Temperature dependence of in vitro androgen production in testes from hibernating ground squirrels, Spermophilus lateralis

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Abstract
The effect of temperature on the in vitro androgen secretion of testes from hibernating ground squirrels was measured in response to stimulation by luteinizing hormone (LH). We wished to determine whether hibernating ground squirrels can maintain responsiveness of gonads while at the low body temperatures of torpor. In gonads incubated at 32 °C, secretion of testosterone increased in a dose-dependent manner in response to ovine-LH or ground squirrel pituitary homogenate. This responsiveness was reduced at 20 and 9 °C and absent at 5 °C, the temperature that most closely approximates the body temperature of torpid ground squirrels. This temperature sensitivity was similar to that in the nonhibernating laboratory mouse. Superfusion of ground squirrel testes revealed a lag of testosterone secretion in response to LH and, additionally, an ability of testes to secrete testosterone after being only briefly exposed to ovine-LH while at 5 °C. These results provide evidence against a hypothesis of temperature compensation that would allow continued testis function during torpor, and support a previous study which indicated that gonadal growth is restricted to intervals of normothermy during and after the hibernation season.

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