Hypoxia influences enkephalin release in rats.
To investigate hypoxia effects on leucine-enkephalin (L-ENK) levels of median eminence (ME) of hypothalamus in rats, and the possible glucocorticoid involvement in modulation. Hypoxia was stimulated in a hypobaric chamber. L-ENK levels were measured by specific radioimmunoassay during acute, and a comparison of L-ENK alteration was taken for bilateral adrenalectomy (ADX) with or without a replacement of dexamethasone (DEX). Acute hypoxia 10.8% O2 for 30 min and 2 h markedly enhanced L-ENK levels of ME from 23.99+/-7.25 in control to 51.26+/-16.96 (P<0.01) and 53.29+/-26.10 ng/mg protein (p<0.01), and acute hypoxia at 8.2% O2 significantly increased L-ENK of ME to 36.76+/-15.25 (p<0.05) and 32.09+/-3.58 ng/mg protein (p<0.05). The increased L-ENK was returned to normoxic level when hypoxia (10.8% O2) exposure lasted for 24 h. After ADX, 10.8% O2 hypoxia induced a sharp decline of L-ENK in the ME, but this decline was completely reversed by treatment with DEX (500 microg/rat, i.p.). Acute hypoxia increases L-ENK level of hypothalamic ME in rats, which may present a reduced and/or inhibited release of L-ENK, acting through a fast negative feedback mechanism of acute hypoxia activated high circulating glucocorticoid level.
Chen
X Q
XQ
Division of Neurobiology and Physiology, College of Life Sciences, Zhejiang University, Hangzhou, PR China.
Du
J Z
JZ
D000208:Acute Disease; D000315:Adrenalectomy; D000818:Animals; D001274:Atmospheric Pressure; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D003907:Dexamethasone / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology; D002534:Hypoxia, Brain / Q000378:metabolism*; D008297:Male; D008473:Median Eminence / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000378:metabolism
D005938:Glucocorticoids; D004743:Enkephalin, Leucine; D003907:Dexamethasone