Acute injections of corticosterone, norepinephrine and epinephrine retards food passage in the crop of chicks

• Subcutaneous injection of corticosterone inhibits crop emptying rate in chicks.
• Intraperitoneal injection of norepinephrine and epinephrine inhibits crop emptying rate in chicks.
• The injection of alpha- but not beta-adrenergic receptor agonists also inhibits crop emptying.
• These hormones did not affect the number of defecation.
• These hormones inhibit food passage from upper but not lower digestive tract in chicks.

The purpose of the present study was to clarify whether acute injection of stress-related hormones, corticosterone (CORT), norepinephrine (NE) and epinephrine (E) affect food passage in the crop of chicks (Gallus gallus). Subcutaneous (SQ) injection of CORT significantly retarded the food passage in the crop of chicks. Intraperitoneal (IP) injection of NE and E also significantly decreased the crop emptying rate. Additional experiments by using agonists of adrenergic receptors found that IP injection of phenylephrine and clonidine but not isoproterenol retarded the food passage in the crop of chicks. These results demonstrated that the effect of NE and E would be mediated by alpha-1-, alpha-2- rather than beta-adrenergic receptor. Finally, we found that injection of CORT, NE and E had no effect on the number of defecations while intracerebroventricular injection of corticotropin-releasing hormone and urocortin-3 significantly increased it. These results suggest that CORT, NE and E might affect the food passage in the upper digestive tract in chicks.