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A pacing paradigm investigated the modulatory role of monoamines in the mesolimbic dopamine system on copulatory behavior in female mice. Specifically whether there is a distinction between the neural regulatory mechanisms of pacing behavior and receptive behavior was determined. Pacing measures motivational and rewarding components of copulation by the female's contacts and withdrawals from the male, while receptivity is the willingness to engage in copulations and is measured by the number of sexual stimulations received. A pacing paradigm was established and female mice were observed to pace in a similar manner, but at a lesser rate, than female rats.
Dopamine (DA) and its pathways regulate copulatory behaviors in female rats. General and specific DA receptor agonists were used to investigate dopaminergic mediation of copulatory behavior in female mice. Three doses of apomorphine (APO; 20mug, 60 mug and 120 mug/kg), a general dopamine agonist, were given and resulting effects on pacing behavior, receptive behavior, and dopamine and metabolite levels in brain areas measured. Treatment caused dose dependent increases in pacing and in DA levels in the Nacc and significantly lower levels of HVA/DA in the striatum and Nacc. There results are consistent with previous studies in rats that show activation of DA terminals in there areas during reward. The lowest effective dose for altering pacing was 120mug/kg. APO treatment was associated with dose dependent decreases in receptivity and significant increases of HVA in the VMN with a lowest effective dose of 60mug/kg. The VMN is the CNS regulatory center for receptivity. Since pacing behavior involves locomotor behavior and APO affects locomotion, subjects were treated with APO and locomotion, anxiety and exploratory behavior were measured using an open field. APO dependent increases in locomotion and anxiety and decreases in exploratory behavior may contribute to its modulation of copulatory behaviors.
In conclusion, a pacing paradigm was established for mice, and results showed differential effects of DA (dose and brain region) on regulation of motivational and rewarding vs. receptive components of female sexual behavior. This information can be utilized in clinical research on sexual dysfunction and drug abuse involving the DA mesolimbic "reward" pathway.
Hodges, Amber Bradshaw, "The Role of Dopamine in Motivational and Receptive Aspects of Female Mouse Sexual Behavior" (2004). CUNY Academic Works.