Sexually Dimorphic Activation of Galanin Neurones in the Ferret's Dorsomedial Preoptic Area/Anterior Hypothalamus after Mating

Abstract

Male ferrets in breeding condition possess three times as many galanin-immunoreactive (IR) neurones as oestrous females in the sexually dimorphic dorsomedial preoptic area/anterior hypothalamus (dmPOA/AH). Using Fos-IR as a marker of activation, we investigated whether mating with intromission differentially activates this sexually dimorphic group of galanin-IR neurones in male and female ferrets. Male ferrets that intromitted had a significantly greater percentage of galanin-IR neurones in the dmPOA/AH that were colabelled with nuclear Fos-IR than oestrous females that received an intromission. Intromissive stimulation augmented Fos-IR in an equal percentage of galanin-IR neurones in both sexes in the medial amygdala (MA) and bed nucleus of the stria terminalis (BNST). Peripheral anosmia induced by bilateral occlusion of males' nares did not reduce the mating-induced activation of galanin-IR neurones in the dmPOA/AH, and there was a significant correlation among individual males between intromission duration and the percentage of dmPOA/AH galanin-IR neurones colabelled with Fos-IR. Exposure of castrated, testosterone propionate-treated male ferrets to either soiled bedding or to volatile odours from oestrous females failed to induce nuclear Fos-IR in galanin-IR neurones located in the dmPOA/AH, BNST or MA, suggesting that the mating-induced activation of galanin-IR forebrain neurones in male ferrets depends more on genital-somatosensory than on olfactory inputs. The observed sex dimorphism in the mating-induced activation of galanin-IR neurones in the dmPOA/AH raises the possibility that these neurones perform a mating-dependent function that occurs only in males.

Estrogen‐receptor‐β distribution in the human hypothalamus: Similarities and differences with ERα distribution

“…and its stronger nuclear ERβ‐expression in young adult men (present study) is related to ERβ's potential role in the prevention of neuronal cell death (Wang et al, 2001), awaits future investigations. From a functional point of view, it is conceivable, e.g., that the sexually dimorphic presence of ARs and both ERs in the human SDN‐POA points to the possible involvement of the human mPOA in gender‐dependent aspects of sexual behavior and aggression, as has been reported for animals (Ogawa et al, 2000; Wang et al, 1997; Gregg and Siegel, 2001; Bakker et al, 2002; Blaustein and Greco, 2002; Fernández‐Guasti et al, 2002).…”

“…The mPOA contains the SDN‐POA (= SDN‐mPOA or INAH‐1) and other INAH cell clusters. The mPOA becomes activated during mating (Blaustein and Greco, 2002; Bakker et al, 2002) and has been implicated in certain aspects of male sexual behavior (e.g., copulation and sexual exhaustion) and aggression (DeJonge et al, 1989; Swaab, 1997; Wang et al, 1997; Gregg and Siegel, 2001; Fernández‐Guasti et al, 2002). The SDN‐POA is sexually dimorphic in the rodent and human brain, with males having a larger volume and neuron number (Gorski et al, 1978; Swaab and Fliers, 1985; Swaab and Hofman, 1988; Hofman and Swaab, 1989).…”

Galanin neurons in the intermediate nucleus (InM) of the human hypothalamus in relation to sex, age, and gender identity

“…The function of galanin neurons in the human InM is not known, but animal experiments suggest that this area and its galanin neurons in particular may be involved in sexual and reproductive behavior (Swaab, 2003, 2004a). In the ferret the medial preoptic galanin neurons are activated during mating (Bakker et al, 2002), and the galanin production of the InM neurons of the ferret is activated by testosterone (Park et al, 1997). The SDN‐POA size in rats is positively correlated with the frequency of masculine sexual behavior, as well as with male preference for a female over a male (Houtsmuller et al, 1994).…”

Galanin neurons in the medial preoptic area govern parental behaviour

“…2a-2e), suggesting that a common pathway for parental behavior exists in males and females that is normally repressed in virgin males by vomeronasal inputs. The ventral BNST/dorsal MPOA was shown to play an important role in rat maternal behavior 12,22 , but also in sexual behavior 23–27 , thermoregulation 28 , and GnRH secretion 29 . Accordingly, we observe robust MPOA c-fos activation after mating, medial to the area containing parenting-induced c-fos (Figs.…”