A new study
suggests estrogen may serve an important function in the brain, one
that even encourages violence… at least, in mice.
Estrogen-producing nerve cells, UC San Francisco researchers discovered, exert specific effects on aggressive behavior in both male and female mice.
“Though social behaviors marking of territory, recognizing potential mates, successfully mating, fighting seem quite ‘seamless’ when we observe them, this study shows that different neural systems control quite distinct, specific components of these behaviors,” Dr. Nirao Shah, senior author of the study, stated in a press release.
Working with adult mice, Shah and a team of researchers depleted estrogen-producing nerve cells — also known as aromatase-expressing (aromatase+) cells — in a brain region known as the posterodorsal medial amygdala, or MeApd.
This structure, in which aromatase+ cells make up 40 percent of the total neurons, is vital to social and reproductive behavior. In fact, it is linked to the olfactory bulb in the forebrain where it receives smell and pheromonal information commonly used by mice to identify other mice and to respond appropriately.
Using a genetic technique, the researchers eliminated the small cluster of aromatase+ cells from the MeApd in males, then in females. At first, the genetically modified male mice behaved as they normally do:
They marked their territory, and they recognized, courted, and successfully mated with females. However, when these mice encountered an unfamiliar male in their territory, they showed a dramatically altered social style.
Typically, male mice rattle their tails and then attack a same-sex intruder. The mice without aromatase+ neurons, though, showed less tail-rattling, and then it took them longer to mount an attack.
In fact, the researchers saw a direct relation between the number of aromatase+ cells that had been eliminated and the lag time before an attack.
Strangely, when these genetically modified mice finally did attack, the aggressiveness of their fighting resembled that of normal males.
In females, the consequences of depleted aromatase+ cells only played out after they’d given birth. The genetically modified females responded to male mice in all the usual ways, but then, strangely, they seemed to lack the normal level of maternal aggression.
Generally, female mice with nursing pups will attack unfamiliar male mice, which are known to kill rival males' pups CONTINUE READING
MEDICALDAILY
Estrogen-producing nerve cells, UC San Francisco researchers discovered, exert specific effects on aggressive behavior in both male and female mice.
“Though social behaviors marking of territory, recognizing potential mates, successfully mating, fighting seem quite ‘seamless’ when we observe them, this study shows that different neural systems control quite distinct, specific components of these behaviors,” Dr. Nirao Shah, senior author of the study, stated in a press release.
Working with adult mice, Shah and a team of researchers depleted estrogen-producing nerve cells — also known as aromatase-expressing (aromatase+) cells — in a brain region known as the posterodorsal medial amygdala, or MeApd.
This structure, in which aromatase+ cells make up 40 percent of the total neurons, is vital to social and reproductive behavior. In fact, it is linked to the olfactory bulb in the forebrain where it receives smell and pheromonal information commonly used by mice to identify other mice and to respond appropriately.
Using a genetic technique, the researchers eliminated the small cluster of aromatase+ cells from the MeApd in males, then in females. At first, the genetically modified male mice behaved as they normally do:
They marked their territory, and they recognized, courted, and successfully mated with females. However, when these mice encountered an unfamiliar male in their territory, they showed a dramatically altered social style.
Typically, male mice rattle their tails and then attack a same-sex intruder. The mice without aromatase+ neurons, though, showed less tail-rattling, and then it took them longer to mount an attack.
In fact, the researchers saw a direct relation between the number of aromatase+ cells that had been eliminated and the lag time before an attack.
Strangely, when these genetically modified mice finally did attack, the aggressiveness of their fighting resembled that of normal males.
In females, the consequences of depleted aromatase+ cells only played out after they’d given birth. The genetically modified females responded to male mice in all the usual ways, but then, strangely, they seemed to lack the normal level of maternal aggression.
Generally, female mice with nursing pups will attack unfamiliar male mice, which are known to kill rival males' pups CONTINUE READING
MEDICALDAILY
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