Endocrine Abstracts

Circadian, 24 hr, timing is a conserved feature of physioloogy and behaviour across eukaryotes. In mammals the principal clock resides in the suprachiasmatic nuclei of the hypothalamus (SCN). Through neural and endocrine linkages the SCN direct the daily temporal programme of brain and peripheral tissues. The core clockwork is based on a cell-autonomous, self-sustaining feedback loop of gene expression. Mutations of mammalian homologues of 'clock' genes identified in lower species lead to disordered circadian patterning in rodents and humans. More recently, mutations of intercellular signalling pathways within the SCN have also been shown to disrupt circadian timing. This presentation will review recent developments regarding the function of clock genes and their products in circadian timing, and will also describe studies using DNA micro-array approaches to analyse SCN-dependent circadian regulation of gene expression in peripheral tissues.