An experiment in female rats found that chronic naproxen exposure was associated with several changes in ovarian biology, including lower progesterone, weaker catalase activity and altered counts of developing follicles. The authors concluded that exposure to naproxen alone or in combination was associated with ovarian dysfunction, impaired progesterone production and antioxidant status, and disrupted follicle dynamics. Because the work was done in rats, it raises a reproductive-risk question for further study rather than directly answering what the findings mean for people.
Researchers randomly allocated 21 female albino Wistar rats to three equal groups: a control group, a naproxen-only group and a mixture group. Controls received normal drinking water. Exposure lasted 100 days. Naproxen was supplied at 98.39 µg/L in the naproxen-only group and in the mixture. The mixture also contained ibuprofen at 117.14 µg/L, diclofenac at 609.12 µg/L and trifloxystrobin at 0.04 mg/kg/day, with the components reported in a 4:1:3:2 ratio.
How the exposure was tested
The researchers measured ovarian oxidative-stress biomarkers, serum IL-6 and progesterone, follicle counts and Bcl-2 expression in ovarian tissue. Follicles were semiautomatically counted in five to 10 fields per section, ovary and animal by two pathologists who were blinded to group assignment. The methods report five animals per group for follicle quantification, while the overall design reports 21 rats in three equal groups.
Before the experiment, an a priori power analysis indicated seven rats per group under the researchers' assumptions. Group differences were tested with one-way analysis of variance followed by Tukey post hoc comparisons, using a 0.05 threshold for statistical significance.
Several ovarian signals changed
Progesterone was lower in both exposed groups than in controls, with no significant difference between naproxen alone and the mixture. Serum IL-6 did not differ among groups. The reported p-value for the treated-versus-control progesterone comparison was below 0.05, while the mixture-versus-naproxen comparison was 0.68.
An ovarian enzyme called catalase, abbreviated CAT, was also lower in both exposed groups than in controls. The reported p-value was below 0.0001 for each comparison. CAT activity did not differ between naproxen alone and the mixture, with a reported p-value of 0.98. Malondialdehyde, or MDA, did not differ among groups. The authors interpreted the pattern as impaired antioxidant status, although not every oxidative-stress marker changed.
Follicle counts showed a more selective pattern. The mixture group had fewer primary follicles than both controls and the naproxen-only group. Both exposed groups had fewer secondary follicles than controls, but they did not differ from each other on that measure. Primordial follicle counts did not differ. Reported p-values were below 0.001 for mixture versus control primary follicles, 0.01 for mixture versus naproxen, 0.007 for mixture versus control secondary follicles and 0.002 for naproxen versus control secondary follicles.
Bcl-2 staining showed a different pattern depending on the ovarian compartment examined. In antral follicles, expression was lower in both treated groups than in controls, and the reduction was greater in the naproxen-only group than in the mixture group. In stromal cells, the mixture group had the lowest expression, below both the naproxen-only group and controls; naproxen alone was also lower than control. The study did not use complementary direct apoptosis assays, so these staining results do not by themselves demonstrate apoptosis.
Body-weight gain did not differ among groups. The measure called the ovary index was higher in both treated groups than in controls, while naproxen alone and the mixture did not differ on that index. Reported p-values for the ovary index were 0.0016 for naproxen versus control, 0.0011 for mixture versus control and 0.98 between the treated groups.
What the experiment cannot answer
The authors identified two important gaps: additional reproductive hormones were not evaluated, and complementary direct apoptosis assays were not performed. The mixture also contained ibuprofen, diclofenac and trifloxystrobin, so the experiment cannot show which component accounted for each mixture result. Because the study measured ovarian, serum, morphometric and tissue markers in rats, the findings remain evidence of a possible risk in that model rather than a direct measure of human reproductive health. The article is identified as published online ahead of print.
The article reports no relevant potential conflict of interest, while the supplied text does not identify a funding source.
Paper data and sources
Original title: Naproxen at environmentally relevant doses modulates ovarian folliculogenesis: Morphometric analysis and Bcl-2 immunohistochemical expression in Wistar rats after chronic exposure.
Authors: Angham Ouadah, Souheyla Benbia, Yamina Belkhiri et al.
Journal/Repository: Clinical and experimental reproductive medicine
Status: Peer-reviewed
First online: 2026-08-21
DOI: 10.5653/cerm.2026.09215
Original paper · Full text