Precopulatory behaviour in the male hamster: effect of the 5α-reductase inhibitor 17β-N,N-diethylcarbamoyl-4-aza-5α-androstan-3-one

Abstract

Three independent components of hamster masculine behaviour (approaching, leaving and sniffing the female) have been shown to depend on both androgenic and oestrogenic action. The behavioural role of 5 alpha-reduced androgens was assessed by blocking 5 alpha-reduction of testosterone by means of 17 beta-N,N-diethylcarbamoyl-4-aza-5 alpha-androstan-3-one (4-MA) through slow-release silicone elastomer implants. Three dose levels of 4-MA were given to intact, sexually active males. The probability of approaching the female and the amount of sniffing directed to her were both decreased, while the probability of leaving the female was increased. Sniffing and the tendency to approach were affected at lower dose levels than was the tendency to leave. The higher dosage of 4-MA also abolished odour-based discrimination between females shown by normal males. These effects of 4-MA on behaviour were confirmed in castrated hamsters maintained on testosterone. The suppressive effects of 4-MA on behaviour were reversed by treatment with 5 alpha-dihydrotestosterone (DHT). We conclude that testosterone maintains sociosexual behaviour in part by conversion to its 5 alpha-reduced metabolites; components of this behaviour differ in their relative dependence on DHT. In this species, DHT is likely to be a behaviourally active metabolite of testosterone involved in the fine control of behaviour.

Androgen Metabolism in the Brain of the Green Anole Lizard (Anolis carolinensis): Effects of Sex and Season

“…For example, DHT can reinstate masculine calling and amplectic clasping in amphibians (Kelley and Pfaff, 1976;Moore and Miller, 1983;Wetzel and Kelley, 1983;Penna et al, 1992) and copulatory postures in whiptail lizards (Lindzey and Crews, 1986;Mayo and Crews, 1987;Wade et al, 1993). In other species, treatment with 5␣-reductase inhibitors attenuates T-mediated behaviors, such as chemoinvestigation in male hamsters (Steel and Hutchison, 1988) and penile erections in rats (Bradshaw et al, 1981).…”

Reduction of Proliferating Olfactory Cells and Low Expression of Extracellular Matrix Genes Are Hallmarks of the Aged Olfactory Mucosa

“…In addition, a histological analysis using Col-GFP mice revealed that type 1 collagen levels are decreased in the nasal mucosa of aged mice; thus, the quantity and quality of collagen-expressing mesenchymal cells might change with age. Despite clinical evidence that olfaction decreases with age, the mechanism underlying the upregulation of genes involved in olfactory transduction has yet to be definitively determined; however, it is speculated to be a compensatory response to olfactory impairment or an increase in the expression of genes in the nasal mucosa involved in olfactory transduction, such as Syt10 (Cao et al, 2011 ), Bpifb9b (Kuntová et al, 2018 ), and Srd5a2 (Steel and Hutchison, 1988 ).…”