Four-week ethanol drinking increases both thyrotropin-releasing hormone (TRH) release and content in rat pancreatic islets

Ethanol and urea affect insulin secretion from islets and insulinoma cells by different mechanisms

“…Stimulating effect of ethanol on insulin secretion from INS-1 and 1E cells is in accordance with previous data showing the ethanol-induced release of TRH and insulin from freshly isolated islets of Langerhans (Benicky et al 1997(Benicky et al , 2000. Ethanol added in vitro stimulated secretion in various systems including taurine and aspartate release from primary astrocytes (Kimelberg et al 1993) and secretion of peptide and protein hormones, e.g.…”

“…In natural islet cells ethanol induced insulin secretion only in isosmotic but not in hyperosmotic solution when swelling was absent (Benicky et al 2000). In the present study, ethanol in hyperosmotic medium failed to stimulate and even inhibited insulin release from clonal cells, thus indicating that osmotic component plays a role in its stimulation.…”

“…Cell swelling induced by small permeant molecules (ethanol or urea) results in a secretory response in various types of cells (Sato et al 1990a,b;Inukai et al 1992Inukai et al , 1993Benicky et al 1997Benicky et al , 2000Kucerova & Strbak 2001), but mechanism of its effect inducing exocytosis is relatively unrecognized (Strbak & Greer 2000). Ethanol and urea are osmotically active substances that easily cross the plasma membrane.…”

“…Secretion of essentially all so-packaged hormones, including pituitary luteinizing hormone, follicle-stimulating hormone, adrenocorticotropic hormone, melanocyte-stimulating hormone, thyroid-stimulating hormone, prolactin (Greer et al 1983(Greer et al , 1985(Greer et al , 1990Wang et al 1989;Sato et al 1990aSato et al , 1991, β-endorphin (Back et al 2000), hypothalamic gonadotropin-releasing hormone (Inukai et al 1992), pancreatic insulin (Blackard et al 1975), and glucagon (Blackard et al 1975), is stimulated by cell swelling. Swelling-induced thyrotropin-releasing hormone (TRH) secretion from pancreatic islets (Benicky et al 1997(Benicky et al , 2000, hypothalamic structures (Kucerova & Strbak 2001;Najvirtova et al, 2003;Bacova et al 2006b) and heart (Bacova et al 2006a) was demonstrated. Nevertheless, cell swelling-induced exocytosis possesses lim-1040 R. Hafko et al ited selectivity; cells specifically engaged in water and salt regulation retain their specific response to osmotic stimuli (Najvirtova et al 2003;Bacova et al 2006a,b).…”

“…Although first report appeared a long time ago (Blackard et al 1975), only recently this phenomenon has attracted appropriate attention (Benicky et al 2000;Straub & Sharp 2002;Bacova et al 2005Bacova et al , 2007Orecna et al 2008). Comparison with signal transduction mediating glucose-induced insulin secretion indicates the presence of a novel signaling pathway (Bacova et al 2005).…”