Long Term Oral Administration of Oregano Essence Effectively Relieves Polycystic Ovarian Rats through Endocrine and Inflammatory Balance

Polycystic ovarian syndrome (PCOS) is alarmingly rising and sustainable therapy/prevention is needed. Here, we evaluated the therapeutic effects of oregano or Origanum vulgare (O. vulgare) essence (OE) on the PCOS rat model system. Vaginal smears monitored the estrous cycle of 40 virgin adult rats, and they received 2 mg estradiol valerate (EV)/0.2 ml corn oil intramuscularly to induce PCOS. At 60 days post-EV injection, all rats were evaluated for follicular development/cysts. The EV-induced PCOS rats were orally administered 250 and 500 mg/kgBW/day of OE for 30 days. OE was also further assessed for its predominant components along with hormonal, histological, and inflammatory-related gene expressions in the ovaries. The main components of the OE were predominantly pulegone (36.3), L-menthone (31.3%), far less piperitone (7.8%), isopiperitone (6.4%), isomenthol (3.6%), humulene epoxide II (2.2%), α-pinene (1.7%), and thymol (1.5%). Hormonal, histological, and inflammatory-related gene expression results showed >4-fold and 1.5-fold increase in FSH and progesterone; ∼50%, 85%, 45%, 55%, and 30% decreased in LH, estradiol, estrogen, testosterone, and AMH; and dose-dependently decreased in mRNA expression of IL-6, IL-1α, NF-kB, TNF-α, and IL-1β by 25–65%, 55–75%, 15–40%, 30–55%, and 35–55%, respectively, and thus decreased the severity of PCOS, boosted endocrine balance, restored functional follicles and corpus luteum, and thus ovulation in PCOS rats. Overall, in the disrupted PCOS rats, OE oral treatment effectively relieved estradiol-induced PCOS rats via: (1) its endocrine balancing on GnRH, FSH, and LH and (2) its anti-inflammatory and antioxidant properties on ovary caused by OE’s useful compounds like pulegone, thymol, and L-menthone. Though many aspects of the effects remain to be tested, such an underlying mechanistic reproductive regulatory effect observed in OE-administered rats further proves its sensible pharmaceutical applications in reproductive medicine and more specifically, PCOS.