Differential effects of central injections of D1 and D2 receptor agonists and antagonists on male sexual behavior in Japanese quail

Abstract

A key brain site in the control of male sexual behavior is the medial pre-optic area (mPOA) where dopamine stimulates both D1 and D2 receptor subtypes. Research completed to date in Japanese quail has only utilized systemic injections and therefore much is unknown about the specific role played by dopamine in the brain and mPOA in particular. The present study investigated the role of D1 and D2 receptors on male sexual behavior by examining how intracerebroventricular injections and microinjections into the mPOA of D1 and D2 agonists and antagonists influenced appetitive and consummatory aspects of sexual behavior in male quail. Experiments 1 and 2 investigated the effects of intracerebroventricular injections at three doses of D1 or D2 agonists and antagonists. The results indicated that D1 receptors facilitated consummatory male sexual behavior, whereas D2 receptors inhibited both appetitive and consummatory behaviors. Experiment 3 examined the effects of the same compounds specifically injected in the mPOA and showed that, in this region, both receptors stimulated male sexual behaviors. Together, these data indicated that the stimulatory action of dopamine in the mPOA may require a combined activation of D1 and D2 receptors. Finally, the regulation of male sexual behavior by centrally infused dopaminergic compounds in a species lacking an intromittent organ suggested that dopamine action on male sexual behavior does not simply reflect the modulation of genital reflexes due to general arousal, but relates to the central control of sexual motivation. Together, these data support the claim that dopamine specifically regulates male sexual behavior.

Figure 1

Mean (± SEM) RCSM frequency observed before and during visual access to a female in male quail that had been injected ICV with Saline (S) or with a Low (L), Medium (M) or High (H) dose of the D1 agonist SKF-38393 (a), the D1 antagonist SCH-23390 (b), the D2 agonist Quinpirole (c) or the D2 antagonist Raclopride (d). (a)= p<0.05 for comparison versus Saline.

Figure 2

Mean (± SEM) frequency (left) and latency (right) of CCM observed during tests performed immediately after the measure of RCSM in male quail that had been injected ICV with Saline (S) or with a Low (L), Medium (M) or High (H) dose of the D1 agonist SKF-38393. (a), (b), (c) = p<0.05 for comparison versus Saline (a), Low (b), and Medium (c) doses.

Figure 3

Mean (± SEM) frequency (left) and latency (right) of CCM observed during tests performed immediately after the measure of RCSM in male quail that had been injected ICV with Saline (S) or with a Low (L), Medium (M) or High (H) dose of the D1 antagonist SCH-23390. (a) = p<0.05 for comparison versus Saline.

Figure 4

Mean (± SEM) frequency (left) and latency (right) of CCM observed during tests in the large arena (no RCSM test before) in male quail that had been injected ICV with Saline (S) or with a Low (L), Medium (M) or High (H) dose of the D2 antagonist Raclopride. (a), (b) = p<0.05 for comparison versus Saline (a) and Low (b) dose.

Figure 5

Mean (± SEM) frequency (left) and latency (right) of NG observed during tests performed immediately after the measure of RCSM in male quail that had been injected ICV with Saline (S) or with a Low (L), Medium (M) or High (H) dose of the D2 agonist Quinpirole. (c) = p<0.05 for comparison versus the Medium dose.

Figure 6

Mean (± SEM) RCSM frequency observed before and during visual access to a female in male quail that had been microinjected in the mPOA with Saline, the D1 agonist SKF-38393, the D1 antagonist SCH-23390, the D2 agonist Quinpirole or the D2 antagonist Raclopride. (a), (b), (d) = p<0.05 for comparison versus Saline (a), SKF-38393 (b), and Quinpirole (d).

Figure 7

Mean (± SEM) frequency (left) and latency (right) of M observed in male quail that had been microinjected in the mPOA with Saline, the D1 agonist SKF-38393, the D1 antagonist SCH-23390, the D2 agonist Quinpirole or the D2 antagonist Raclopride. (a), (b), (d) = p<0.05 for comparison versus Saline (a), SKF-38393 (b), and Quinpirole (d).