Sex boosts brain growth, study suggests

Sex apparently can help the brain grow, according to new findings in rats.

Past findings had shown that stressful, unpleasant events could stifle brain cell growth in adults. To see if pleasant albeit stressful experiences could have the opposite effect, researchers studied the effects of sex in rats.

Scientists played matchmaker by giving adult male rats access to sexually receptive females either once daily for two weeks or just once in two weeks. They also measured blood levels of stress hormones known as glucocorticoids, which researchers suspected might lie behind the detrimental effects that unpleasant experiences have on the brain.

When compared with male virgins, both groups of sexually active rats had cell proliferation, or an increase in the number of neurons, in the hippocampus, a part of the brain linked with memory whose cells are especially sensitive to unpleasant experiences. The rats that had more sex also had adult brain cells grow, as well as a rise in the number of connections between brain cells.

However, the rodents that only saw females once in two weeks had elevated levels of stress hormones, while the rats that had regular access showed no increase in the hormones. Sexually experienced rodents also proved less anxious than virgins, in that they were quicker to chomp down on food in unfamiliar environs.

These findings suggest that while stress hormones can be detrimental to the brain, these effects can be overridden if whatever experiences that triggered them were pleasant.

研究表明：性生活有益大脑成长

性生活似乎有利于大脑发育，这是通过小白鼠实验得出的最新发现。

过去研究表明令人不愉快且有压力的事件会抑制成年人脑细胞的生长。有压力但是令人愉悦的经历会不会带来相反的效果呢？研究人员对小白鼠的性生活进行了研究。

科学家扮起了“红娘”，连续两周制造性成熟的雄性小鼠和雌性小鼠的见面机会，其中一组可以每天见一次，另外一组却是两周只见一次。同时，科学家还测量了肾上腺皮质激素（一种压力激素）水平，他们认为正是该激素导致不愉快经历对大脑造成了不利影响。

与没有发生过性关系的“处男鼠”相比，上述两组性活跃小鼠的细胞有所增殖，有的则是海马体神经元数量的增加。海马体与大脑记忆功能有关，对于不愉快体验非常敏感。性生活较多的小白鼠脑细胞有所生长，而脑细胞之间的连接数目有所增多。

尽管如此，两周只见了一次雌性小鼠的雄性小鼠体内，压力激素水平还是有所升高，另外一组常与雌鼠相见的雄性小鼠则没有变化。“处男鼠”比性生活次数较多的雄小鼠更容易焦虑，而后者在陌生环境中进食反应依旧灵敏。

这些发现表明，压力激素对大脑有不利影响，而只要产生压力激素的经历是令人愉悦的，结果则正好相反。