This reduction of GnRH release is the basis of nutritional infertility. GnRH release is unknown. It is unlikely that GnRH neurons directly detect cues pertaining to the metabolic status of an animal. Instead, metabolic cues probably are detected elsewhere and relayed to GnRH neurons via intermediary neuronal systems. Some of these systems also receive signals from circulating gonadal steroid hormones which are known to be potent inhibitors of GnRH release.
Metabolic challenges appear to further enhance the inhibitory effects of steroids on GnRH release.
Classical neuronal systems including norepinephrine and neuropeptide Y may be components of the neural circuitry linking nutrition and reproduction. Additionally, a plethora of newly-identified neuropeptides that influence feeding behavior significantly increases the number of possible neurochemicals that might mediate these effects. My research focuses on understanding the neural circuitry that receives and transmits information about metabolic status and steroid hormone milieu to GnRH neurons to affect their activity. Current studies employ cellular techniques such as immunocytochemistry and neuronal tract tracing. Molecular techniques including in situ hybridization are use to examine the effects of metabolic challenges on gene expression in these neurochemical systems.