At different stages of the oestrous cycle were fixed overnight in
At different stages of the oestrous cycle were fixed overnight in 4 paraformaldehyde at 4 and routinely processed forThe results were expressed PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27488460 as the means ?SEMs, and the analyses were performed using the Statistical Package for the Social Science (SPSS) 17.0 software. The comparisons between the HFD and NCD groups regarding body weight, puberty onset, the level of Kiss1, GPR54, GDF9, BMP15, FSHR, PTGS2 mRNA, and the immunostaining intensity of kisspeptin/GPR54 were statistically analysed using a two-sample t-test. The relative abundance between different oestrous stages within an experimental group was compared by a one-way analysis of variance (ANOVA). The effect of HFD on the regularity of the oestrous cycleZhou et al. Reproductive Biology and Endocrinology 2014, 12:127 http://www.rbej.com/content/12/1/Page 4 ofwas tested using the Chi-squared test. P values <0.05 were considered statistically significant.Effects of HFD exposure on oestrous cyclicity PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27797473 and expression of ovulation-related genesResultsEffect of HFD exposure on body weight and puberty NSC309132 site onsetBefore the dietary treatment, the mean body weights ?SEMs for the HFD and NCD groups were not significantly different (HFD: 48.3 ?0.8 vs NCD: 47.8 ?0.9; Figure 1A; P > 0.05). At 6 weeks of age (PND 42), the HFD group had a significantly higher body weight compared with the controls (HFD: 179.4 ?4.0 vs NCD: 160.2 ?2.7; Figure 1A; P < 0.05). Similarly, feeding an HFD further increased the body weight at 10 weeks of age (PND 70) compared with the controls (HFD: 268.7 ?6.4 vs NCD: 234.0 ?2.8; Figure 1A; P < 0.05). Exposure of the animals to the HFD resulted in a significant advance in the onset of puberty (HFD: 31.8 ?0.3 vs NCD: 35.4 ?0.3; Figure 1B; P < 0.05).Post-weaning HFD exposure had a negative effect on oestrous cyclicity (Figure 2). In puberty, the majority (83.3 ) of the NCD controls had normal 4?-day oestrous cycles, whereas only 38.9 of HFD rats showed regular cyclicity. This disruption was also demonstrated in adulthood, with 77.8 of the NCD rats showing normal cyclicity compared to only 27.8 in the HFD group. The HFD rats had a significantly lower percentage of normal cyclicity during both puberty and adulthood compared with the NCD controls. At late prooestrus, expression levels of GDF9, FSHR and PTGS2 in the HFD rats were lower at both PND 42 and PND 70 (Figure 3A, C and D), whereas the expression of BMP15 only showed significant difference between the two groups at PND 42 (Figure 3B).Effects of HFD exposure on expression of Kiss1/GPRThe expression of Kiss1 and GPR54 in the ovary was analysed in rats fed the HFD or the NCD. The results are shown in Figures 4 and 5. At PND 42, significant reductions in Kiss1 expression were detected at prooestrus and oestrus in the ovaries of the HFD rats compared with the NCD rats (Figure 5A). Similar suppression of Kiss1 mRNA was also observed in the HFD rats at PND 70, with a significant reduction at prooestrus, oestrus and metoestrus (Figure 5B). These data demonstrate the down-regulation of the Kiss1 gene in the HFD rats during follicle maturation and ovulation. In contrast, administration of the HFD did not significantly alter the GPR54 mRNA expression compared to the controls at any stage of the oestrous cycle at either PND 42 or PND 70 (Figure 5C and D). At both PND 42 and PND 70, the expression levels of Kiss1 and GPR54 mRNA were relative high during prooestrus within the NCD groups atFigure 1 Effects of postweaning exposure to.