Circadian rhythms are biochemical, physiological, or behavioural over 24 hours. The avian circadian system is complex, involving numerous oscillators in the brain. I characterised two hypothalamic input mechanism (melatonin receptors and light) and one output mechanism (vasotocin) in the zebra finch. Melatonin receptors were cloned and expression levels investigated in the brain and in peripheral tissues. Receptors were found in all tissues, with some pronounced rhythmic mRNA expression. Tissue-specific differences in temporal distribution, peak expression and amplitude suggests melatonin have varied roles in different tissues and different receptors control/influence these roles. Effect of light in the hypothalamus was investigated by exposing light into the dark phase of an LD cycle and studying the difference in C-FOS expression. C-FOS was found in hypothalamic nuclei associated with photic transduction. C-FOS-IR cells were also found in the two known avian hypothalamic oscillators, the LHN and SCN. Arginine-Vasotocin is a neuropeptide involved in numerous bodily and nervous tissue functions, secreted within the hypothalamus and pituitary gland. Immunofluorescent experiments showed marked differences in expression, as different zeitgeber times and between species. This study has improved our understanding of avian circadian systems, providing new insights into the hypothalamic oscillator of a complex circadian organisation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:545366 |
| Date | January 2011 |
| Creators | Jones, Catherine Linda |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/3132/ |
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