Plasma Concentrations of Hypophyseal Hormones and Corticosterone in Male Mice Acutely Exposed to Simulated High Altitude 1 2

Abstract

Summary

The concentrations of gonadotropins, growth hormone, prolactin, and corticosterone were determined in plasma pools (n = 12) obtained from male mice immediately after a 4-hr exposure to 632, 523, 429, 349, or 282 Torr (simulating 5000-25,000 ft altitude). The mice in all groups were deprived of food and water during the 4-hr treatment period. The peripheral levels of LH were consistently reduced (P < 0.05) by exposure to an altitude as low as 5000 ft, whereas plasma FSH and GH estimates were somewhat reduced at simulated high altitude as compared to sea level controls. Plasma PRL concentration was not uniformly affected by simulated altitude exposure, but circulating corticosterone values increased (P < 0.05) at altitudes above 15,000 ft. The findings of this study demonstrate that moderate hypoxia, per se, can significantly reduce the plasma concentrations of LH, and to a lesser degree FSH and GH, even in the absence of changes in dietary intake, systemic hypothermia, and the stress-related rise in plasma corticosterone.