Seasonally Related Metabolic Profile and Regulation during Growth and Reproduction in Goldfish

Date
2022-04
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Abstract
Many fish species are seasonal breeders and undergo an annual cycle of predominant growth and reproductive phases. Seasonal variations are controlled by hormones of the brain-pituitary-peripheral axis and involve changes in gonadal development, growth, and metabolism. Previous studies have demonstrated that the hypothalamic neurohormones gonadotropin-releasing hormone (GnRH) and gonadotropin-inhibitory hormone (GnIH) are among the key regulatory factors involved in the multifactorial control of growth and reproduction in vertebrates. In oviparous species such as fish, significant metabolic energy is needed during reproduction in both female and male to produce hundreds of eggs and millions of sperm. The main goal of my dissertation was to investigate metabolic changes and patterns of energy allocation during growth and reproduction in the goldfish (Carassius auratus). Moreover, I tested the hypothesis that GnRH and GnIH are involved in the regulation of metabolism by investigating the seasonally-related effects of these peptides. An in vivo metabolomics approach was used to investigate the metabolic profile and regulation in male and female goldfish at different stages of the reproductive cycle. Two Liquid Chromatography-Mass Spectrometry (LC-MS) based approaches - metabolic profiling and isotope tracing - provided evidence for distinct patterns of energy allocation during reproduction and growth in goldfish. The findings demonstrate significant differences in the hepatic metabolic profile of three distinct reproductive stages in male and female fish involving carbohydrate, protein, lipid and nucleotide metabolism. Furthermore, the results presented in this study prove that GnRH and GnIH can modulate hepatic metabolism in a sexually-dimorphic and seasonally dependent manner. Tracer-based metabolomics using [U-13C]glucose demonstrate that the activity of pathways of the central carbon metabolism in the liver, gonads and muscle of male and female goldfish are different between growth and reproductive stages. Finally, the findings reveal sex specific differences and similarities in the regulation of metabolism during the annual cycle. Together, the results presented in this dissertation provide novel information and a framework to better understand the hormonally induced metabolic changes that accompany growth and reproduction in fish and other species undergoing seasonal cycles.
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Keywords
Metabolomics, Growth and reproduction, Metabolism, Energy allocation, Fish physiology, Goldfish
Citation
Ladisa, C. (2022). Seasonally related metabolic profile and regulation during growth and reproduction in goldfish (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.