The study by Princeton scientists was conducted to see if pleasant but stressful experiences could have an opposite effect, Live Science reported.
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.
A comparison with male virgins showed both groups of sexually active rats had cell proliferation, or an increase in the number of neurons, in the hippocampus.
The hippocampus is a part of the brain linked with memory whose cells are especially sensitive to unpleasant experiences.
The study found that the more sex the rats had the more their adult brain cells grew, and there was also as a rise in the number of connections between brain cells.
But where the rodents that only saw females once in two weeks were concerned, they had elevated levels of stress hormones, which was absent from rats that had regular access.
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 triggered them were pleasant.
The scientists have published their findings online in the journal PLoS ONE.