Subdiaphragmatic vagus nerve activity and hepatic venous glucose are differentially regulated by the central actions of insulin in Wistar and SHR

Author(s)

Ribeiro, Izabela Martina R. ; Ferreira-Neto, Hildebrando C. ; Antunes, Vagner R.

• Document type: Journal article
• Source: PHYSIOLOGICAL REPORTS; v. 3, n. 5 MAY 2015.
• Web of Science Citations: 4

Abstract

Glucose is the most important energy substrate for the maintenance of tissues function. The liver plays an essential role in the control of glucose production, since it is able to synthesize, store, and release glucose into the circulation under different situations. Hormones like insulin and catecholamines influence hepatic glucose production (HGP), but little is known about the role of the central actions of physiological doses of insulin in modulating HGP via the autonomic nervous system in nonanesthetized rats especially in SHR where we see a high degree of insulin resistance and metabolic dysfunction. Wistar and SHR received ICV injection of insulin (100 nU/mu L) and hepatic venous glucose concentration (HVGC) was monitored for 30 min, as an indirect measure of HGP. At 10 min after insulin injection, HVGC decreased by 27% in Wistar rats, with a negligible change (3%) in SHR. Pretreatment with atropine totally blocked the reduction in HVGC, while pretreatment with propranolol and phentolamine induced a decrease of 8% in HVGC after ICV insulin injection in Wistar. Intracarotid infusion of insulin caused a significant increase in subdiaphragmatic vagus nerve (SVN) activity in Wistar (12 +/- 2%), with negligible effects on the lumbar splanchnic sympathetic nerve (LSSN) activity (-6 +/- 3%). No change was observed in SVN (-2 +/- 2%) and LSSN activities (2 +/- 3%) in SHR after ICA insulin infusion. Taken together, these results show, in nonanesthetized animals, the importance of the parasympathetic nervous system in controlling HVGC, and subdiaphragmatic nerve activity following central administration of insulin; a mechanism that is impaired in the SHR. (AU)

• FAPESP's process: 07/04085-0 - Functional analysis of genes contributing to neurogenic hypertension
• Grantee: Vagner Roberto Antunes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/13047-0 - Role of the autonomic nervous system in the hepatic production of glucose via central action of insulin in hypertensive animals
• Grantee: Izabela Martina Ramos Ribeiro de Toledo
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 10/05037-1 - Role of purinergic receptors of paraventricular nucleus of the hypothalamus in the neurogenic hypertension
• Grantee: Hildebrando Candido Ferreira Neto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/06206-0 - Gene expression changes of neuropeptides and proinflammatory factors of the hypothalamus and brainstem nucleus involved with cardiovascular regulation in diet-induced obesity animals
• Grantee: Vagner Roberto Antunes
• Support Opportunities: Regular Research Grants