Discussion
The present experiments demonstrate that administration of a D1 antagonist into the MPOA
before each of 7 daily noncopulatory female exposures resulted in impaired sexual function
on the subsequent drug-free copulation test on day 8, compared to combined controls with
exposure. Additionally, drug-treated animals with misplaced cannulae outside the MPOA
displayed no differences in copulatory behavior, compared to vehicle-treated femaleexposed
animals, indicating that this is a site-specific action. We also replicated our previous
findings, demonstrating that repeated noncopulatory female exposures facilitate subsequent
copulatory performance in vehicle-treated animals (Lagoda et al., 2004; Powell et al., 2003;
Vigdorchik et al., 2012). Furthermore, no differences in locomotor activity were found
between groups on the copulation test day; thus, it is unlikely that the copulatory
impairments resulted from deficits in motor activity. Lastly, there was more p-DARPP-32 in
the MPOA of experienced males that copulated on the day of euthanasia (ES), compared to
all other groups. Therefore, chronic sexual experience imparts changes in mating-induced
phosphorylation of DARPP-32 in the MPOA that may be mediated by D1 receptors, as
discussed below.