Modulatory role of adrenergic nerves on dexamethasone-induced islet cell NPY expression in the rat: evidence from chemical sympathectomy.
We previously demonstrated induction of neuropeptide Y (NPY) in rat islet beta-cells by the glucocorticoid dexamethasone (DEX). Because noradrenergic nerves appear to regulate NPY expression in the central nervous system (CNS), we investigated whether DEX-induced islet cell expression of NPY could be modulated by catecholaminergic nerves. Therefore rats were treated with DEX (2 mg/kg, i.p., for 12 days) and received injections of 6-hydroxydopamine (6-OHDA; 80 mg/kg, i.v., at day 1 or 10). 6-OHDA treatment eliminated islet adrenergic nerves. The frequency of NPY-immunoreactive islet cells and the levels of islet cell NPY messenger RNA (mRNA) were markedly lower in rats given 6-OHDA at day 1 of the DEX-treatment period. In contrast, the frequency of NPY-immunoreactive cells and levels of islet cell NPY mRNA in DEX-treated rats receiving 6-OHDA at day 10 did not differ from those treated with DEX alone. The findings suggest that DEX-induced islet cell expression of NPY is partially dependent on adrenergic nerves and that the effect of sympathectomy is exerted at an early stage of the NPY induction.
Myrsén-Axcrona
U
U
Department of Physiology and Neuroscience, Lund University Hospital, Sweden.
Ahrén
B
B
Sundler
F
F
D018663:Adrenergic Agents / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D008297:Male; D009478:Neuropeptide Y / Q000096:biosynthesis*; D016627:Oxidopamine / Q000494:pharmacology; D051381:Rats; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D013565:Sympatholytics / Q000494:pharmacology
D018663:Adrenergic Agents; D007328:Insulin; D009478:Neuropeptide Y; D013565:Sympatholytics; D003907:Dexamethasone; D016627:Oxidopamine