LONG-TERM EFFECTS OF ANDROGEN TREATMENT ON FEAR REACTIONS IN EWES

We have previously demonstrated that testosterone treatment reduces fe ar reactions of ewes subjected to daily injections of testosterone pro pionate (10 mg/day) for 56 days, The long-term effects of this treatme nt were studied in the same ewes and using the same battery of fear-el iciting tests (isolation from conspecifics, surprise, and presence of a human) 4 and 8 months after the injections were terminated. Twenty-s ix behavioral items related to fear were recorded. A number of differe nces in the behavior of treated vs control animals indicate that the f ormer are still less fearful, especially in the surprise and human tes ts. Overall fearfulness scores of treated and control ewes (the higher the score, the more fearful the animals) were 7.3 +/- 1.7 vs 9.7 +/- 1.9, (P < 0.05) for the surprise test, and 7.0 +/- 1.4 vs 10.0 +/- 2.0 (P < 0.01) for the human test at 4 months, and 6.8 +/- 1.4 vs 8.2 +/- 1.1 (P < 0.05) for the human test at 8 months. Thus, not only does te stosterone treatment reduce fear reactions in ewes but it also has a l ong lasting effect on such reactions. (C) 1996 Academic Press, Inc.