Effects of Age, Egg-laying Activity, and Salmonella-inoculation on the Expressions of Gallinacin mRNA in the Vagina of the Hen Oviduct

Gallinacins (Gal) are antimicrobial peptides that play significant roles in innate immunity in chickens. The aim of this study was to examine whether age of birds and egg-laying activity (laying and non-laying caused by feed-regulation) affect the mRNA expression of Gal-1, -2, and -3 in the vagina of hens, and whether their expressions are changed in response to the stimulation with Salmonella enteritidis (SE) and lipopolysaccharide (LPS). White Leghorn hens were divided into groups of young and old laying hens, and groups of laying and non-laying hens after feed-regulation. Vaginal cells were cultured and stimulated with SE or LPS. Expressions of Gal-1, -2, and -3 mRNA in their vaginal mucosa and cultured cells were examined by quantitative real-time RT-PCR. The expressions of Gal-1, -2, and -3 of the vaginal mucosa were significantly greater in old birds than in young birds. Expression of these Gals in the vagina were decreased in the regressed oviduct of non-laying birds compared with laying birds. The expressions of Gal-1, -2, and -3 in the cultured vaginal cells were increased by stimulation with SE or LPS within 24 h. These results suggest that the mRNA expressions of Gal-1, -2 and -3 in the vagina of laying hens increased with age, whereas they decreased in the regressed oviduct during the non-laying phase. Also, synthesis of these antimicrobial peptides in the vagina may increase in response to SE and LPS to eliminate SE bacteria.