Circadian group – University of Copenhagen

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Neuropsychiatry > Research > Circadian group

Research

Our group is investigating the function and regulation of circadian rhythm generating centers in the brain and eye. We map the neuroanatomical connections between the centers, detect neurotransmitters and receptors and study functional gene expression after light stimulation.

A major advance in the field is the newly detected photoreceptor in the retina containing the photopigment melanopsin, which transmits light information from the retina to the circadian centers in the brain. This optic system is called the non-image forming optic system, because it transmits luminance information to the brain. We work with a knock–out mouse, which does not develop the classical rod and cones and only possesses the non-image forming optic system.

We have recently detected two peripheral oscillators in the neocortex and cerebellar cortex of the rat and mouse. We are now investigating how the information from the central oscillator located in the suprachiasmatic nucleus (SCN) of the hypothalamus is transmitted to these oscillators.

A major target center for the SCN is the melatonin producing pineal gland. We are investigating the molecular mechanism activating the genes encoding the rate liming enzymes in the rat pineal gland.

Our techniques are neuroanatomical tracing, immunohistochemistry, in situ hybridization, western blot, quantitative reverse transciptase-polymerase chain reaction, and gene silencing using shor hairpin constructs.

We work together with research groups at the National Institutes of Healt, Bethesda, MA, USA, University of Alberta, Edmonton, Canada, and University of Strasbourg, France.

Figure. The mammalian circadian photoneuroendocrine system. The endogenous circadian clock resides in the suprachiasmatic nucleus (SCN) located above the optic chiasm (OC). From the SCN, a multisynaptic pathway passing the paraventricular nucleus (PVN), the periaqueductal gray (PAG), the intermediolateral nuclei (IML) of the spinal cord and the superior cervical ganglia (SCG) sends projections to the pineal gland (P) via the internal carotid nerve (ICN) and the conarian nerves (CN). Light controls the period of the rhythm through the retinohypothalamic projection (RHP) (1).