Ghrelin, a hormone that stimulates growth hormone secretion and signals energy insufficiency, interacts with the growth hormone secretagogue receptor (GHSR). This study systematically examined the distribution of GHSR mRNA in the adult rat and mouse brains and cervical spinal cords using in situ hybridization histochemistry (ISHH) with novel cRNA probes specific for the functional GHSR (type 1a variant). GHSR mRNA was found in several hypothalamic nuclei, including the arcuate nucleus (Arc), ventromedial nucleus (VMH), and lateral mamillary nuclei, as well as in other regions such as the dorsal vagal complex, which includes the area postrema, nucleus of the solitary tract, and dorsal motor nucleus of the vagus. GHSR was also detected in parasympathetic preganglionic neurons and in the substantia nigra and ventral tegmental area, where it co-existed with tyrosine hydroxylase (TH) and cholecystokinin (CCK). The study confirmed GHSR expression in various brain regions, including the hippocampus, septum, and midbrain, and highlighted the importance of GHSR in regulating body weight homeostasis and energy balance. The findings suggest that GHSR is expressed in a wide range of brain regions, including those involved in autonomic function, reward behaviors, and locomotor activity. The study also compared the distribution of GHSR in rats and mice, noting some differences in signal density and expression patterns. Overall, the results provide a comprehensive map of GHSR expression in the brain, highlighting its role in various physiological processes.Ghrelin, a hormone that stimulates growth hormone secretion and signals energy insufficiency, interacts with the growth hormone secretagogue receptor (GHSR). This study systematically examined the distribution of GHSR mRNA in the adult rat and mouse brains and cervical spinal cords using in situ hybridization histochemistry (ISHH) with novel cRNA probes specific for the functional GHSR (type 1a variant). GHSR mRNA was found in several hypothalamic nuclei, including the arcuate nucleus (Arc), ventromedial nucleus (VMH), and lateral mamillary nuclei, as well as in other regions such as the dorsal vagal complex, which includes the area postrema, nucleus of the solitary tract, and dorsal motor nucleus of the vagus. GHSR was also detected in parasympathetic preganglionic neurons and in the substantia nigra and ventral tegmental area, where it co-existed with tyrosine hydroxylase (TH) and cholecystokinin (CCK). The study confirmed GHSR expression in various brain regions, including the hippocampus, septum, and midbrain, and highlighted the importance of GHSR in regulating body weight homeostasis and energy balance. The findings suggest that GHSR is expressed in a wide range of brain regions, including those involved in autonomic function, reward behaviors, and locomotor activity. The study also compared the distribution of GHSR in rats and mice, noting some differences in signal density and expression patterns. Overall, the results provide a comprehensive map of GHSR expression in the brain, highlighting its role in various physiological processes.