Effects of Kelulut Honey on Oestrus Cycle Regulation and Histomorphological Changes in Letrozole-Induced Polycystic Ovary Syndrome Rats: A Preliminary Study

Abstract

Polycystic ovary syndrome (PCOS) is a complex reproductive, metabolic, and endocrine disorder that affects women of reproductive age. Kelulut honey is stingless bee honey that possesses anti-inflammatory, anti-cancer, anti-diabetic, and potent antioxidative activities in most conditions. However, its value in improving PCOS remains to be elucidated. Thus, this preliminary study aimed to determine the effective dose of Kelulut honey in oestrus cycle regulation and ovarian histomorphological changes in letrozole-induced PCOS rats. PCOS was induced in all-female Sprague Dawley (SD) rats with 1 mg/kg/day of letrozole except for the control group for 21 days. Kelulut honey was then orally administered to the PCOS rats at the dose of 0.5, 1, or 2 g/kg/day, respectively, for 35 days. The oestrous cycle was determined through vaginal smears, while ovarian histomorphological changes were observed by haematoxylin and eosin (H&E) staining. The untreated PCOS rats were characterised by irregular oestrous cyclicity, hyperglycaemia, and aberrant ovarian histology. In this study, Kelulut honey (1 g/kg/day) increased the number of corpus luteum and antral follicles (p < 0.05), improved the cystic follicle, and normalised the oestrus cycle (p < 0.05). This preliminary study demonstrated that Kelulut honey, particularly at a dose of 1 g/kg/day, has the potential to alleviate oestrus cycle dysregulation and ovarian histomorphological changes occurring in PCOS.

Keywords: Kelulut honey; PCOS; oestrous cycle; ovary.

Figure A1

Effects of letrozole treatment on (a) percentage of dioestrous days and (b) blood glucose levels. NC: normal control; LE: letrozole-induced PCOS. * p < 0.05 compared with normal control group, n = 4 per group.

Figure A2

Effects of letrozole treatment on (a) corpus luteum, (b) atretic follicle, (c) cystic follicle, and (d) antral follicle. NC: normal control; LE: letrozole-induced PCOS. * p < 0.05 compared with normal control group, n = 4 per group.

Figure A3

Rat vaginal epithelium staining in different stages of estrus cycle (A) proestrus, (B) estrus, (C) metestrus, and (D) diestrus. Magnification 10×. Scale bar = 100 µm.

Figure 1

Effects of Kelulut honey on (a) blood glucose levels and (b) body weight gain. NC: normal control; PCOS: Untreated PCOS; KH0.5: PCOS treated with 0.5 g/kg/day of Kelulut honey; KH1: PCOS treated with 1 g/kg/day of Kelulut honey; KH2: PCOS treated with 2 g/kg/day of Kelulut honey. ^a p < 0.05 significance against the normal control group. Different colors denote different groups.

Figure 2

Effects of Kelulut honey treatment on the percentage of dioestrous days. NC: normal control; PCOS: Untreated PCOS; KH0.5: PCOS treated with 0.5 g/kg/day of Kelulut honey; KH1: PCOS treated with 1 g/kg/day of Kelulut honey; KH2: PCOS treated with 2 g/kg/day of Kelulut honey. ^a p < 0.05 significance against the untreated PCOS group. Different colors denote different groups.

Figure 3

Effects of Kelulut honey treatment on ovarian histology. NC: normal control; PCOS: PCOS Control; KH0.5: 0.5 g/kg/day of Kelulut honey; KH1: 1 g/kg/day of Kelulut honey; KH2: 2 g/kg/day of Kelulut honey; CL: corpus luteum; ANF: antral follicle; ATF: atretic follicle; CF: cystic follicle. Magnification 40×. Scale bar = 200 µm and 1 mm.

Figure 4

Effects of Kelulut honey treatment on (a) corpus luteum (b) atretic follicle, (c) cystic follicle, and (d) antral follicle counts. NC: normal control; PCOS: Untreated PCOS; KH0.5: PCOS treated with 0.5 g/kg/day of Kelulut honey; KH1: PCOS treated with 1 g/kg/day of Kelulut honey; KH2: PCOS treated with 2 g/kg/day of Kelulut honey. ^a p < 0.05 significance against untreated PCOS group, ^b p < 0.05 significance against KH0.5 and KH2. Different colors denote different groups.