EJMS

Abstract

Background and objective: breast feeding continues to have practical and psychologic advantages. Therefore, breast feeding should be considered a public health issue and not only a lifestyle choice. Heat stress, especially in tropical and subtropical areas, induces serious physiological disturbances and damage of various body organs including the mammary glands during lactation. The mechanism of heat stress-induced effects on the lactating mammary glands remains unclear. Therefore, the present study was performed to investigate these effects and to demonstrate the possible underlying mechanism. Material and Methods: Twenty four pregnant female Wistar rats were allocated into two groups; control group and heat stress-exposed group, each of twelve rats. Animals of heat stress-exposed group were exposed to heat stress for two hours daily for 10 days of lactation. At the end of the experiment, all animals were sacrificed on day 10 post-partum under general anesthesia and the right fourth mammary glands were dissected out, excised and processed for histopathological and immunohistochemical studies. Results: The mammary glands from rats that were exposed to heat stress showed collapse of alveoli, apoptotic bodies in the lining epithelial cells of alveoli and ducts and mononuclear inflammatory cell infiltrate in the stroma. Also, heat stress induced activation of NF-kB/p65 in the lining epithelial cells of alveoli and ducts of these glands. Conclusion: It may be concluded that heat exposure-induced stress caused involution of the lactating mammary glands of female adult rats as indicated by collapse of secretory structures through activation of NF-kB/p65 signaling pathway. Therefore, monitoring of NF-kB/p65 activation could be considered as a new therapeutic strategy to ameliorate or prevent involution of lactating mammary glands in rats exposed to heat stress.