D-Lys-3-GHRP-6 downregulates the hippocampal serotonin HT7 receptors

Background and Aim : We have previously shown that antagonism of the ghrelin receptors in the rat brain impairs memory consolidation. However, the causal mechanisms are not well-known. It is known that ghrelin can influence serotonergic signaling in the brain. We aimed to evaluate the effect of i.c.v injection of a ghrelin receptor antagonist (D-Lys-3-GHRP-6) on the mRNA expression levels of the hippocampal serotonin HT7 receptors.Methods : Fifteen adult male Wistar rats weighing 250 g were implanted with cannulas in their lateral ventricles. Three groups of animals (n=5) received D-Lys-3-GHRP-6 (0.5 and 5nM) or saline. Twenty-four hours thereafter, their hippocampus was removed. The serotonin HT7 receptor gene expression levels were measured using a real-time PCR method.Results : One-way ANOVA indicated a significant decrease in the expression levels of serotonin HT7 receptors. The post-hoc comparison showed that D-Lys-3-GHRP-6 (5nM) downregulated the mRNA expression levels of the hippocampal serotonin HT7 receptors, compared to the control group.Conclusion : It seems that part of the impairing effect of i.c.v injection of D-Lys-3-GHRP-6 on memory consolidation might be due to a decrease in the serotonin HT7 receptors in the hippocampus of rats.

کلیدواژه ها:

D-Lys-3-GHRP-6 ، Hippocampus ، Serotonin HT7 receptor