Cyclooxygenase 2 (COX2) expression and prostaglandin synthesis in neonatal rat testicular germ cells: Effects of acetaminophen and ibuprofen

Abstract

Background: In infants, fever is often treated with acetaminophen or ibuprofen, two antipyretic and analgesic drugs inhibiting cyclooxygenases (COXs), enzymes catalyzing prostaglandin production. Infancy represents a critical developmental period when neonatal germ cells/gonocytes differentiate to spermatogonial stem cells required for spermatogenesis.

Objectives: (a) Determine the expression of Cox2 and associated genes in postnatal day (PND)3 rat gonocytes compared to spermatogonia. (b) Examine whether acetaminophen or ibuprofen disrupts neonatal gonocyte functions. (c) Determine whether neonatal gonocytes produce prostaglandins and whether this process is altered by acetaminophen and ibuprofen.

Materials and methods: The expression of Cox2 and related genes was determined by gene arrays and qPCR. Cox2 protein levels were determined by immunocyto/histochemistry and immunoblots. The effects of acetaminophen and ibuprofen on PND3 gonocyte viability, apoptosis, proliferation, and differentiation were examined alone and with a proliferation cocktail or differentiation factor. Prostaglandins were examined by immunocyto/histochemistry and LC-MS.

Results: Cox2 and related genes are highly expressed in gonocytes and spermatogonia. Acetaminophen and ibuprofen did not affect gonocyte survival or apoptosis, but they increased gonocyte proliferation. Ibuprofen significantly reduced RA-induced Stra8 expression, indicating an inhibitory effect on differentiation. Ibuprofen combined with RA decreased Cox2 mRNA and protein expression. PGE2 and PGF2α were produced by neonatal gonocytes and decreased by acetaminophen and ibuprofen.

Discussion: The concomitant decrease of Stra8 expression, Cox2 expression, and PGE2 and PGF2a production in gonocytes co-treated with RA suggests that Cox2 plays a role in PND3 gonocyte differentiation. The effects of acetaminophen and ibuprofen on proliferation suggest a negative relationship between Cox2 and proliferation. Treating neonates with acetaminophen or ibuprofen could disrupt gonocyte development, leading to adverse reproductive effects.

Conclusion: Understanding COX2 role in neonatal gonocytes and the potential risk of acetaminophen and ibuprofen treatment of infants may help prevent male reproductive pathologies.

Keywords: COX2; acetaminophen; differentiation; gonocytes; ibuprofen; neonatal germ cells; proliferation; prostaglandins.