In a recent study using mice as models, researchers have discovered that the cerebellum, often known as the ‘little brain’, plays a crucial role in controlling thirst, which is essential for survival. The research team found that a hormone called asprosin travels from the body into the brain to activate Purkinje neurons in the cerebellum. This activation results in an increased urge to search for and consume water.
The cerebellum has intrigued scientists for ages due to its unique structure and complexity, being one of the oldest brain regions in evolutionary terms. While traditionally seen as a center for motor control, recent studies have unveiled its involvement in various non-motor functions such as cognition, emotion, memory, autonomic function, satiety, and meal termination.
The research, published in Nature Neuroscience, involved scientists from University Hospitals (UH), Harrington Discovery Institute at UH, and Case Western Reserve University. Dr. Atul Chopra, the senior author of the study, explained that asprosin is a hormone discovered in 2016, known for stimulating food intake and regulating body weight by activating specific neurons in the hypothalamus, a brain region responsible for hunger signals. The hormone binds to a receptor on the neuron’s surface to execute its functions.
The team’s investigation revealed that besides the hypothalamus, the receptor Ptprd for asprosin is highly expressed in the cerebellum, although the purpose of this was previously unknown.
Dr. Chopra mentioned that their initial assumption about asprosin’s action in the cerebellum coordinating food intake with the hypothalamus was incorrect. A breakthrough occurred when Ila Mishra, a postdoctoral fellow in the lab, found that mice lacking responsiveness to asprosin in the cerebellum exhibited decreased water intake, despite the study primarily focusing on food intake.
These mice displayed decreased activity in Purkinje neurons and reduced feelings of thirst without affecting food intake, motor coordination, or learning. In contrast, mice with inhibited hypothalamic response to asprosin exhibited decreased food intake but maintained normal thirst levels.
Dr. Chopra highlighted the newfound function of cerebellar Purkinje neurons in thirst modulation and emphasized its independent control from their established role in motor control and learning. This discovery opens doors for potential applications in managing thirst disorders like polydipsia, hypodipsia, and adipsia, for which current treatments are limited.
