Examination of some factors that control the effects of septal lesions on lordosis behavior

Abstract

Various experimental parameters related to the effects of septal lesions on the lordosis behavior of rats have been examined. First, the failure of septal lesions to facilitate lordosis behavior in male rats appears to be related to the degree of exposure to androgens neonatally. The normal facilitation in lordosis behavior associated with septal destruction in adult female rats does not occur if these female rats are treated with 1.0 mg of testosterone propionate (TP) on Day 1 of life. Yet female rats given 270 μg of TP on Day 3 of life respond the same as do normal females to septal lesions. Second, these sexually dimorphic effects of septal lesions can be modified in adult rats by chronic treatment with gonadal hormones following septal destruction. Whereas previous studies indicated that chronic estrogen injections permit a facilitation in lordosis behavior to occur in septal lesioned male rats, the present results showed that chronic injections of TP following a septal lesion attenuates the facilitation in lordosis behavior typically observed in adult female rats following a septal lesion. Third, examination of the time course for the facilitation in lordosis behavior following a septal lesion revealed a four to six day delay before the appearance of heightened female sexual behavior. Fourth, in support of the possibility that modifications in lordosis behavior by septal lesions may be mediated by a depletion or imbalance in brain amines, amphetamine was found to reduce the high levels of lordosis behavior of septal lesioned female rats to control levels. Finally, further evidence of a potential role for brain amines in the effects of septal lesions was provided by the observation of significantly lower content and turnover of dopamine in the amygdala of septal lesioned female rats, relative to sham operated controls.