The present study demonstrated that LTZ-induced PCOS rats exhibit the clinical and biochemical characterizations of women with PCOS. In line with previous observations, our results showed that PCOS-like conditions in rats including an abnormal estrus cyclicity, elevated body weight, insulin resistance, total cholesterol, triglycerides, LDL-C, MDA, LH, FSH, and testosterone levels [32]. The animals also had lower HDL-C, estrogen, progesterone, SOD, and GSH-Px levels than the normal control group. We demonstrated, for the first time, treatment with F. deltoidea at 500 and 1000 mg/kg/day can ameliorate PCOS symptoms in rats by improving insulin resistance, antioxidant activity, and hormonal balance. We also showed that F. deltoidea significantly decreases the number of cystic follicles, increases the number of corpus luteum, and normalizes the endometrium thickness.
Treatment with LTZ to adult rats for 21 days increased body weight, BMI, Lee’s index (Table 1), and resulted in disruption of the estrous cycle (Fig. 1). Lee’s index values of the PC group were higher than 310 throughout the experimental period, indicating the efficacy of LTZ in the induction of PCOS. A significant increase between the initial and final measurement of BMI further confirms the overweight and obesity incidence in PCOS rats. Similar findings have been reported in different animal models of PCOS [33–35]. It is important to note that F. deltoidea treatment at 500 and 1000 mg/kg/day for up to 15 days significantly reduced BMI and Lee’s Index values in PCOS rats. A small weight loss of approximately 5% can improve insulin resistance, hormone levels, menstrual cycles, and infertility associated with PCOS [36, 37]. Indeed, lower HOMA-IR values were found in the PFD500 and PFD1000 groups (Table 2), suggesting the insulin-sensitizing activity of F. deltoidea. Animals in these groups were also associated with improvement in estrous cyclicity during the treatment phase. These findings were consistent with the notion that insulin sensitiser may improve menstrual cyclicity and ovulation in PCOS [38].
We demonstrated that F. deltoidea treatment at 500 and 1000 mg/kg/day significantly reduced the concentrations of testosterone, FSH, and LH as well as increased estrogen and progesterone to near-normal levels in PCOS rats (Table 4). These results imply that F. deltoidea exhibited anti-androgenic and estrogenic properties in PCOS rats that in turn can explain the suppression of FSH and LH. A similar finding has been reported by Nur Ajeerah et al. [15]. Supporting this view, the presence of catechin, gallocatechin, and epigallocatechin have been reported by Haida et al. [39]. Catechin is known to suppress appetite, reduce food consumption, and is responsible for the reduction in testosterone level [40, 41]. Meanwhile, epigallocatechin and apigenin were proven to inhibit 17β-HSD, 3β-HSD enzymes, and P450 activity that lead to inhibitory effects on testosterone production. However, Rocha et al. [42] demonstrated that normalization of testosterone levels did not improve BMI, glucose, or lipid metabolism in postmenopausal hyperandrogenism rats. It should be mentioned that the effects of serum androgen normalization are different in reproductive and non-reproductive status. It has also been shown that therapy aimed at reducing androgen over-production failed to ameliorate insulin resistance in PCOS [43]. Further analyses are, therefore, needed to assess the biological outcomes following F. deltoidea.
Lipid disturbances are the most common metabolic abnormality in PCOS. Our current results showed that the administration of LTZ for 21 days was not only able to develop PCOS symptoms similar to those occurring in humans but also affect the serum lipid profiles (Table 4). A similar finding has been reported by Ndeingang et al. [44]. Nevertheless, Wasan et al. [45] provide evidence that LTZ did not significantly alter serum lipid profile. This discrepancy can be justified by the fact that LTZ only has a good short-term tolerability profile [46]. Continuous exposure to LTZ has been demonstrated to cause significant changes in lipid profile [47]. Strikingly, F. deltoidea restored the levels of total cholesterol, triglycerides, LDL-C, and HDL-C to normal levels in PCOS rats that had improvement in hormonal profile and the estrous cycle. The data support that the relationship between lipid profile and sex hormones [48, 49]. These results are also compatible with earlier studies demonstrating that F. deltoidea can reverse the abnormalities in the lipid profile of diabetic rats [50] and adults with pre-diabetes [51].
Lipid peroxidation and antioxidants were further evaluated to understand the potential of F. deltoidea in treating PCOS. We found that the PCOS rats had higher serum MDA and lower endogenous antioxidant enzymes (SOD and GSH-Px) levels than normal control (Table 5), indicating oxidant-antioxidant imbalance occurred. A disturbance in the antioxidant-prooxidant balance has been reported to induce pathological consequences in oocyte maturation, ovulation, fertilization, implantation, and embryo development [52]. In contrast, PCOS animals in the PFD500 and PFD1000 groups had a significantly lower level of MDA but higher SOD and GSH-Px activities. These findings were in agreement with data which were reported the prospect of oxidative stress modulator-natural antioxidants as therapeutic interventions for managing PCOS [53]. However, an increase in SOD activity has also been reported in women with PCOS [54]. A higher level of SOD activity and reduced levels of glutathione peroxidase has been shown to disrupt the efficiency of ROS scavenging in the follicular environment [55]. Therefore, histomorphometric analysis of the ovary and uterine tissues are required to confirm these results
PCOS has been demonstrated can induce histo-architectural changes in the ovary [56] and uterus [57] of rats. In agreement with previous studies on PCOS animal models, fewer numbers of corpus luteum and multiple follicular ovarian cysts were observed in the PC group [58, 59]. Reduction in ovarian weight, uterine length and weight, endometrium thickness, and numbers of the endometrial gland are consistent with decreasing levels of testosterone, FSH, LH, and antioxidants activities. Our study provides additional support for the association between reproductive hormone levels and gonadal morphology in rats with PCOS. Importantly, significant increases in the numbers of corpora lutea, ovarian and uterine weight, endometrium thickness, and numbers of the endometrial gland, together with a decrease in the numbers of cystic follicle were found in the PCC, PFD500, and PFD1000 groups. The appearance of corpora lutea suggesting that these animals have ovulated. Higher levels of progesterone obtained in these groups confirmed that ovulation has occurred. It is important to note that the management of PCOS is aimed mainly at restoring ovulation.
Taken together, it was observed that F. deltoidea effectively ameliorates biochemical hormonal, and histomorphometric changes to levels comparable with those reported in the clomiphene citrate treated rats. These results have further strengthened the hypothesis that a combination of lipid-lowering with insulin-sensitizing agents would achieve better therapeutic effects in the treatment of PCOS.