Menu

Fast-Tracking Sexual Maturation

The brains and bodies of young female rats can be accelerated into puberty by the presence of an older male or by stimulation of the genitals.

Nov 1, 2017
Ruth Williams

ACCELERATED DEVELOPMENT: In prepubescent 21-day-old female rats, the genital cortex region (black) of the somatosensory cortex exhibits accelerated growth when the young female is exposed to touch and contact with a sexually mature male (right, center panel). After nine days of exposure, the genital cortex of the young rat is the same size as that of a fully mature sexual female. PLOS BIOLOGY, 15:e2001283, 2017Contrary to the longstanding belief that puberty is largely controlled by hormones, new evidence shows that sexual touch is a powerful puberty promoter. Touching prepubescent female rats’ genitals can cause the brain region that responds to such tactile stimuli to double in size and their bodies to show signs of puberty up to three weeks earlier than nonstimulated females, according to a report in PLOS Biology on September 21. The study reveals the hitherto unappreciated influence of physical sexual experience on the young brain and body.

“The dominant idea has been that puberty is controlled in the brain and in behavior by the release of hormones . . . but there has been a smattering of findings over the years that additional environmental influences effect puberty and the onset of sexual behavior,” says Dan Feldman of the University of California, Berkeley, who was not involved in the study. This new work “suggests that maybe this is true and that actual tactile stimulation can be something that accelerates the onset of puberty,” he adds.

Puberty in mammals is a period of dramatic changes not just to the body, but to behavior and brain function. Indeed, one of the most pronounced changes, recently observed in both male and female rats, is the doubling in size of the genital cortex, which is a part of the larger somatosensory cortex—the brain area associated with physical sensation.

But these brain, behavior, and body changes are not simply an age-dependent process. Mammalian puberty can also be under strong social control. In an earlier study, exposure to male pheromones and physical interaction with males was shown to accelerate puberty in young female mice, for example.

Michael Brecht, a neuroscientist at the Bernstein Center for Computational Neuroscience in Berlin, who with colleagues had previously reported the puberty-associated expansion of the rat genital cortex, wondered whether this dramatic brain change might occur in response to physical interactions, and if so, whether it might be linked to the male-induced accelerated puberty found in female mice.

To find out, he and his team housed prepubescent female rats (21 days old) either with an older male rat or in a cage where an older male could be seen, heard, and smelled, but not touched. These conditions were designed to distinguish the effects of direct tactile stimulation from exposure to pheromones only.

They found that after co-housing the females with a male for one week, the now 30-day-old females had genital cortices the size of fully sexually mature females (50 days old), while those females not in contact with the male had only mid-sized cortices. Co-housing with a male also accelerated the physical signs of puberty in the females—namely, an increased uterine weight and vaginal opening—compared with those in the noncontact cages.

To figure out just what it is about physical contact that might accelerate puberty, the team examined whether touch alone, without a male, could recapitulate the effects. Stroking the young female rats’ genitals with a small brush held by one of the researchers produced similarly accelerated genital cortex expansions and physical signs of puberty.

The team went on to show that inhibiting the activity of neurons in the genital cortex using a locally applied neurotoxin prevented both neurological and physical signs of puberty in young female mice co-housed with older males. The authors interpret this result to mean that neural activity in the genital cortex may not only expand in response to a sexual stimulus, but be necessary for puberty to progress.

These first sexual experiences, I think, change the brain in a very profound way that we are only beginning to understand.—Michael Brecht, Bernstein Center
 for Computational Neuroscience in Berlin

“I think [our work] puts more emphasis on sexual touch as a regulator of brain development and of puberty,” says Brecht. “These first sexual experiences, I think, change the brain in a very profound way that we are only beginning to understand,” he adds. That said, Brecht’s team found that sex hormones were still essential for genital cortex expansion in puberty.

“It’s a potentially important paper,” says Barry Komisaruk, a psychologist at Rutgers University, “because it’s showing that sensory stimulation and hormonal activity can influence the structure and function of the brain.”

This new work “provides insight into the possible mechanisms underlying the widely observed, but poorly understood, phenomenon of puberty occurring about a year earlier in girls who have been sexually abused,” says psychiatrist Jay Giedd of the University of California, San Diego. The caveat, of course, is that these studies were in rats and such experiments would obviously be impossible to conduct in humans. Nevertheless, Giedd adds, “it would be really amazing if this mechanism only occurred in rats.” (C. Lenschow et al., “Development of rat female genital cortex and control of female puberty by sexual touch,” PLOS Biol, 15:e2001283, 2017.) 

A version of this story was published at the-scientist.com on September 21, 2017.

September 2018

The Muscle Issue

The dynamic tissue reveals its secrets

Marketplace

Sponsored Product Updates

StemExpress LeukopakâNow Available in Frozen Format

StemExpress LeukopakâNow Available in Frozen Format

StemExpress, a Folsom, California based leading supplier of human biospecimens, announces the release of frozen Peripheral Blood Leukopaks. Leukopaks provide an enriched source of peripheral blood mononuclear cells (PBMCs) with low granulocyte and red blood cells that can be used in a variety of downstream cell-based applications.

New Antifade Mounting Media from Vector Laboratories Enhances Immunofluorescence Applications

New Antifade Mounting Media from Vector Laboratories Enhances Immunofluorescence Applications

Vector Laboratories, a leader in the development and manufacture of labeling and detection reagents for biomedical research, introduces VECTASHIELD® Vibrance™ – antifade mounting media that delivers significant improvements to the immunofluorescence workflow.

Best Practices for Sample Preparation and Lipid Extraction from Various Samples

Best Practices for Sample Preparation and Lipid Extraction from Various Samples

Download this white paper from Bertin Technologies to learn how to extract and analyze lipid samples from various models!

Bio-Rad Launches CHT Ceramic Hydroxyapatite XT Media and Nuvia HP-Q Resin for Process Protein Purification

Bio-Rad Launches CHT Ceramic Hydroxyapatite XT Media and Nuvia HP-Q Resin for Process Protein Purification

Bio-Rad Laboratories, Inc. (NYSE: BIO and BIOb), a global leader of life science research and clinical diagnostic products, today announced the launch of two new chromatography media for process protein purification: CHT Ceramic Hydroxyapatite XT Media and Nuvia HP-Q Resin.