A team of researchers from the University of Aveiro and the University of
Porto, both in Portugal, and the University of Birmingham in the U.K. has
found that for humans, the brain and testis have the highest number of
common proteins. In their paper published in the journal Royal Society Open
Biology, the group describes their study of protein similarities between
tissues.
In this new effort, the researchers noted that evidence from other studies
has found some signs of similarities between testis and the human brain.
Intrigued, they initiated a study that involved analyzing the proteins
produced by different parts of the body and then comparing them to see
similarities.
The researchers found the greatest similarities between the
brain and testicles—13,442 of them. This finding suggests that the brain and
the testicles share the highest number of genes of any organs in the body.
The team next focused on the shared proteins and found that most of them
were involved in the development of tissue and communications. They suggest
this finding was not surprising, considering that proteins from both organs
consume high amounts of fuel—one to process thinking, the other to produce
millions of sperm every day.
They also note that testis and nerve cells are
both involved in moving material created inside of them to an outside
environment—sperm cells move fertilization factors and neurons move
neurotransmitters. Both are part of processes known as exocytosis.
Additionally, as part of exocytosis, sperm allow parts of themselves to fuse
with an egg. With neurons, exocytosis involves creating neurites that allow
for communication between cells.
The researchers also took a step back from their work, noting that there may
be a reason for the similarities between the proteins produced by the two
organs. They note, for example, that prior research efforts have shown a
link between brain disorders and sexual dysfunction. And some have even
found a link between the quality of sperm produced and intelligence. They
suggest more research is required to better understand the connections
between the two organs, if there are any.
Reference:
Bárbara Matos et al, Brain and testis: more alike than previously thought?,
Open Biology (2021). DOI:
10.1098/rsob.200322