Neurosecretory protein GL stimulates feeding behavior and fat accumulation in Japanese quails (Coturnix japonica)

Neurosecretory protein GL (NPGL) is a novel hypothalamic neuropeptide that promotes fat accumulation in rats, mice, and neonatal chicks. However, its role in Japanese quail (Coturnix japonica) remains unclear. In this study, we investigated the effects of chronic intracerebroventricular infusion of NPGL on body mass, food intake, and fat deposition in five-week-old male Japanese quails. A 13-day infusion of NPGL significantly increased body mass, food intake, and the masses of subcutaneous fat, abdominal fat, and liver. In contrast, water intake and the masses of the pancreas, testes, heart, and muscle remained unchanged. Blood concentrations of triglyceride, glucose, and non-esterified fatty acid were unaffected. Real-time qPCR analysis revealed a significant upregulation of NPGM, a paralogous gene of NPGL, in the hypothalamus. Additionally, the expression of stearoyl-CoA desaturase 1 (SCD1), a key enzyme involved in lipogenesis, showed an increasing trend in the liver. Although the fatty acid ratio used as the SCD1 activity index (palmitoleate/palmitate) did not change, the de novo lipogenesis index (palmitate/linoleate) tended to increase in both the liver and abdominal fat. These results suggest that NPGL promotes fat accumulation in Japanese quails, indicating its potential involvement in avian adiposity.