Rapid stimulatory effects of testosterone upon myotubule metabolism and sugar transport, as assessed by silicon microphysiometry

Abstract

A considerable number of studies have revealed behavioral circumstances that give rise to small or transient differences in circulating testosterone concentrations; however, careful consideration of androgen physiology leads to the disquieting conclusion that these differences are often unlikely to have much physiologic or behavioral significance. In the present report, we observe that small transients of testosterone secretion could have very rapid anabolic effects on a cultured muscle‐derived cell line. Specifically, we have examined the effects of testosterone on metabolism in cultured C2C12 myotubules, using a silicon microphysiometer. The instrument monitors cellular extrusion of protons and acidic metabolites, and such extrusion is directly linked to ATP hydrolysis, thus providing a real‐time measure of cellular metabolism. Testosterone caused a small but significant increase in metabolism. The most striking feature of this effect was its rapidity, in that it occurred within 3 hr. This rapid enhancement of metabolism suggested that testosterone might be enhancing substrate uptake even more rapidly. Indeed, we found that testosterone increased 2‐deoxyglucose uptake within 1 min. The rapidity of this effect seemed to preclude mediation by classical intracellular steroid receptors. In support of this, we were unable to detect specific intracellular binding of testosterone. These findings show that testosterone can exert rapid anabolic effects on substrate transport and metabolism in myotubules. Should this finding general to muscle in vivo, it suggests that relatively small individual differences in testosterone profiles, in response to various social interactions, may have very real consequence for subsequent muscle physiology. © 1996 Wiley‐Liss, Inc.

Costly steroids: egg testosterone modulates nestling metabolic rate in the zebra finch

“…We do not know whether egg treatment caused differences in circulating hormone levels in the nestlings, but higher blood levels of testosterone or related steroids may result in higher metabolic rates as has been found in adult birds and fishes (Buchanan et al 2001;Ros et al 2004). Moreover, testosterone is also known to increase anabolic processes at the cellular level ( Tsai & Sapolsky 1996).…”

Effects of Implicit Power Motivation on Men's and Women's Implicit Learning and Testosterone Changes After Social Victory or Defeat.

“…Sapolsky (1987) has provided another plausible explanation. T induces rapid increases in muscle anabolism (Tsai & Sapolsky, 1996) and lowers the threshold for dominance-related aggression mediated by structures of the "emotional brain" (LeDoux, 1996) such as the septum and the amygdala (Albert, Jonik, & Walsh, 1992). According to Sapolsky, increases in physical strength and aggressiveness associated with high rank or victory make an individual more physically fit and motivated to attain or retain high social rank.…”

“…For instance, Dabbs and his collaborators reported that in female prison inmates, those with a more extensive record of aggressive behavior are higher in T (Dabbs & Hargrove, 1997) and that among adolescents, high-T girls are just as prone as high-T boys to engage in antisocial, rebellious behavior (Banks & Dabbs, 1996). Moreover, in a carefully designed double-blind study, van Honk et al (2001) showed that women treated with T showed a stronger cardiovascular response than women treated with placebo to perceived facial expressions of anger-a dominance signal (cf. Knutson, 1996)but not to happy or neutral faces.…”

Reproductive ecology and life history of the human male

“…Indeed, Tsai and Sapolsky (1996) proposed that short-term changes in testosterone levels, such as those observed in competition, may involve energy mobilization in muscle cells. They reported a 25% increase in metabolic rate in muscle cells in vitro within 1 min of exposure to testosterone.…”