Obesity-related reproductive issues in men are becoming more prevalent, with growing evidence linking male obesity to reduced testosterone, lower sperm count, and diminished libido. A study published in The Journal of Neuroscience sheds light on how obesity negatively impacts male fertility by affecting brain circuits involved in reproduction and feeding.
The research was conducted using mice fed a high-fat diet to replicate human obesity. The findings revealed that obesity induces chronic changes in brain connections, weakening the communication between brain circuits that regulate both feeding and reproductive functions. This connection may explain why obesity contributes to fertility problems in men.
It has long been established that obesity reduces testosterone levels in men, affecting functions such as muscle mass, cognition, and reproductive health. However, the precise mechanisms through which obesity brings about these changes have remained unclear. The study's aim was to explore how chronic obesity impacts brain circuitry and contributes to low testosterone, reduced sperm count, and poor sperm quality in obese men.
One of the key findings of the study was that obesity significantly altered the brain's reproductive circuits. In obese mice, the frequency of LH pulses—essential for maintaining healthy testosterone levels—was reduced. This led to a drop in testosterone production and decreased sperm count. Interestingly, the reproductive system retained its ability to function normally when directly stimulated, indicating that obesity primarily disrupts the brain's regulatory control over reproductive functions.
The study also identified a specific area of the brain impacted by obesity—kisspeptin neurons. These neurons are crucial for triggering the release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH), which are vital for maintaining healthy testosterone levels and sperm production. Chronic obesity suppresses the activity of these neurons, which may explain the link between obesity and reproductive issues.
Djurdjica Coss, the study's corresponding author and a professor of biomedical sciences at the University of California, Riverside School of Medicine, emphasized the broader significance of these findings. "A long-term goal of my research is to identify the molecular and cellular mechanisms that regulate reproductive function, which is necessary for the survival of the species," Coss said.
She added that the research is particularly relevant to individuals facing unexplained infertility, as 1 in 8 couples experience infertility. This issue also affects endangered species and agricultural animals, where infertility is becoming more common due to modern farming practices. Coss's research could pave the way for new treatments and strategies to address rising infertility rates in both humans and animals.