Studies on the Adrenal and Thyroid Glands of the Ground Squirrel During Hibernation

Abstract

SUMMARY Hibernation in the ground squirrel ends within 1–2 hr after total adrenalectomy and does not recur. Survival time after adrenalectomy in laboratory-kept ground squirrels during November and December was longer than it was during September-October and February-March. Body temperature during hibernation (4–18° C) was restored to normal (37° C) within 1–2 hr after adrenalectomy, the animals being kept in a room at 17° C. Oxygen consumption was measured in ground squirrels on the 6th and 7th days after adrenalectomy at 31–32° and 4° C respectively. Maximum consumption occurred at 4° C; normal body temperature was retained. The 131I uptake by the thyroid of non-hibernating ground squirrels is considerably smaller in early Autumn (September-October) than during the winter months. Radioactive iodine is not accumulated by the thyroid gland of the hibernating ground squirrel, but 3 days after adrenalectomy the amount of 131I accumulated is equivalent to that taken up by the gland of the non-hibernating animal. The effects of adrenalectomy in the hibernating and non-hibernating ground squirrel are compared with those obtained in hypothermic rats maintained in similar environmental conditions.

The Pineal Complex and Thermoregulation

“…In many mammalian species adrenalectomy or thyroidectomy causes death upon exposure to a cold environment, while administration of thyroxine, or cortisone and thyroxine, increases the ability to maintain body temperature during such exposure (Sellers & Flattery, 1973). The adrenals also appear to be important in the initiation of and arousal from hibernation (Vidovic & Popovic, 1954;Kayser, 1957). Although there is little evidence that thyroid activity is associated with hibernation, this gland appears to be important in the development of cold acclimation (Sellers & You, 1950).…”

Contribution À La Connaissance Du Cycle Annuel De La Chauve-Souris Rhinolophus Ferrumequinum (Schreber, 1774)

“…La plupart des auteurs (Adler, 1920 ;Coninx-Girardet, .1927et Lachiver, 1952Kayser et Aron, 1938et 1952 Cricetas cricetus et Citellus citellus ; Zalesky et Wells, 1940et Hoffman et Zarrow, 1958Smit-Vis, 1962et Suomalalainen, 1964, chez Erinaceus europaeus) admettent que la glande est au repos en automne et pendant l'hibernation, ou tout au moins la premiere partie de celle-ci. Skowron et Zajaczek (1947) chez le Herisson, Vidovic et Popovic (1954) chez des Spermophiles, Lachiver (J952a), Lachiver et al (1957), Gabe et al (1963) chez Eliomys quercinns, constatent en outre une augmentation progressive de ractivite (ou tout au moins de Pactivite potentielle) de la thyroide a partir des mois de decembre ou Janvier, culminant au moment du reveil vernal.…”

Activité Thyroidienne De Microcebus Murinus (Miller, 1777). Influence De La Captivité

“…Beaucoup d'especes hibernantes (Hamster, Spermophile, Lerot, Orvet, Rhinolophe, H^risson) presentent, pour la plupart d'entre elles, un repos hivernal de la thyroide suivie d'une activation au moment du reveil printanier ou le precedant (Kayser 1952(Kayser , 1965Vidovic 1954;Hoffmann 1958;Lachiver 1957Lachiver , 1959Gabe 1964;Saint Girons 1963Pinatel 1970). Le Microcebe präsente un cycle similaire d'activite thyroidienne : au repos de septembre ä Janvier, la thyroide est active de fevrier ä aoüt pendant la Saison de reproduction.…”