The brain becomes male or female in the embryonic stage. Research in rats shows what happens when the process goes wrong
David Ref
In the early stages of embryonic development, the human brain of males and females is identical in structure. Then the gonads enter the picture: in the case of a male fetus, the hormone testosterone is secreted into the bloodstream and reaches the brain. There it causes (in a way that has not been sufficiently clarified) the process called masculinization - the transformation of the brain into having male characteristics. Indeed, the male brain differs from the female not only in its weight but also in specific areas that are more or less developed.
A study by scientists from the University of Maryland, the results of which were published about six months ago in the journal "Nature Neuroscience", sheds light on the process of forming the gender identity of the brain, and especially on the results of a possible disruption in the process.
The research was done in rats. At the beginning of their article, the researchers point out the advantages of the rat as a model for studying the complex relationship between steroids (which also include gonadal hormones) and the way cells in the brain are organized and sexual behavior in adulthood - a model from which one can also learn about the human brain.
The study dealt with the possible effect of exposure in infancy to non-steroidal anti-inflammatory drugs (NSAID), for example aspirin and indomethacin, on sexual development in rats. The non-steroidal anti-inflammatories inhibit the production of substances called prostaglandins, which cause the sensation of pain in areas of damaged tissue. The study showed that young male rats, who were exposed to non-steroidal anti-inflammatories in the experiment, exhibited defective sexual behavior in their adulthood.
The researchers emphasize again and again, that there is no evidence that this is the case in humans as well. However, obviously
that the research is not only designed to deal with sexual dilemmas of adolescent rats. Its purpose is to deepen the knowledge about the brain's professionalization process, but it clearly shows the need for studies that will examine the effect of the use of aspirin pills on the future development of fetuses.
In rats, the researchers believe, substances from the NSAID group inhibit the creation of a molecule responsible for transmitting the "message" carried by testosterone. This molecule, called PGE2, belongs to the group of prostaglandins. Indeed, as mentioned, its action is inhibited by substances such as aspirin or indomethacin.
In the experiment, doses of indomethacin were injected into young male rats. The behavior of the males was observed upon reaching adulthood, and was compared to the sexual behavior of male rats in a control group, which were injected with an inactive substance when they were young. Females were introduced into the cage of the males: the males treated with indomethacin showed less sexual desire. They displayed poor courtship activity and rarely mated with the females.
The researchers also reported differences in the concentration of synapses - the connections between nerve cells - in the area of the brain associated with sexual activity. In the males who were exposed in their youth to PGE2-inhibiting substances, relatively few connections were found in this area.
In the study, young female rats were exposed to PGE2. These showed male-like behavior in their adulthood and tried to mate with other females in the cage. This provided additional reinforcement to the hypothesis that this molecule participates in the design of the male brain.
The research findings
Young male rats were injected with an anti-inflammatory drug from the group to which aspirin also belongs
In adulthood, these males showed reduced sexual drive, low courtship activity and a low frequency of attempts to mate with females. Compared to normal males, they were diagnosed with a small number of synaptic connections in the area of the brain associated with sexual activity
It seems that a substance responsible for the development of male characteristics of the brain was inhibited by the drug when the males were young, and because of this their sexual development was impaired.
https://www.hayadan.org.il/BuildaGate4/general2/data_card.php?Cat=~~~58121195~~~195&SiteName=hayadan
