Hailed as the most complex structure in the universe, the human brain is without equal, but which organ comes closest? The testicle, according to a study.
The human body is a collection of different organs contributing together to maintain overall health and homeostasis. At the top of this machinery is the human brain, the control center of the nervous system. It receives signals from sensory organs which it translates into functional information to multiple physiological compartments. The brain is also responsible for speech production, memory storage, and the development of thought and emotion.
The human testicle plays a leading role in the reproduction and evolution of our species. It is he who produces gametes (sperm) and which synthesizes/secretes male hormones, mainly testosterone.
The brain and testicles are not that different
These two structures therefore seem to perform functions which, on paper, are separable. Despite everything, it has become apparent in recent decades that the human brain and testicles shared several characteristics.
We know, for example, that of all the organs in the body, these two structures share the greatest number of genes. Recently, a study also highlighted a positive correlation between general intelligence and sperm quality. A possible association between male sexual dysfunction and neurological disorders has also been proposed.
But those aren’t the only similarities. While the brain is made up of neurons supported by glial cells, the testes also contain supporting cells called Sertoli cells. Interestingly, both of these cell types produce lactatea substance used as an energy source by neurons and germ cells.
The brain and testicles are also distinguished by their very high energy requirements, and are in fact particularly sensitive to oxidative stress. To counter this weakness, both fabrics have developed similar protective barriers : the blood-brain barrier and the blood-testicular barrier.
A large number of common proteins
More recently, researchers from the University of Aveiro and the University of Porto, Portugal, and the University of Birmingham, UK, discovered that the human brain (both male and female) and testicles contain the greatest number of common proteins.
In their article published in the journal Royal Society Open Biology, the researchers explain having compared the proteomes (all of the proteins expressed in a cell) of thirty-three different types of human tissues. These were taken from the brain, heart, ovaries, testicles, liver, prostate, cervix and kidneys.
According to these results, the brain is composed of 14,315 different proteins, while the testicles contain 15,687. In these samples, the two types of tissue share proteins. 13,442 in common.
These similarities between human brain and testicles are not fully understood, but researchers suggest that they may be the product of a process called speciation. According to this theory, the same natural selection pressures that led to the emergence of our species could have helped shape the development of the brain and testes, cementing the relationship between these two tissues.
Although their primary functions differ, studying the similarities between the brain and testes highlights the importance of cellular communication and regulatory processes in these two organs. Researchers believe that common proteins could support the smooth running of complex processes, such as hormone production and the transmission of neuronal information. These results highlight how seemingly dissimilar structures can share fundamental mechanisms for survival and reproduction, illustrating a fascinating functional convergence within the human body.
