Abstract

Background:
Polycystic ovary syndrome (PCOS) is associated with anovulation, cystic ovarian morphology, and altered ovarian estrogen signaling. Estradiol benzoate-induced rodent models are useful for reproducing persistent estrus and cystic ovarian morphology, although they do not fully represent the endocrine and metabolic complexity of human PCOS. Gallic acid has antioxidant, anti-inflammatory, and cytoprotective properties that may complement metformin therapy.

Aim:
This study evaluated the adjunctive effect of gallic acid with metformin on ovarian histomorphology, follicular dynamics, and estrogen receptor alpha (ERα) immunoexpression in an estradiol benzoate-induced rat model of PCOSlike ovarian dysfunction.

Methods:
Eighteen female Wistar rats were induced with estradiol benzoate [2 mg/kg body weight (BW), intraperitoneally] for four consecutive days and then randomized into three PCOS-induced groups (n = 6/group): [PCOS control (CP); 1% carboxymethylcellulose sodium], metformin monotherapy (T1; 10 mg/rat/day, approximately 67–77 mg/kg BW/day), and combination therapy (T2; metformin 10 mg/rat/day plus gallic acid 50 mg/kg BW/day). Treatments were administered orally for 14 days. Ovaries were collected for hematoxylin–eosin staining and ERα immunohistochemistry.

Results:
Compared with CP, metformin was associated with improved follicular morphology, and the metformin plus gallic acid group showed the most favorable histological profile. Follicular cyst counts decreased from 2.80 ± 0.54 (CP) to 0.50 ± 0.55 (T1) and 0.16 ± 0.41 (T2). Atretic follicles decreased from 7.50 ± 1.21 (CP) to 5.33 ± 0.20 (T1) and 2.67 ± 0.75 (T2), whereas corpora lutea counts increased from 4.50 ± 0.83 (CP) to 6.33 ± 0.21 (T1) and 11.83 ± 1.45 (T2). ERα-positive area was highest in CP (41.88% ± 4.12%) and was significantly lower in T2 (28.75% ± 2.15%; p

Key words: Estrogen Receptor-α (ERα); Folliculogenesis; Gallic Acid; Metformin; Polycystic Ovary Syndrome (PCOS); Rats.