The brain plays an active role in protecting fertility from heat damage, a study found, uncovering a previously unknown communication system between the nervous system and reproductive cells.
The brain can sense environmental conditions and send molecular signals to the germline—the cells that produce sperm and eggs—helping them withstand stressful conditions such as high temperatures, researchers from the Hebrew University of Jerusalem and Tel Aviv University found.
The discovery challenges the previous understanding that reproductive cells respond directly to heat stress on their own. Instead, the study shows that neurons can prepare and protect reproductive cells before damage occurs, allowing animals to adjust their reproductive responses based on environmental conditions.
The research, led by Dr. Yonatan Tzur of the Hebrew University together with Dr. Chee Kiang Ewe, Dr. Hanna Achache and Professor Oded Rechavi of Tel Aviv University, was published in the peer-reviewed Current Biology.
“For decades, scientists believed that reproductive cells responded directly to environmental conditions such as heat,” the researchers said. “This study demonstrates that neurons actively help prepare and protect the germline by transmitting molecular signals that influence how these cells cope with stressful conditions.”
Using the microscopic worm Caenorhabditis elegans, a common model organism in biological research, the scientists discovered that small RNA molecules produced in neurons help preserve fertility during heat stress.
When this brain-based signaling pathway was disrupted, the worms became largely infertile at elevated temperatures because their sperm failed to develop properly. However, restoring the pathway only in neurons substantially improved fertility, showing that the protective response originates in the nervous system.
“We found that the nervous system isn’t simply reacting to the environment, it actively instructs reproductive cells on how to respond,” said Tzur.
“The brain appears to integrate environmental information and relay it to the germline, helping preserve fertility under stressful conditions. It changes how we think about the relationship between the nervous system and reproduction.”
The researchers also discovered an unexpected role for oxygen-sensing neurons. By changing how the nervous system perceived oxygen levels—without changing the surrounding environment—they were able to improve reproductive success during heat stress.
The finding suggests that animals do not rely on a single environmental signal when deciding whether conditions are suitable for reproduction. Instead, the nervous system may combine information about the environment and help determine whether investing energy in reproduction is likely to result in healthy offspring.
The neuronal signaling pathway also helped protect the genetic integrity of reproductive cells by reducing DNA damage caused by heat stress.
The discovery provides insight into how the nervous system coordinates whole-body responses to environmental challenges and raises the possibility that similar protective mechanisms may exist in other animals, including mammals.
“As climate change increasingly affects fertility across many species, understanding the mechanisms that naturally protect reproductive cells becomes especially important,” said Rechavi. “Our work reveals a completely unexpected communication channel between the brain and the germline that may represent a fundamental biological strategy for adapting reproduction to changing environments.”
The discovery may provide new directions for studying human reproductive health by investigating whether similar mechanisms influence sperm and egg quality under environmental stress.
If similar brain-to-reproductive-cell communication systems exist in livestock, understanding these pathways could help scientists develop strategies to improve animals’ resilience to heat stress and protect fertility as temperatures rise.
