Submitted to: Comparative Endocrinology International Congress Abstracts
Publication Type: Proceedings
Publication Acceptance Date: 4/10/2005
Publication Date: 5/15/2005
Citation: Leder, E.H., Silverstein, J. 2005. Expression of neuropeptides involved in energy homeostasis in developing rainbow trout. Comparative Endocrinology International Congress Abstracts. Abstract 3.9, Boston, MA 05/23 - 05/28/2005.
Technical Abstract: In adult mammals, the regulation of energy homeostasis occurs through the action of several neuropeptides. Orexigenic neuropeptides such as neuropeptide Y (NPY) and agouti-related peptide (AGRP) are co-expressed in hypothalamic neurons in response to energy debt. Conversely, anorexigenic peptides such as cocaine- and amphetamine-regulated transcript (CART) and alpha-melanocortin (a-MSH), derived from its precursor pro-opiomelanocortin (POMC), are also co-expressed in different hypothalamic neurons and act to inhibit feeding. This energy balance system is in place before parturition as expression of these transcripts was observed in fetal sheep. Teleost fish also possess these neuropeptides and there is a high degree of conservation in gene sequence and structure. Initial studies on energy homeostasis in goldfish and zebrafish have demonstrated that these peptides may have similar roles in fish. As part of the investigation of the energy balance system in rainbow trout, we determined the mRNA levels of neuropeptides involved in energy homeostasis during development of rainbow trout. Since larval fish derive energy endogenously from the yolk sac, they may not have the same energy requirements as those feeding exogenously. To examine this, fish were collected at the eyed-egg stage, post-hatch, just prior to exogenous feeding, and 1 week after exogenous feeding. Expression levels in whole fish at each stage were determined for AGRP, NPY, CART, and POMC using real-time PCR. There was a significant increase in AGRP, CART, and POMC mRNA after exogenous feeding compared to the eyed-egg stage. Feeding fish also had significantly higher levels of NPY, AGRP, and CART mRNA than fish at hatching.