Three to four weeks after intracerebral infusion, experimental females were
given estradiol benzoate (18g/kg) about 52 h before the tests were begun. Progesterone
(1 mg/rat) was injected 48 h after estradiol and 4 h before the beginning of
tests. Both steroids were purchased from Sigma, St. Louis, MO, dissolved in peanut
oil and injected sc in 1ml/kg and .2 ml/rat, respectively. These doses are known to
produce a lordosis quotient close to 100 [2,69]. An equal number of experimental
and control females were used simultaneously in each test. The VMN and MePDA
groups were tested on different days.