The Medial Hypothalamus and Prehibernation Obesity: A Theory Based on Behavioral Tests
In the late summer and autumn many hibernating species become fat, sometimes grossly so (Plate 5); common experience, field studies, and measurements in the laboratory all agree on this. According to Manville (1959) some Columbian ground squirrels, “during the last few weeks before hibernating, appear to nearly double their weight and become so fat they can scarcely waddle, their bellies literally drooping to the ground as they stand erect.” Fat indices for bats, Eptesicus fuscus, caught in the wild increase sharply in the late summer (Weber and Findley, 1970). In arctic ground squirrels fed on Purina Lab Chow there are periods of augmented food intake that correspond to the period of prehibernation fat accumulation (Sept. 4 to Oct. 24) in natural populations (Mayer, 1954).1 In golden-mantled ground squirrels caught in the wild, there is a three-fold increase in the lipid index during the month of August (Jameson and Mead, 1964; and see Fig. 3).
KeywordsGround Squirrel Median Eminence Arcuate Nucleus Lesion Animal Hypothalamic Lesion
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