Dopaminergic modulation of reproductive behavior and activity in male zebra finches

Abstract

We previously demonstrated that hormone treatments which stimulate female-directed singing increased levels and turnover of dopamine (DA) in brain areas controlling the motor patterning of song. To help determine how DA affects singing, we quantified the effects of treating adult male finches with the D1/D2 receptor antagonist cis-flupenthixol. Adult males were given subcutaneous silastic implants of androgen, in case drug treatment interfered with androgen secretion. One week later, they were tested with females. Males were divided into three groups matched for levels of courtship singing. Males were then subcutaneously implanted with osmotic minipumps containing either saline, a low, or a high dose of cis-flupenthixol. Each male was tested with a different female 5 and 10 days after implantation to determine how this D1/D2 receptor antagonist affected behavior. Both drug doses affected female-directed singing 5 days after initiation of treatment. High-dose males sang to females significantly less often than males in the other two groups. Low-dose males showed fewer high-intensity courtship displays in which males dance towards females as they sing. These effects on courtship singing were not seen at day 10, though other behavioral effects were seen at this time. Male beak wipes, rocks, following females and female withdrawals from males were also affected by drug treatment. General activity in the home cage was decreased by day 11. These data demonstrate that singing and several other female-directed behaviors are sensitive to perturbations in DA receptor function.

Fig. 1

The effects of 0, 5 or 10 days treatment with vehicle (VEH), 0.5 (LOW) or 5 μg/g/day (HIGH) of the mixed D₁/D₂ receptor antagonist, cis-flupenthixol (N = 9, 13, 10 respectively) on mean courtship singing and copulatorybehavior (± SEM) in zebra finches. While these graphs present mean behavioral frequencies (± SEM) for each test, the analyses were run on difference scores, subtracting each bird’s score on its initial pre-drug test from its scores on each drug test (See Data Analysis). ^HSignificantly different from high-dose males, P < 0.05. ^HHSignificantly different from high-dose males, P < 0.01. ^VSignificantly different from vehicle-treated males, P < 0.05

Fig. 2

The effects of 0, 5 or 10 days treatment with vehicle (VEH), 0.5 (LOW) or 5 μg/g/day(HIGH) of the mixed D₁/D₂ receptor antagonist, cis-flupenthixol on social behavior and activity (Mean ± SEM) in zebra finches. While these graphs present mean behavioral frequencies (± SEM) for each test, the social behavior analyses were run on difference scores, subtracting each bird’s score on its initial pre-drug test from its scores on each drug test (See Data Analysis). Note that the total frequencies on the Y axes differ between some of the graphs. ^HSignificantly different from high-dose males, P < 0.05. ^HHSignificantlydifferent from high-dose males, P < 0.01, ^HHHSignificantly different from high-dose males, P < 0.001. ^vSignificantly different from vehicle-treated males, P < 0.05