Manipulation of androgens causes different energetic responses to cold in 60- and 40-day-old male rats.

Previous studies suggested that adults respond differently than pubertal male rats to cold stress. To test the role of androgens in this difference, we adrenalectomized and replaced with corticosterone either 60- or 40-day-old male rats, then sham gonadectomized (Intact), gonadectomized (GDX), or GDX and replaced with testosterone (T; GDX+T) or dihydrotestosterone (DHT). One-half remained at room temperature (RT), and one-half lived in cold for 5 days. Cold reduced T in adult but not in pubertal Intacts. In 60-day-old rats, GDX with or without T replacement had minor effects on body weight (BW) and food intake (FI) at RT and cold. In 40-day-old rats at RT, androgens had slight effects; however, androgens affected almost all variables in cold. Separation of 40-day-old T-treated rats into two groups (moderate T levels, 1.4 ng/ml; high T levels, 1.9 ng/ml) revealed major differences between the groups. Moderate T (and DHT) prevented cold-induced loss of BW and increased FI. No T and high T induced decreased BW and FI in cold. We conclude that at 40 days of age, partial resistance to stress-induced reduction of T and high sensitivity to small changes in T have markedly positive effects on threatened energy balance.