Combinatorial Contributions of Kisspeptin Neurons and GnRH Neurons to Male Infertility

Fertility varies within a population due to combinatorial contributions of heritable neuroendocrine variations. A better understanding of these variations can lead to mathematical models that could predict which combination of neuroendocrine traits may improve fertility. Our laboratory has identified neuroendocrine traits responsible for fertility variations within our white-footed mouse population: kisspeptin neuronal count and GnRH neuronal count. The kiss neuron and GnRH neuron, both located in the hypothalamus, regulate the HPG-axis. Each of these traits has been found to be variable, but we do not know the combined effect of the two traits on fertility. This study investigates the combined effect of kisspeptin and GnRH neuronal counts using a correlation study. Correlation between the two neurons would suggest that the variation in one trait is causing variation in the other. No correlation would suggest that the two neuroendocrine traits independently impact fertility. Testes mass and seminal vesicles mass were used as an indicator of fertility level to study the effect of immunoreactive (IR) kisspeptin neuron counts and IR-GnRH neuron counts. First, there was no significant correlation between IRkisspeptin neuron count and IR-GnRH neuron count, indicating that the two variables may have independent affects on fertility. Second, there was a significant interaction of the two variables in affecting fertility. This suggests that the two variables combined have an effect on fertility that neither has alone. Further statistical analysis and increased sample size is necessary. Overall results suggest that both kisspeptin neurons and GnRH neurons are both significant in determining variation in the level of fertility in this population of Peromyscus leucopus.