Colocalization of Mating-Induced Fos and D2-Like Dopamine Receptors in the Medial Preoptic Area: Influence of Sexual Experience

Abstract

Dopamine in the medial preoptic area (mPOA) stimulates sexual activity in males. This is evidenced by microdialysis and microinjection experiments revealing that dopamine receptor antagonists in the mPOA inhibit sexual activity, whereas agonists facilitate behavior. Microdialysis experiments similarly show a facilitative role for dopamine, as levels of dopamine in the mPOA increase with mating. While the majority of evidence suggests an important role for dopamine receptors in the mPOA in the regulation of male sexual behaviors, whether sexual activity or sexual experience influence dopamine receptor function in the mPOA has not been previously shown. Here we used immunohistochemical assays to determine whether varying levels of sexual activity or experience influence the number of cells containing Fos or D2 receptor immunoreactivity. Results show that sexual experience facilitated subsequent behavior, namely experience decreased latencies. Moreover, the number of cells with immunoreactivity for Fos or D2 correlated with levels of sexual experience and sexual activity. Sexual activity increased Fos immunoreactivity. Sexually experienced animals also had significantly more D2-positive cells. Sexually inexperienced animals copulating for the first time had a larger percentage of D2-positive cells containing Fos, when compared to sexually experienced animals. Finally, regardless of experience, animals that had sex prior to sacrifice had significantly more D2-positive cells that contained Fos, vs. animals that did not copulate. These findings are noteworthy because sexually experienced animals display increased sexual efficiency. The differences in activation of D2 and changes in receptor density may play a role in this efficiency and other behavioral changes across sexual experience.

Distribution of corticotropin-releasing factor receptor 1 in the developing mouse forebrain: A novel sex difference revealed in the rostral periventricular hypothalamus

“…Across development, CRFR1-GFP-ir within the MPOA was stable between P0 and P21. The MPOA is known to have anatomical sex differences (Morris et al, 2004), and influence sexual behavior in rodents (Nutsch et al, 2016). Although, no obvious sex differences in receptor protein were apparent, previous work in rats has demonstrated a sex difference in MPOA CRF, with females exhibiting a higher density (McDonald et al, 1994;Funabashi et al, 2004).…”

Cellular Composition of the Preoptic Area Regulating Sleep, Parental, and Sexual Behavior

“…MPOA neurons also mediate experience-dependent sexual arousal. Sexual experience facilitates all components of mating behaviors, and this facilitation is thought to be mediated by experience-induced changes in MPOA neurons, such as synaptic plasticity ( Jean et al, 2017 ), dopamine sensitivity ( McHenry et al, 2012 ; Nutsch et al, 2016 ), oxytocin sensitivity ( Gil et al, 2013 ), and neuropeptide precursor expression ( Maejima et al, 2018 ).…”

The Sexual Motivation of Male Rats as a Tool in Animal Models of Human Health Disorders

“…MPOA is one of the brain structures in which acquisition of sexual experience leads to an increase in Fos expression, and higher levels of neurotransmitters, receptors, or enzymes and hormones important for regulation of sexual activity (Hull and Rodríguez-Manzo, 2017). Specifically, it was shown that acquisition of sexual experience is associated with an increase in nitric oxide with higher levels of nitric oxide synthase (Dominguez et al, 2006), glutamate and dopamine (Will et al, 2014), D1 receptor signaling (McHenry et al, 2012) and D2 receptor signaling (Nutsch et al, 2016), and oxytocin receptors (Gil et al, 2013), and an increased number of neurons containing androgen receptors (Swaney et al, 2012). Moreover, acquisition of sexual experience and improvement in copulatory efficiency was shown to involve neuronal plasticity as measured by c-fos expression in the parieto-occipital cortex (Bialy et al, 1992;Bialy and Kaczmarek, 1996).…”