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This study investigates the possibility of glutamate and/or aspartate as an excitatory transmitter in the retinohypothalamic fibers' terminal within the anterior hypothalamus, including the suprachiasmatic nucleus (SCN). We studied the release of 3H-Glu and 3H-Asp from the SCN of rat hypothalamic slices produced by optic nerve stimulation. Stimulation of(More)
Electrical stimulation of the optic nerve evoked two positive waves with short latency, followed by a large negative wave in the suprachiasmatic nucleus of slices of hypothalamus of the rat. The latency to peak of the two positive waves and the large negative wave were 2.7 +/- 0.1, 6.1 +/- 0.1 and 10.3 +/- 0.5 msec, respectively. Only the large negative(More)
The suprachiasmatic nucleus (SCN), which appears to act as a circadian clock, contains a subpopulation of local circuit neurons in which vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), and gastrin releasing peptide (GRP) are colocalized. To determine whether VIP, PHI, and GRP interact within the SCN to produce a signal important for(More)
The rate and pattern of neuronal discharge in the suprachiasmatic nucleus (SCN) during developmental stages were studied and compared with those of the ventromedial (VMH) and the lateral hypothalamus (LHA) using rat hypothalamic slices. The firing rate of the SCN neurons was low on the 7th and 11th days; however, it dramatically increased by the 14th day to(More)
Synchronization between the environmental lighting cycle and the circadian clock in the suprachiasmatic nucleus (SCN) is correlated with Ca2+ increase. The mechanism underlying the increase of Ca2+ and its relation to clock resetting are unknown. To address these issues, we examined the possibility whether inositol 1,4,5-trisphosphate receptor (IP3-R),(More)
In order to elucidate a role of insulin on neurons in the suprachiasmatic nucleus (SCN) involved in the generation of circadian feeding behavior, we examined the effect of insulin on SCN neuronal activity at in vitro condition. Bath application of insulin (1-100 microU) mainly inhibited the SCN neuronal activity, and this inhibitory effect was still(More)
The influence of environmental light-dark cycle (LD) and bilateral enucleation on single neuronal activity in the suprachiasmatic nucleus (SCN) was examined using a hypothalamic slice preparation. Firstly, we reconfirmed previous results that the discharge rate in slices taken from animals kept on normal LD was higher during the light than during the dark(More)
A large population of local circuit neurons within the suprachiasmatic nucleus (SCN) exhibit immunopositive staining for arginine-vasopressin (AVP). AVP has been reported to be released from SCN neurons in a circadian pattern that peaks during the subjective day. Using an in vitro hypothalamic slice preparation, the present study investigated how SCN(More)
The medial preoptic-anterior hypothalamus (MPOA-AH) is necessary for expression of several testosterone-dependent behaviors including a form of hamster scent marking, called flank marking. Since arginine vasopressin (AVP) plays a critical role in the control of flank marking by the MPOA-AH the present study examined whether testosterone can influence the(More)
In order to elucidate the role of cyclic nucleotides in the suprachiasmatic nucleus, we examined the effect of dibutyryl cyclic AMP (c-AMP) and dibutyryl cyclic GMP (c-GMP) on single neuronal activity of the suprachiasmatic nucleus of the rat. A hypothalamic slice about 300 micron thick, including the suprachiasmatic nucleus, was cut coronally using a(More)