GSE65475
Transcriptome profiling of the ovine pars tuberalis in long and short photoperiod conditions
Persistent free-running circannual (circa 1-year) rhythms have  evolved in animals to regulate hormone cycles and time annual reproduction.  In mammals, these are synchronized by environmental photoperiod and the  melatonin signal. Long summer-like photoperiods (LP) activates thyrotrophs  and thyroid-stimulating hormone (TSH) expression in the melatonin target  tissue, the pars tuberalis (PT) region of the pituitary gland, driven by the  transcriptional co-activator EYA3. TSH in turn stimulates thyroid hormone  (TH) conversion in hypothalamic ependymal tanycytes, thus timing breeding  seasons. In contrast to our new knowledge defining photoperiodic input, it is  still not known which cells, tissues and pathways generate the underlying  circannual cycle. We used seasonal sheep to characterise the circannual cycle, transferring animals from short winter-like photoperiods (SP)  to prolonged LP conditions, and assaying prolactin to track circannual phase  in individual animals. Using RNA-seq, we profiled PT cells at different phases of  the circannual cycle, and defined extensive changes of cellular-remodeling  pathways and genes encoding synaptic guidance proteins in the PT. Overall design: Short photoperiod (SP) - 5 samples, Long photoperiod (LP) day 1 - 6 samples, LP day 7 - 6 samples, LP day 28 - 6 samples