[Norepinephrine regulation of T-lymphocyte proliferation of rat during acute hypoxia].

Interaction between the immune and neuroendocrine systems has long been noted. In the present study, the role of norepinephrine (NE) in immunoregulation of rats during simulated hypoxia in hypobaric chamber was examined. It was found that 7 km for 24 h of hypoxia inhibited T-lymphocyte proliferation by 41%. 7 d and 20 d of hypoxia, simulating 5 km altitude, reduces T-lymphocyte proliferation respectively 34% and 60%. Intracerebroventricular (i.c.v.) injection of 5 x 10(-6) mol/L NE decreased T-lymphocyte proliferation by 29%. I.c.v. injection of phentolamine 25 micrograms/rat prior to 7 km for 10 h hypoxia attenuated the hypoxia-induced suppression of T-lymphocyte proliferation from 42% to 21%. In additon, 7 km 10 h hypoxia increased CRF levels in blood and catecholamines in hypothalamus. An increased circulation CRF level was also noted after NE injection (i.c.v.) of 5 x 10(-6) mol/L. Hypoxia corresponding 7 km altitude for 10 h stimulates spleen-lymphocytes incubated with CRF, but T-lymphocyte proliferation decreclsed with increasing CRF concentration. These findings suggest that hypoxia inhibits T-lymphocyte proliferation probably through an immune inhibition action by CRF-NE.