Sericin-induced hypophagia mediates via M1 muscarinic, NMDA glutamate and glycine receptors in neonatal chicken

The objective of this study was to ascertain the interaction between muscarinic, NMDA glutamate, and glycine receptors on sericin-induced hypophagia in neonatal chickens. This study comprised six experiments, with four groups in each and 11 repeats per group. In Experiment 1, the chicken received an ICV injection of saline, sericin (0.5 nmol), or Telenzepine (an M1 muscarinic receptor antagonist, 125 nmol). Group 4 received a co-injection of sericin and Telenzepine. In experiments 2-6, the chicken received ICV injections of AF-DX116 (an M2 muscarinic receptor antagonist, 125 nmol), 4-DAMP (an M3 muscarinic receptor antagonist, 125 nmol), PD102807 (an M4 muscarinic receptor antagonist, 125 nmol), MK-801 (an NMDA glutamate receptor antagonist, 15 nmol), and strychnine (a glycine receptor antagonist, 100 nmol) instead of Telenzepine. Subsequently, the cumulative food intake was quantified at 30, 60, and 120 minutes post-injection. The results demonstrated that the ICV injection of sericin (0.5 nmol) led to a notable reduction in cumulative food intake when compared to the control group (P<0.05). The co-injection of telenzepine and sericin resulted in a notable reduction in the hypophagia induced by sericin, as evidenced by a statistically significant difference (P<0.05). The co-injection of MK-801 and sericin resulted in a reduction of the hypophagic effects of sericin when compared to the control group (P<0.05). The co-injection of strychnine and sericin resulted in a notable reduction in the hypophagic effects of sericin, as evidenced by a statistically significant difference when compared to the control group (P<0.05). These findings suggest that sericin-induced hypophagia is mediated via M1 muscarinic, NMDA glutamate, and glycine receptors in neonatal chickens.