title: Role for the TRPV1 channel in insulin secretion from pancreatic beta cells.
abstract: Transient receptor potential channels have been put forward as regulators of insulin secretion. A role for the TRPV1 ion channel in insulin secretion has been suggested in pancreatic beta cell lines. We explored whether TRPV1 is functionally expressed in RINm5F and primary beta cells from neonate and adult rats. We examined if capsaicin could activate cationic non-selective currents. Our results show that TRPV1 channels are not functional in insulin-secreting cells, since capsaicin did not produce current activation, not even under culture conditions known to induce the expression of other ion channels in these cells. Although TRPV1 channels seem to be irrelevant for the physiology of isolated beta cells, they may play a role in glucose homeostasis acting through the nerve fibers that regulate islet function. At the physiological level, we observed that Trpv1 (-/-) mice presented lower fasting insulin levels than their wild-type littermates, however, we did not find differences between these experimental groups nor in the glucose tolerance test or in the insulin secretion. However, we did find that the Trpv1 (-/-) mice exhibited a higher insulin sensitivity compared to their wild-type counterparts. Our results demonstrate that TRPV1 does not contribute to glucose-induced insulin secretion in beta cells as was previously thought, but it is possible that it may control insulin sensitivity.
authors.affiliation: División de Neurociencias, Departamento de Neurodesarrollo y Fisiología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior S/N Avenida Universidad, Ciudad Universitaria, CP 04510, Coyoacán, Mexico DF, Mexico.
authors.forename: Carlos Manlio
authors.initials: CM
authors.lastname: Diaz-Garcia
authors.forename: Sara L
authors.initials: SL
authors.lastname: Morales-Lázaro
authors.forename: Carmen
authors.initials: C
authors.lastname: Sánchez-Soto
authors.forename: Myrian
authors.initials: M
authors.lastname: Velasco
authors.forename: Tamara
authors.initials: T
authors.lastname: Rosenbaum
authors.forename: Marcia
authors.initials: M
authors.lastname: Hiriart
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051379:Mice; D051381:Rats; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D007328:Insulin; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; C493922:Trpv1 protein, rat