Opposite influence of medial preoptic D1 and D2 receptors on genital reflexes: Implications for copulation

A Nitric Oxide Synthesis Inhibitor Administered Into the Medial Preoptic Area Increases Seminal Emissions in an Ex Copula Reflex Test

“…However, we have previously reported that low doses of a dopamine D 2 / D 3 agonist (quinelorane) decreased the latency to the first erection without affecting the number of erections; higher doses also decreased the latency to the first erection, but actually decreased the number of erections (9). Thus, a decrease in latency may not indicate a facilitation of erection.…”

Dopamine, the medial preoptic area, and male sexual behavior

“…In this same study, a low dose of apomorphine increased erections, and this effect was fully blocked by the D 1 antagonist SCH-23390 and partially blocked by the D 2 antagonist raclopride, suggesting that both receptor types contributed to apomorphine's effects, but that the D 1 receptor was more efficacious. On the other hand, a high dose of apomorphine increased seminal emissions, and this effect was blocked by the D 2 antagonist raclopride and slightly enhanced by the D 1 antagonist SCH-23390 [82], suggesting that potent stimulation of D 2 -like receptors may shift the autonomic balance to favor seminal emission and inhibit erection. Therefore, D 1 and D 2 receptors in the MPOA have different thresholds of activation and different effects on autonomic control of genital reflexes.…”

“…Though the nature of this disinhibition is not known, one possibility is that D 2 dopamine receptors exist on GABA containing neurons in the MPOA; therefore stimulation of these D 2 receptors would inhibit GABA release downstream from the MPOA. Stimulation of D 1 receptors using dihydroxyphenyl-tetrahydrothienopyridine (THP; a D 1 receptor full agonist) increased the number of ex copula erections but decreased the number of seminal emissions; conversely a D 1 antagonist (SCH-23390) had the opposite effects, decreased erections and increased seminal emissions [82]. Therefore, stimulation of D 1 -like receptors may provide the ''engine'' for erections.…”

The neurobiology of social attachment: A comparative approach to behavioral, neuroanatomical, and neurochemical studies

“…Further, the DA regulation of pair bonding is sub-region specific within the NAcc, as activation of D2Rs in the NAcc shell, but not the core, induces partner preference formation . Interestingly, this receptor-and region specific DA regulation has also been known to mediate other behaviors, such as copulation and drug-seeking behavior (Hull et al, 1992;Self et al, 1996;Graham et al, 2007).…”