Abstract
In the mammary glands, production of antimicrobial components and formation of less-permeable tight junctions (TJs) are important for safe milk production. Previously, we reported that local heat treatment of udders using disposable heating pad enhances the components of innate immunity in lactating goat mammary glands. Gingerol is a polyphenol present in ginger that can induce heat-like effects. However, oral administration of polyphenols causes a decrease in biological activity through conjugation and metabolic conversion. Here, we investigated the effects of gingerol on antimicrobial components and TJs by topically applying it to lactating goat udders. Gingerol application increased the somatic cell count, cathelicidin-2 concentration, and proportion of polymorphonuclear cells in the milk and interleukin-8 production. Moreover, gingerol treatment enhanced β-defensin-1 production in milk, cultured mammary epithelial cells, and cultured somatic cells. Contrastingly, gingerol treatment did not affect the concentrations of blood-derived components (Na+, albumin, and IgG) in the milk or the TJ barrier function of cultured mammary epithelial cells. These findings suggest that the topical application of gingerol, similar to local heat treatment, to udders enhances the components of innate immunity in mammary glands. These findings may be useful for the prevention of mastitis in milk-producing animals and, hence, safe and stable dairy production.