Introduction: The neuropeptide Y (NPY) in the neural circuits of the hypothalamus has a
stimulating effect on reproductive activities in mammals. Kisspeptin (KiSS1) is a quintessential
neurotransmitter in the reproductive axis which directly stimulates gonadotropin-releasing
hormone neurons in the hypothalamus. The distribution of KiSS1 expressing cells in the pituitary
was described previously. Despite earlier reports showing the KiSS1 receptor, G-protein coupled
receptor 54 (GPR54) expression in the pituitary, the potential physiological roles of kisspeptin
at this gland have remained obscure. Accordingly, this study investigated the role of NPY on the
relative expression of Kiss1 and Gpr54 genes in the pituitary gland in male Wistar rats.
Methods: In general, 20 male Wistar rats weighing 200-250 g in 4 groups (5 in each group)
received saline, NPY (2.3 nM), BIBP3226 (NPY receptor antagonist, 7.8 nM), and NPY+
BIBP3226. Then, they received the simultaneous injection of these molecules through the third
ventricle of the brain. Finally, the relative mean expressions of Kiss1 and Gpr54 genes in the
anterior pituitary were quantitatively analyzed by the real-time polymerase chain reaction.
Results: The central injection of NPY increased the relative mean expressions of Kiss1 and
Gpr54 genes in the pituitary gland compared to the control group although the injection of
BIBP3226 eradicated these effects. However, the gene expression of Gpr54 in the rats receiving
NPY coupled with BIBP3226 in hypophysis in comparison to the group receiving only NPY
demonstrated a significant reduction (P<0.05).
Conclusion: Overall, the central injection of NPY stimulated the gene expression of Kiss1 and
Gpr54 in the pituitary gland.