In the present study, post-weaning HFD exposure resulted in a marked suppression of ovarian Kiss1 gene expression during prooestrus and oestrus at both PND 42 and PND 70, with reduced kisspeptin-IR in theca layer of antral and preovulatory follicles, suggesting that the ovarian Kiss1 system is down-regulated under conditions of obesity and is associated with reproductive problems, such as ovulatory dysfunction. This evidence concerns the gene KISS1 and obesity due to melanocortin 4 receptor deficiency.