Effect of intraperitoneal tryptophan injection on diencephalic CRF and NPY gene expression in acute heat stressed- neonate broiler chicks

High ambient temperature (HT) and heat stress has negative impact on physiological functions. L-tryptophan, serotonergic and kynurenine pathways, has calmative effect during different stress status. This Study was designed to investigate intraperitoneal administration of L-tryptophan (50 mg/kg body weight) during either HT (39 °C) or normal temperature (NT; 31 °C) for 5 hours on cumulative food intake at 1, 2, 3 and 4 hours and diencephalic NPY and CRF gene expression with qPCR method at 5 hours after tryptophan administration. In both two heat stress groups, NPY gene expression significantly was increased in compare with normal temperature groups. Cumulative food intake was increased in heat stress group by tryptophan injection. These results showed that NPY increased to compensate reduced food intake, as anti-stress factor, in heat stress condition and tryptophan maybe involve to improve this effect. Heat stress significantly increased CRH gene expression but tryptophan administration significantly reduced it during heat stress. These results showed, tryptophan modulated Hypothalamus-Hypophysis-Adernal axis by changing in CRH gene expression and tryptophan has buffering effect on stressful states.