Influence of peripheral lipopolysaccharide (LPS) on feed intake, body temperature and hypothalamic expression of neuropeptides involved in appetite regulation in broilers and layer chicks

ABSTRACT

1. This study examined the expression of genes related to appetite-regulating neuropeptides in the hypothalamus of broiler and layer chicks (Gallus gallus) after intraperitoneal (IP) injection of lipopolysaccharide (LPS).

2. Both broiler and layer chicks received (n = 10 per group) LPS at doses of 0 and 200 µg and feed intake was measured up to 6 h after injection. In a further experiment, (n = 8 per group) mRNA abundance of some hypothalamic neuropeptides was measured 2 h after injection. The rectal temperature of each chick was measured before and 2 h post-injection.

3. Feed intake was significantly decreased by LPS from 2 h after injection and thereafter, while the rectal temperature did not change.

4. LPS decreased the expression of appetite-enhancing neuropeptides: neuropeptide Y (NPY) and agouti-related peptide (AgRP) in broilers and, NPY in layer chicks. The expression of appetite-suppressing neuropeptides (corticotrophin-releasing factor (CRF), proopiomelanocortin (POMC) and, cocaine and amphetamine regulated-transcript (CART) was not changed in broilers, while CRF tended to decrease and POMC was significantly decreased in layers. The abundance of the cytokine tumour necrosis factor-alpha (TNF-α) did not change in broilers but was decreased in layers.

5. The findings indicated that the reduction in gene expression of hypothalamic appetite-enhancing neuropeptides NPY and AgRP is responsible for anorexia caused by LPS at a dose that did not influence body temperature.

KEYWORDS:

• Gene expression
• lipopolysaccharide
• anorexia
• hypothalamus
• appetite-regulating neuropeptides
• broilers
• layers

Acknowledgments

This work was conducted using a grant by the research vice presidency of Shahid Bahonar University of Kerman, Kerman, Iran.

Disclosure statement

The authors declare no conflict of interest.

Animal welfare statement

The authors confirm that the ethical policies of the journal, as noted on the journal’s author guidelines page, have been adhered to and the appropriate ethical review committee approval has been received. The authors confirm that they have followed EU standards for the protection of animals used for scientific purposes.