levels of fasted and fed adult Wistar male rats, whose third ventricles were canulated 7 days before the experiments. Central quipazine administration induced a significant increase in plasma glucose levels in fasted animals, but was unable to modify plasma glucose concentrations in fed rats. Pretreatment with α-helical CRH, a CRH antagonist, significantly attenuated quipazine-induced hyperglycemia. Pretreatment with two different 5-HT3 receptor antagonists, LY-278,584 and ondansetron, was also able to produce a significant reduction in the hyperglycemic response evoked by central administration of quipazine. None of the antagonists used was capable of modifying plasma glucose concentrations when injected alone into the third ventricle. Quipazine-treated, hyperglycemic animals did not show any increase in plasma insulin levels. We conclude that acute pharmacological serotonergic stimulation by quipazine produces hyperglycemia by mechanisms that require the functional integrity of both CRH and 5-HT3 receptors, and that impairment in insulin secretion and/or activity may explain hyperglycemia induced by third ventricle injections of quipazine.

References

Emilio de Castro e Silva M. D., Ph. D.

Universidade Federal da Bahia, Instituto de Ciências da Saúde , Departamento de Fisiologia

40110-100 Salvador · BA, Brazil

Phone: +55 71 32357518

Fax: +55 71 3263 7067 ·

Email: emilio@ufba.br