Men who socialise more produce less testosterone than men who live an isolated existence. It’s possible to deduce this from an animal study that researchers at the University of Padova in Italy published recently in Steroids.
Social environment determines to a large extent the amount of testosterone that men produce. Athletes, for example, produce more testosterone when they win a competition – especially if it’s a home meeting. Even just thinking about previous conquests can boost athletes’ testosterone levels.
That’s why biologists sometimes refer to testosterone as ‘the winners’ hormone’.
According to the Italians, this view of matters is not entirely correct. They measured the hormone levels in the blood of two groups of mice. One group had lived from birth in a cage with five other mice; the other group lived in individual cages.
When, after two and six months, the researchers measured the amount of testosterone and DHEA [structural formulas shown here] circulating in the mice’s bodies, they observed on both occasions that the mice living in isolation manufactured three times as much testosterone. The DHEA concentration was also higher in the isolated animals. So testosterone is not just the ‘winners’ hormone’ but also the ‘hormone of the lonely’.
The researchers suspect that living in groups is stressful for animals, and that this causes their testosterone level to decrease.
Before the advent of synthetic testosterone it was not unusual for athletes, strongmen and gladiators to live in relative isolation, devoting themselves to their sport or discipline away from society. Perhaps the Italian study helps understand why this was so.
Age and isolation influence steroids release and chemical signaling in male mice.
Mucignat-Caretta C1, Cavaggioni A2, Redaelli M2, Da Dalt L3, Zagotto G4, Gabai G3.
Social interactions in mice involve olfactory signals, which convey information about the emitter. In turn, the mouse social and physiological status may modify the release of chemical cues. In this study, the influences of age and social isolation on the endocrine response and the release of chemical signals were investigated in male CD1 mice, allocated into four groups: Young Isolated (from weaning till 60days; N=6), Adult Isolated (till 180days; N=6), Young Grouped (6 mice/cage; till 60days; N=18), Adult Grouped (6 mice/cage; till 180days; N=18). Mice were transferred in a clean cage to observe the micturition pattern and then sacrificed. Body and organs weights, serum testosterone, dehydroepiandrosterone, corticosterone and the ratio Major Urinary Protein/creatinine were measured. Urinary volatile molecules potentially involved in pheromonal communication were identified. Androgen secretion was greater in isolated mice (P<0.05), suggesting a greater reactivity of the Hypothalamic-Pituitary-Gonadal axis. Grouped mice presented a higher degree of adrenal activity, and young mice showed a higher serum corticosterone (P<0.05) suggesting a greater stimulation of the Hypothalamic-Pituitary-Adrenal axis. The micturition pattern typical of dominant male, consisting in voiding numerous droplets, was observed in Young Isolated mice only, which showed a higher protein/creatinine ratio (P<0.05). Urinary 2-s-butyl-thiazoline was higher in both Young and Adult Isolated mice (P<0.005). Young Isolated mice showed the most prominent difference in both micturition pattern and potentially active substance emission, while long term isolation resulted in a less extreme phenotype; therefore social isolation had a higher impact on young mice hormone and pheromone release.
PMID: 24525008 [PubMed – as supplied by publisher]