Ghrelin, the Hunger Hormone, Directly Boosts Oxytocin Release

Oxytocin, often called the 'love hormone,' is well-known for its roles in social bonding, reproduction, and stress modulation. However, it also plays a significant part in metabolic regulation, influencing appetite and energy balance. Ghrelin, conversely, is a potent 'hunger hormone' primarily secreted by the stomach, stimulating appetite and promoting fat storage. While both hormones influence metabolism, the direct mechanistic link between ghrelin and oxytocin release has remained largely unexplored.

The study revealed a significant and dose-dependent increase in plasma oxytocin levels following ghrelin administration. The 300 µg/kg ghrelin group exhibited a peak oxytocin concentration of 185 pg/mL at 30 minutes post-injection, which was significantly higher than the 74 pg/mL observed in the saline-treated control group (p<0.001). This represents a remarkable 2.5-fold increase in oxytocin. The lower dose of 100 µg/kg ghrelin also induced a significant rise, peaking at 120 pg/mL at 30 minutes (p<0.01 vs control), a 1.6-fold increase. Oxytocin levels in both ghrelin-treated groups gradually returned to baseline by the 120-minute mark. The most striking finding was that a single intraperitoneal injection of 300 µg/kg ghrelin led to a rapid and significant 2.5-fold elevation in circulating oxytocin levels, reaching 185 pg/mL at 30 minutes post-administration, a 150% increase over saline-treated controls (p<0.001). This suggests a novel neuroendocrine pathway where ghrelin directly influences oxytocin secretion.