Strangely, the brain and the testes share a series of commonalities that make them perhaps the most biochemically similar organs in the human body.
A series of studies have already highlighted similarities between the brain and the testes, and their understanding and implications have become of real interest to scientists. Thus, an association has been suggested between the degree of intelligence and the quality of sperm, while a relationship has been reported between certain mental and testicular disorders.
A Portuguese team (Universidade de Aveiro) explored the issue down to the molecular level. By comparing molecular functionality, the researchers were able to show that brain and testicular tissues share many commonalities, in particular the production of a large number of identical proteins. Most of them are involved in tissue development and communication. Both organs also consume a great deal of energy, one for cognitive functions, the other for producing millions of sperm every day.
The authors also stress the importance of the exocytosis process for both the brain and the testes, that is to say the mechanism by which a cell expels molecules or particles via its membrane. On one hand, this ensures communication between brain cells, namely the expulsion of neurotransmitters from neurons. On the other hand, it allows reproduction by moving genetic material from the testes into the egg. The researchers also point to similar molecular receptors and very similar signaling pathways, all of this in very close connection with proteins closely linked to genes, which are also largely similar.
As to why the brain and testes share so many biochemical characteristics, the authors have no clear answer. They refer in part to the process of speciation (by which humans evolved and distinguished themselves from other species from common ancestors), but above all they call for even more in-depth study. These will contribute to a better understanding of dysfunctions affecting the brain and testes, with the involvement of similar proteins, and to the development of therapeutic strategies.