Characterization of the histological changes in ovaries of Goto-Kakizaki diabetic rats

Goto-Kakizaki (GK) rats are a useful animal model for studying type 2 diabetes mellitus (T2DM). However, this strain of rats exhibits poor fertility, so it is difficult to expand colonies. Based on previous studies, it was hypothesized that alterations in the oestrous cycle of diabetic rats are related to ovarian histology. The aim of this study was to determine the histology of the ovaries of diabetic rats compared to nondiabetic rats to understand the poor fertility of this strain of diabetic rats. An experimental study was thus conducted. Eight GK rats and eight Wistar rats were utilized. The rats were age-adjusted into two groups called “young rats” and “mature rats” at two and fourteen months of age, respectively. After sacrificing the rats, the ovaries were dissected and processed by fixation and paraffin embedding to perform the histological study. The results included the number of corpora lutea and the percentage of follicular fraction in each ovary, as well as qualitative data such as the presence of follicles in different stages of development. Our findings revealed differences between GK and Wistar rats. The ovarian histological findings were related to the presence of T2DM, polycystic ovary syndrome and poor fertility in female GK rats; the link between these pathologies is insulin resistance. Future lines of investigation into metabolic treatment, which may help improve insulin resistance, could also benefit the previously described pathologies in female GK rats.