Regulation by the Medial Amygdala of Copulation and Medial Preoptic Dopamine Release

Abstract

The medial preoptic area (MPOA) is a critical integrative site for male copulatory behavior in most vertebrate species. Extracellular dopamine (DA) is increased in the MPOA of male rats immediately before and during copulation. DA agonists microinjected into the MPOA of male rats facilitate and DA antagonists inhibit sexual behavior. A major source of input to the MPOA is the medial amygdala (MeA), which processes and relays olfactory information to the MPOA. We now report that microinjections of a DA agonist into the MPOA of animals with excitotoxic lesions of the amygdala restored copulatory ability that was lost after the lesions. Moreover, radio-frequency lesions of the MeA impaired copulation and blocked the increases in extracellular DA seen in animals with sham lesions during exposure to a receptive female and during copulation. Thus, both copulatory ability and the MPOA DA response, during exposure to a receptive female and during copulation, are facilitated by input from the MeA to the MPOA.

Dopamine, the medial preoptic area, and male sexual behavior

“…Lesions significantly decreased all aspects of copulation. Microinjections of apomorphine, but not vehicle, into the MPOA of animals with amygdala lesions restored copulation [87]. This finding suggests that the amygdala facilitates copulation by increasing DA activity in the MPOA.…”

“…Values are expressed as mean T SEM, *P < 0.05; **P < 0.01 (Reprinted from Ref. [87], with permission).…”

“…Therefore, in the second set of experiments, using microdialysis and HPLC-EC, we measured mating-induced DA activity in the MPOA of animals with MeA lesions or sham lesions. Results showed that MeA lesions again impaired copulation, as animals with lesions displayed fewer ejaculations and required more time and more intromissions to reach an ejaculation; these animals also displayed longer PEIs [87]. Analyses of dialysate samples collected from the MPOA of animals with sham lesions showed increases of extracellular DA in the MPOA during exposure to an estrous female and during copulation, consistent with previous reports (see above); however, analyses of samples from animals with lesions did not reveal such an increase, although basal DA levels were normal [87] (see Fig.…”

Fos responses of dopamine neurons to sociosexual stimuli in male zebra finches

“…This colocalization decreased in response to all conspecific stimuli except fighting, and did not decrease following exposure to a heterospecific male. Keywords dopamine; forebrain; aggression; sexual behavior; tyrosine hydroxylase; Fos Dopamine (DA) is known to influence a variety of social behaviors, particularly male sexual behavior, in multiple vertebrate groups (Warner et al, 1991;Pomerantz, 1992;Absil et al, 1994;Hull et al, 1995;Dominguez et al, 2001;Woolley et al, 2001;Melis et al, 2003;Charlier et al, 2005), and DA cells are distributed in homologous groups across the vertebrate classes (Bailhache and Balthazart, 1993;Bottjer, 1993;Gonzalez and Smeets, 1994;Reiner et al, 1994;Tillet, 1994;Appeltants et al, 2001;Adrio et al, 2002). This similarity across vertebrates is particularly clear when comparing mammals and birds, which each have dopaminergic neurons (immunopositive for tyrosine hydroxylase, TH, and immunonegative for dopamine β-hydroxylase) localized to eight populations of the basal forebrain and brainstem numbered A8 through A15 (Reiner et al, 1994;Tillet, 1994).…”

“…Extensive data suggest that the release of DA into the preoptic area (POA) controls male sexual behavior. Administrations of the DA agonist apomorphine into the medial POA facilitate sexual behavior in male rats (Hull et al, 1986;Dominguez et al, 2001), whereas injections of the DA antagonist cis-flupenthixol into the medial POA reduce ejaculations, copulation rate, erections and penile movements before copulation, and sexual motivation (Pehek et al, 1988;Warner et al, 1991). Extracellular DA in male rats is increased in the medial POA during copulation and exposure to a receptive female (Hull et al, 1995), and in the paraventricular nucleus of the hypothalamus during copulation (Melis et al, 2003).…”