Meeting Abstract
The timing of reproduction generally is a critical component of fitness and is related to trophic resources. Ultimately, reproduction is often synchronized with periods of peak food resources for the young, thus benefiting offspring development. Proximately, breeding when these resources are most abundant helps individuals sustain the energetic costs that are associated with expression of reproductive behavior and physiology. Studies manipulating food availability demonstrate the importance of this factor on reproduction, but the physiological and in particular neuroendocrine mechanisms that mediate effects of food availability on the non-mammalian vertebrate hypothalamic-pituitary-gonadal (HPG) axis are poorly understood. These mechanisms may involve a direct role for metabolites (e.g., glucose and fatty acids) related to the energetic state on the HPG axis, in particular the hypothalamus and gonads. Alternatively, or in addition, these mechanisms may be indirect and due to actions of hormones (e.g., leptin and glucocorticoids [GC]) whose secretion responds to the energetic state. Supporting this view, GC secretion often increases during homeostatic challenges such as food restriction. Furthermore, when energy resources are limited, GC can facilitate the organism’s transition from reproductive condition to self-maintenance. A main challenge in determining whether the HPG axis activity is directly or indirectly regulated by energetic signals is that the secretion of hormones such as GC is often affected by homeostatic challenges, but these hormones can in turn profoundly affect an organism’s metabolic state. In this talk we will discuss how food availability influences reproductive physiology and the metabolites, hormones, and neuroendocrine pathways that potentially mediate this influence.
