Seasonal changes in plasma and adrenal concentrations of cortisol,corticosterone, aldosterone,and electrolytes in the adult male sand rat (Psammomys obesus)

Seasonal changes in adrenocortical function were studied in the adult male sand rat (Psammomys obesus) live-trapped in the region of Béni-Abbès in the Algerian Sahara Desert. Cortisol was found to be the primary corticosteroid secreted in the sand rat. Plasma and adrenal concentrations of cortisol, corticosterone, and aldosterone exhibited marked significant annual variations mainly characterized by a decline during spring, a minimum in early summer, and an increase in autumn. In spite of the high sodium intake of this animal in the field, the aldosterone levels seemed similar to those of other mammals. Plasma sodium and potassium concentrations were relatively high in Psammomys obesus (respectively, about 150 and 8 mM) and, except for a slight increase in early summer, varied little throughout the year.