Bilateral damage to the sexually dimorphic medial preoptic area/anterior hypothalamus of male ferrets causes a female-typical preference for and a hypothalamic Fos response to male body odors

Abstract

Previous studies showed that bilateral lesions of the male ferret's preoptic area/anterior hypothalamus (POA/AH), centered in the sexually dimorphic nuclei present in this region, caused subjects to seek out a same-sex male, as opposed to a female conspecific. Male subjects with POA/AH lesions (which were also castrated and given estradiol) displayed female-typical receptive behavior in response to neck gripping by a stimulus male, implying that subjects' approaches to a same-sex conspecific were sexually motivated. We asked whether the effect of POA/AH lesions on males' partner preference reflects a shift in the central processing of body odorant cues so that males come to display a femaletypical preference to approach male body odorants. Sexually experienced male ferrets in which electrolytic lesions of the POA/AH caused bilateral damage to the sexually dimorphic male nucleus (MN) resembled sham-operated females by preferring to approach body odors emitted from anesthetized male as opposed to female stimulus ferrets confined in the goal boxes of a Y-maze. This lesion-induced shift in odor preference was correlated with a significant increase in the ability of soiled male bedding to induce a Fos response in the medial POA of males with bilateral damage to the MN-POA/AH. No such partner preference or neural Fos responses were seen in sham-operated males or in other groups of males with POA/AH lesions that either caused unilateral damage or no damage to the MN-POA/AH. Male-typical hypothalamic processing of conspecifics' body odorants may determine males' normal preference to seek out odors emitted by female conspecifics, leading to mating and successful reproduction.

Roles of sex and gonadal steroids in mammalian pheromonal communication

“…of neurons in the POA/AH, male subjects would display the default, female-typical preference to seek out male odors. This hypothesis was confirmed in a study (Alekseyenko et al, 2007) showing that bilateral lesions of the male nucleus of the POA/AH in male ferrets caused them to prefer to approach volatile body odors from other male ferrets. These lesioned ferrets also showed a female-like profile of rostral medial POA Fos responses to volatile male odors.…”

Topography in the preoptic region: Differential regulation of appetitive and consummatory male sexual behaviors

“…Lesions of the mPOA diminish preference for a female partner in rats and ferrets [7,65,105,106], decrease pursuit of the female by male rats [104], and decrease anticipatory erections and anogenital investigations in marmosets [91]. Furthermore, in vivo dialysis experiments have revealed that sexual interactions progressively increase the level of extracellular dopamine in the mPOA of male rats and this increase begins as soon as the male is introduced to the female and initiates pursuits and anogenital investigations, i.e., several minutes before the beginning of copulatory interactions (consummatory responses) sensu stricto [79].…”

Developmental programming and endocrine disruptor effects on reproductive neuroendocrine systems

“…Another group reported that SDN-POA lesions in male rats decreased the percentage of animals that ejaculated in a mating test, and increased latencies to mount, intromit, or ejaculate [41]. Although an exact homolog of the SDN-POA may not exist in other species, there is evidence for sexual dimorphism of the anterior hypothalamus and preoptic area in other species that have been studied [152,22,111,2], making the SDN-POA of the rat a valuable comparative model.…”