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Portland State University

Biological rhythms

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Full-Text Articles in Neuroscience and Neurobiology

Neurobiology Of Seasonal Life-History Transitions, Ashley Rae Lucas Sep 2015

Neurobiology Of Seasonal Life-History Transitions, Ashley Rae Lucas

Dissertations and Theses

Many animals exhibit seasonal changes in life-history stages, and these seasonal transitions are often accompanied by dramatic switches in behavior. While the neuroendocrine mechanisms that regulate such behavioral transitions are poorly understood, arginine vasotocin (AVT) and neuropeptide Y (NPY) are excellent candidates because they regulate reproductive and feeding behavior, respectively. In this study, I asked if seasonal changes in AVT and/or NPY are concomitant with spring migration away from the breeding grounds, as male and female red-sided garter snakes (Thamnophis sirtalis parietalis) are transitioning from reproductive to non-reproductive behavior during this time. To address this question, I collected …


Seasonal And Sex Differences In The Effects Of Melatonin On Brain Arginine Vasotocin In Green Treefrogs (Hyla Cinerea): Relationship To Melatonin Receptor 1a, Christina Marie Howard May 2014

Seasonal And Sex Differences In The Effects Of Melatonin On Brain Arginine Vasotocin In Green Treefrogs (Hyla Cinerea): Relationship To Melatonin Receptor 1a, Christina Marie Howard

Dissertations and Theses

Critical life history events such as breeding, migration and hibernation must take place in the correct environmental context to minimize deleterious consequences on survival and reproductive fitness. Neuroendocrine mechanisms synchronizing internal physiological states with extrinsic environmental cues are vital to timing life history events appropriately. Secretion of the pineal hormone melatonin is sensitive to light and temperature cues, which provides a physiological indicator of time of day and time of year for organisms. Melatonin influences seasonal reproduction in a variety of vertebrates, likely by altering the synthesis and/or release of reproductive neuropeptides in the brain. The neuropeptides arginine vasotocin and …