A Study on SP-A Expression in Rat Testis during Postnatal Development

Abstract Background Surfactant proteins A (SP-A) is integral components of the host defense system, known for their significant antimicrobial properties and diverse immunomodulatory functions, particularly within the lung alveolus. Although SP-A is expressed in the testis, its specific roles in testicular cells, especially in relation to spermatogenesis, remain inadequately characterized. Objective This study addresses the gap by investigating the localization and expression of SP-A in rat testis tissue at 5, 20, 50, and 70 days of postnatal development. Additionally, it examines the localization of SP-A in developing spermatid to spermatozoa within seminiferous tubules. Materials and Methods Wistar albino rats were divided into four groups (N = 6 per group) based on distinct postnatal developmental days (PNDs): 5, 20, 50, and 70. The expression level of SP-A was estimated using Western blotting, and immunohistochemistry analysis was conducted. Results At PND 50, SP-A immunoreactivity was present in elongating spermatids (steps 9–15) and increased at PND 70. Notably, SP-A signals in elongated spermatids (steps 16–19) at PND 50 intensified and peaked at step 16 in early-stage I-II at PND 70 and began to decrease in steps 17–19 in stages IV-XIV at PND 70. Western blot analysis of testis tissue extracts also confirmed the gradual increase in SP-A expression corresponding to postnatal development days. Conclusion These findings suggest that SP-A may serve similar functions in rat testicular tissue as in lung alveoli, including roles in innate immunity, host defense, modulation of the immune response, regulation of inflammation, and protection against infections also may play a role in spermatogenesis and steroidogenesis.