Male and female Fitch ferrets, aged 12-19 wk, were purchased from Marshall Farms (North Rose, NY) and were housed individually in modified rabbit cages (24’’ X 12’’ X 18’’) on a long-day (16L:8D) photoperiod. All ferrets were fed a diet of moistened Purina ferret chow and were given water ad libitum. Ferrets were gonadectomized under ketamine (95 mg/kg) and xylazine (12 mg/kg) anesthesia. All ferrets received daily s.c. injections of TP (5 mg/kg) dissolved in sesame oil. When administered to castrated male ferrets, this dose of TP elicits the full range of masculine sexual behaviors and sustains plasma levels of testosterone that are characteristic of gonadally intact male ferrets in breeding condition.
We selected testosterone, instead of estradiol, as the activational sex steroid used in these experiments because a previous study showed that TP treatment successfully augmented neuronal Fos responses to estrous odors in both male and female rats after gonadectomy. It is possible that estradiol treatment would have exerted a similar effect in rats and would have duplicated the facilitatory effects of TP on pheromone-in-duced neuronal Fos responses seen in the present study using ferrets.