Zucker fatty (ZF) rats are considered to be an obese model due to leptin receptor abnormality and such rats show infertility. Pulsatile gonadotropin-releasing hormone/luteinizing hormone (LH) secretion
which is important for follicular development in females
is considered to be controlled by KNDy neurons coexpressing kisspeptin
neurokinin B (NKB)
and dynorphin A (DynA)
encoded by Kiss1
Tac3
and Pdyn
respectively
in the hypothalamic arcuate nucleus (ARC). The purpose of this study is to examine the expression of KNDy neurons in female ZF rats by histochemical approach because pulsatile LH secretion is suppressed. Zucker lean (ZL) rats served as a control group. Animals were ovariectomized and subcutaneously implanted with a silicon tube containing estradiol to produce plasma level of estradiol during diestrus. Plasma LH levels decreased in ZF rats compared with ZL rats. The expressions of each mRNA (Kiss1
Tac3
and Pdyn) and each peptide (kisspeptin
NKB
and DynA) in the ARC significantly decreased in ZF rats compared with ZL rats. However
the number of Kiss1 neurons in the anterior ventral periventricular nucleus did not significantly differ between the two groups. These results suggest that dysfunction of leptin signaling negatively affects KNDy neurons in the ARC
resulting in reproductive dysfunction caused by suppression of the LH pulse.
