Phthalate plasticizer decreases the prion-like protein doppel essential for structural integrity and function of spermatozoa

• Published in: Ecotoxicology and environmental safety 2022-11, Vol.246, p.114159-114159, Article 114159
• Main Authors: Lee, Jae-Hyeon, Park, Seung Hyun, Ryou, Chongsuk, Gye, Myung Chan
• Format: Article
• Language: English
• Subjects: Di-n-butyl phthalate; Mouse; Prnd; Sertoli cells; Spermatozoa; Testis
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2022.114159

Di-n-butyl phthalate (DBP), a well-known endocrine disruptor, causes male reproductive dysfunction. To understand the underlying mechanisms, we performed histological, endocrinological, and biochemical analyses and assessed the expression of genes involved in spermatogenesis and sperm function according to OECD test guideline 407. Following 28 days of administration of the lowest observed adverse effect level dose of DBP to mice, no significant changes in body weight, testis and epididymis weights and histology, serum testosterone level, or testicular daily sperm production were found. Nonetheless, the motility of the epididymal sperm of the DBP group was significantly decreased together with an increase in the incidence of bent tails and abnormal heads. In the testes of the DBP group, lipid peroxidation (LPO) level was significantly increased and testicular Bcl-2 mRNA level was significantly decreased together with an increase in the Bax/Bcl-2 mRNA ratio. In the testes of the DBP group, levels of Prnd mRNA and protein and Pou4f1 mRNA, an activator of the Prnd promotor, were significantly decreased. Of note, prion-like protein doppel (PRND) was significantly decreased together with decreased PRND immunoreactivity in the head, midpiece, and tail of sperm. In the testes of the DBP group, levels of Sox9, Sgp1, and Sgp2 mRNA, which are functional Sertoli cell markers, were significantly decreased. Level of Amh mRNA, a Sertoli cell immaturity marker, was significantly increased together with that of Inha mRNA, suggesting deregulation of the brain-gonadal axis. Together, our findings suggest that DBP at present dosage may potentiate LPO generation and Sertoli cell immaturity via downregulation of Sox9 and disruption of the Pou4f1-Prnd gene network in post-meiotic germ cells without visible changes in spermatogenesis or testosterone level. This may result in structural and functional abnormalities in spermatozoa. Additionally, our findings suggest that assessment of the male reproductive toxicity of phthalate ester plasticizers based on conventional OECD test guidelines should be reconsidered. [Display omitted] ●DBP increased ROS damage in testis and potentiate apoptotic gene network in testis.●DBP deregulated Sox9 and increased Sertoli cell immaturity and inhibin in testis.●DBP at LOAEL dose increased structural abnormalities and impaired sperm motility.●Prion like protein doppel reduction by DBP is coupled with sperm abnormality.●Functional and structural abnor