Daily and Seasonal Variation in Adrenal Metabolism of the Brown Lemming

Publisher Website
Google Scholar
Abstract
Ad-renal metabolic variations were estimated by determining respiratory and secretory rates of cultured glands obtained from the brown lemming (Lemmus trimicronatus) collected in the Point Barrow, Alaska vicinity during the arctic summer and the arctic winter. Daily and seasonal variations in respiratory activity were apparent from measurements taken during three expeditions. Secretory activities displayed by the cultured glands reflect daily patterns of 24-hr, rhythmicity. Secretory activities of glands obtained from lemmings in the precipitous decline phase of a population cycle were conspicuously higher than the steroid synthesis and release rates evidencedby adrenals obtained prior to, and following this crisis. The additional observation that crisis glands were less responsive to exogenous ACTH than were non-crisis glands constitutes a further basis for metabolic distinction of population crises. The data are discussed in terms of population control hypotheses based on physiological adaptations.