RESEARCH PROJECTS

Investigation of the Equine Molecular Clock in a Fibroblast
Cell Line, Adipose Tissue and Peripheral Blood

Barbara Murphy - Graduate Research Assistant

In order to align physiological function with the solar day, molecular clock mechanisms have evolved that are sensitive to light and allow mammals to anticipate periods of activity. The central pacemaker of the mammalian circadian timing system, located in the suprachiasmatic nucleus (SCN) of the hypothalamus, receives light information via the retino-hypothalamic tract and transmits the timing signal to peripheral tissues.  This timing information serves to synchronize self-sustained independent circadian (approximately 24 hour) oscillators that are now thought to exist within each cell of almost every tissue. In this way, peripheral tissues can adapt their specific function to the correct time of day by means of tissue-specific circadian regulation of transcription.  

This clockwork system results in the circadian rhythms associated with most physiological processes including body temperature, hormone secretion, blood pressure, heart rate, respiratory rate, metabolism, alertness and immune cell function.  Disruption of these rhythms occurs as a result of abrupt changes in the light/dark cycle, as is the case with transmeridian travel. “Jet lag” is a conflict between the new light/dark cycle and the previously entrained program of the internal clock and has serious implications for the human or equine athlete hoping to perform optimally in a new time zone.  

One goal of this research is to determine the effects of circadian time disruption at a molecular and physiological level in the horse and to evaluate the impact this may have on performance. Rhythmic cycling of clock genes has previously been demonstrated in peripheral blood of rats and humans.  Current research therefore is focused on identifying the expression of clock genes in various tissues of the horse, including blood.