In the present study we investigated how the suprachiasmatic nucleus (SCN) controls the E(2)-induced PRL surge in female rats. First, the role of vasopressin (VP), a SCN transmitter present in medial preoptic area (MPO) projections and rhythmically released by SCN neurons, as a circadian signal for the E(2)-induced PRL surge was investigated. Using a reverse microdialysis technique, VP was admi...

The phase of the mammalian circadian pacemaker, located in the suprachiasmatic nucleus (SCN), is modulated by a variety of stimuli, most notably the environmental light cycle. Light information is perceived by the circadian pacemaker through glutamate that is released from retinal ganglion cell terminals in the SCN. Other prominent modulatory inputs to the SCN include a serotonergic projection ...

The crystal structure of the complex of lactoperoxidase (LPO) with its physiological substrate thiocyanate (SCN(-)) has been determined at 2.4A resolution. It revealed that the SCN(-) ion is bound to LPO in the distal heme cavity. The observed orientation of the SCN(-) ion shows that the sulfur atom is closer to the heme iron than the nitrogen atom. The nitrogen atom of SCN(-) forms a hydrogen ...

The suprachiasmatic nucleus (SCN) is the principal generator of circadian rhythms and is part of an entrainment system that synchronizes the animal with its environment. Here, we review the possible communication of timing information from the SCN to peripheral tissues involved in regulating fundamental physiological functions as revealed using a viral, transneuronal tract tracer, the pseudorab...

Thiocyanate found in serum ordinarily is the metabolite of cyanide that is inhaled with tobacco smoke and ingested with cyanogenic foods. We investigated the effect of the thiocyanate ion (SCN-) on the ionized magnesium (iMg) and ionized calcium (iCa) results determined with the AVL and Nova magnesium and calcium ion-selective electrodes (ISEs). We analyzed saline and pooled serum with added SC...

The expression of locomotor activity by golden hamsters is temporally controlled by circadian oscillators contained within the suprachiasmatic nucleus (SCN). A genetic mutation has been found that alters the freerunning period of the locomotor activity rhythm from the wild-type value of approximately 24 hours to approximately 20 hours in homozygous mutants. It has been shown previously that a t...

Neuropeptide signaling plays roles in coordinating cellular activities and maintaining robust oscillations within the mammalian suprachiasmatic nucleus (SCN). Prokineticin2 (PK2) is a signaling molecule from the SCN and involves in the generation of circadian locomotor activity. Prokineticin receptor 2 (PKR2), a receptor for PK2, has been shown to be expressed in the SCN. However, very little i...

Individual neurons within the suprachiasmatic nuclei (SCNs) are capable of functioning as autonomous clocks and generating circadian rhythms in the expression of genes that form the molecular clockworks. Limited information is available on how these molecular oscillations in individual clock cells are coordinated to provide for the ensemble rhythmicity that is normally observed from the entire ...

The distribution of vasoactive intestinal polypeptide-like (VIP) immunoreactivity in neurons and processes within the suprachiasmatic nuclei (SCN) of the rat was investigated with light and electron microscopic immunocytochemical techniques. These studies utilized well characterized antisera directed to synthetic vasoactive intestinal polypeptide. Specificity was established by absorption of th...

The immune and the circadian systems interact in a bidirectional fashion. The master circadian oscillator, located in the suprachiasmatic nuclei (SCN) of the hypothalamus, responds to peripheral and local immune stimuli, such as proinflammatory cytokines and bacterial endotoxin. Astrocytes exert several immune functions in the CNS, and there is growing evidence that points toward a role of thes...