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

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.