Relationships between testosterone metabolism in the brain, other endocrine variables and intermale aggression in mice

Abstract

Relationships between some endocrine variables (plasma testosterone and estradiol; in vitro gonadal biosynthesis from pregnenolone precursor and adrenocortical biosynthesis from progesterone precursor; in vitro activity of 17β‐hydroxysteroid de‐hydrogenase (17β‐HSDH) and of aromatizing enzymes in the subcellular fractions of the brain) and isolation‐induced inter‐male aggressiveness were studied. A significant positive correlation was found between fighting behavior, measured by the number of wins in a series of paired encounters, and the activity of brain 17β‐HSDH. A significant inverse correlation was found between fighting behavior and the activity of aromatizing enzymes in the nuclear fraction of the brain. No significant correlations were found between fighting and the other endocrine variables investigated. These results may suggest that the conversions testosterone → androstenedione and testosterone → estradiol in the brain play a role in the control of inter‐male fighting in the mouse. These results may also account for the effect of repeated wins and defeats on brain steroidogenesis.

Stress enhances aggression in male rats with genetic stress hyper‐reactivity

“…44 Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior. 45 The potential role of brain-derived estrogen in the stress-induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

“…Testosterone can be either aromatized by Cyp19a1 to estradiol or 5α‐reduced into the non‐aromatizable dihydrotestosterone (DHT) in target tissues, 43 but estradiol levels are 10‐fold higher than that of DHT in male rats 44 . Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior 45 . The potential role of brain‐derived estrogen in the stress‐induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

Stress enhances aggression in male rats with genetic stress hyper‐reactivity

“…44 Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior. 45 The potential role of brain-derived estrogen in the stress-induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

“…Testosterone can be either aromatized by Cyp19a1 to estradiol or 5α‐reduced into the non‐aromatizable dihydrotestosterone (DHT) in target tissues, 43 but estradiol levels are 10‐fold higher than that of DHT in male rats 44 . Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior 45 . The potential role of brain‐derived estrogen in the stress‐induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

Inhibition of Steroid Receptor Coactivator-1 Blocks Estrogen and Androgen Action on Male Sex Behavior and Associated Brain Plasticity

“…Few studies have been able to correlate the behavioral effectiveness of steroid hormones with the concentration of their receptors in a particular brain area (Clark et al, 1985;Balthazart et al, 1996b). Variation in the efficiency of steroid-metabolizing enzymes or in the availability of steroid receptors has also been implicated in some cases (Dessi-Fulgheri et al, 1976;Balthazart et al, 2004). The findings described in this paper indicate that coactivators such as SRC-1 represent another class of proteins that are important for regulating steroid action in adulthood on brain and behavior.…”

Behavioral and physiological correlates of aggressive dominance in male brown lemmings (Lemmus sibiricus)

“…Although plasma T levels have been shown to be related to individual differences in aggressiveness in rhesus monkeys [e.g., Rose et al, 1971;19721, most attempts to find similar correlations in intact rodents have failed [e.g., BUM, 1976;Dessi-Fulgheri et al, 1976;Selmanoff et al, 1977;Sachser and Prove, 19841. One possible reason for this failing may be the pulsatile nature of T secretion in the latter species [Bartke et al, 1973;Mock et al, 19781.…”

Stress enhances aggression in male rats with genetic stress hyper‐reactivity

“…44 Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior. 45 The potential role of brain-derived estrogen in the stress-induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

“…Testosterone can be either aromatized by Cyp19a1 to estradiol or 5α‐reduced into the non‐aromatizable dihydrotestosterone (DHT) in target tissues, 43 but estradiol levels are 10‐fold higher than that of DHT in male rats 44 . Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior 45 . The potential role of brain‐derived estrogen in the stress‐induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

Inhibition of Steroid Receptor Coactivator-1 Blocks Estrogen and Androgen Action on Male Sex Behavior and Associated Brain Plasticity

“…Few studies have been able to correlate the behavioral effectiveness of steroid hormones with the concentration of their receptors in a particular brain area (Clark et al, 1985;Balthazart et al, 1996b). Variation in the efficiency of steroid-metabolizing enzymes or in the availability of steroid receptors has also been implicated in some cases (Dessi-Fulgheri et al, 1976;Balthazart et al, 2004). The findings described in this paper indicate that coactivators such as SRC-1 represent another class of proteins that are important for regulating steroid action in adulthood on brain and behavior.…”

Behavioral and physiological correlates of aggressive dominance in male brown lemmings (Lemmus sibiricus)

“…Although plasma T levels have been shown to be related to individual differences in aggressiveness in rhesus monkeys [e.g., Rose et al, 1971;19721, most attempts to find similar correlations in intact rodents have failed [e.g., BUM, 1976;Dessi-Fulgheri et al, 1976;Selmanoff et al, 1977;Sachser and Prove, 19841. One possible reason for this failing may be the pulsatile nature of T secretion in the latter species [Bartke et al, 1973;Mock et al, 19781.…”

Stress enhances aggression in male rats with genetic stress hyper‐reactivity

“…44 Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior. 45 The potential role of brain-derived estrogen in the stress-induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

“…Testosterone can be either aromatized by Cyp19a1 to estradiol or 5α‐reduced into the non‐aromatizable dihydrotestosterone (DHT) in target tissues, 43 but estradiol levels are 10‐fold higher than that of DHT in male rats 44 . Although A4 is thought of as a weak androgen, it can also be converted by Cyp19a1 into the weak estrogen, estrone, in the periphery and in the brain, thereby has relevance for aggressive behavior 45 . The potential role of brain‐derived estrogen in the stress‐induced aggression of WMIs is further supported by the finding of increased FCX expression of both estrogen receptors in WMIs after prior stress in the current study.…”

Inhibition of Steroid Receptor Coactivator-1 Blocks Estrogen and Androgen Action on Male Sex Behavior and Associated Brain Plasticity

“…Few studies have been able to correlate the behavioral effectiveness of steroid hormones with the concentration of their receptors in a particular brain area (Clark et al, 1985;Balthazart et al, 1996b). Variation in the efficiency of steroid-metabolizing enzymes or in the availability of steroid receptors has also been implicated in some cases (Dessi-Fulgheri et al, 1976;Balthazart et al, 2004). The findings described in this paper indicate that coactivators such as SRC-1 represent another class of proteins that are important for regulating steroid action in adulthood on brain and behavior.…”

Behavioral and physiological correlates of aggressive dominance in male brown lemmings (Lemmus sibiricus)

“…Although plasma T levels have been shown to be related to individual differences in aggressiveness in rhesus monkeys [e.g., Rose et al, 1971;19721, most attempts to find similar correlations in intact rodents have failed [e.g., BUM, 1976;Dessi-Fulgheri et al, 1976;Selmanoff et al, 1977;Sachser and Prove, 19841. One possible reason for this failing may be the pulsatile nature of T secretion in the latter species [Bartke et al, 1973;Mock et al, 19781.…”