Retinohypothalamic tract development in the hamster and rat

Speh, Joan C.; Moore, Robert Y.

doi:10.1016/0165-3806(93)90205-o

Cited by 137 publications

(94 citation statements)

References 35 publications

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“…In support of this hypothesis, we note that in non-enucleated rats, the shift from maternal to photic entrainment depends upon the development of functional connectivity between the RHT and SCN, which occurs between P0 and P12 (Duncan et al 1986, Hannibal and Fahrenkrug 2004, Speh and Moore 1993. Moreover, in adults, light may act as a zeitgeber by up-regulating growth factors (e.g., NGF1-A, BDNF) in the SCN (Allen and Earnest 2005, Liang et al 2000, Tanaka et al 1999.…”

Section: Discussionmentioning

confidence: 61%

“…Even at birth in rats, melanopsin-containing retinal ganglion cells are directly responsive to light and form functional connections with the SCN via the RHT (Hannibal andFahrenkrug 2004, Sekaran et al 2005). The strength of connectivity between the RHT and SCN increases over the first postnatal week and becomes adult-like by the end of the second postnatal week (Hannibal andFahrenkrug 2004, Speh andMoore 1993).…”

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confidence: 99%

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The Development of Day-Night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

et al. 2008

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The suprachiasmatic nucleus (SCN) exhibits circadian rhythmicity in fetal and infant rats, but little is known about the consequences of this rhythmicity for infant behavior. Here, in Experiment 1, we measured sleep and wakefulness in rats during the day and night in postnatal day (P)2, P8, P15 and P21 subjects. As early as P2, day-night differences in sleep-wake activity were detected. Nocturnal wakefulness began to emerge around P15 and was reliably expressed by P21. We hypothesized that the process of photic entrainment over the first postnatal week, which depends upon the development of connectivity between the retinohypothalamic tract (RHT) and the SCN, influences the later emergence of nocturnal wakefulness. To test this hypothesis, in Experiment 2 infant rats were enucleated bilaterally at P3 and P11, that is, before and after photic entrainment. Whereas pups enucleated at P11 and tested at P21 exhibited increased wakefulness at night, identical to sham controls, pups enucleated at P3 and tested at P21 exhibited the opposite pattern of increased wakefulness during the day. Pups tested at P28 and P35 exhibited this same pattern of increased daytime wakefulness. All together, these results suggest that prenatal and postnatal experience modulates the development of species-typical circadian sleep-wake patterns. Moreover, we suggest that visual system stimulation, via the RHT's connections with the SCN, exerts an organizational influence on the developing circadian system and, consequently, contributes to the emergence of nocturnality in this species.

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Section: Discussionmentioning

confidence: 61%

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confidence: 99%

The Development of Day-Night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

et al. 2008

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“…In addition, recent findings indicate that neonatal alcohol administration induces apoptotic neurodegeneration of both retinal ganglion cells and neurons in brain regions receiving visual system projections such as the lateral geniculate nucleus (Tenkova et al, 2003). It is noteworthy that the alcohol treatment interval from PDs 4 to 9 was coincident with critical period for the synaptogenesis of RHT projections to the SCN (Speh and Moore, 1993). However, it is unlikely that the observed effects of neonatal alcohol exposure on the photic regulation of circadian behavior are caused by damage to retinal ganglion cells or optic nerve fibers that form the RHT because these structural defects would be expected to decrease, rather than increase, both the rate of reentrainment and phase-shifting responses to light in EtOH animals.…”

Section: Discussionmentioning

confidence: 99%

Long-term effects of neonatal alcohol exposure on photic reentrainment and phase-shifting responses of the activity rhythm in adult rats

Allen

Farnell

Maeng

et al. 2005

Alcohol

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In rats, neonatal alcohol (EtOH) exposure coinciding with the period of rapid brain growth produces structural damage in some brain regions that often persists into adulthood and thus may have longterm consequences in the neural regulation of behavior. Because recent findings indicate that the circadian clock located in the rat suprachiasmatic nucleus is vulnerable to alcohol-induced insults during development, the present study examined the long-term effects of neonatal alcohol exposure on the photic regulation of circadian behavior in adult rats. Rat pups were exposed to alcohol (3.0, 4.5, or 6.0 g·kg -1 ·day -1 ) or isocaloric milk formula on postnatal days 4-9 using artificial-rearing methods. At 2 months of age, animals were housed individually and circadian wheel-running behavior was continuously analyzed to determine the effects of neonatal alcohol treatment on the rate of reentrainment to a 6-h advance in the 12-h light:12-h dark photoperiod and the phase-shifting properties of free-running rhythms in response to discrete light pulses on a background of constant darkness. For all doses, neonatal alcohol exposure had a significant effect in reducing the time for reentrainment such that EtOH-treated rats required four to five fewer days than control animals for stable realignment of the activity rhythm to the shifted light-dark cycle. Coupled with the accelerated rate of reentrainment, the amplitude of light-evoked phase delays at circadian time 14 and advances at circadian time 22 in the 4.5 and 6.0 g·kg -1 ·day -1 EtOH groups was almost twofold greater than that observed in control animals. The present observations indicate that the mechanisms by which photic signals regulate circadian behavior are permanently altered following alcohol exposure during the period of rapid brain development. These long-term alterations in the photic regulation of circadian rhythms may account, at least partially, for some neurobehavioral consequences of prenatal alcohol exposure in humans such as depression.

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“…Specifically, retinal input is much denser in the ventrolateral than in the dorsomedial rat SCN (Speh and Moore, 1993). Light-induced Fos expression in hamsters is concentrated in the CalB subregion, sparse in the dorsolateral area, and very low or not expressed in the dorsomedial SCN (Aronin et al, 1990;Guido et al, 1999;Hastings et al, 1996;Kornhauser et al, 1990;Rusak et al, 1990;Silver et al, 1996).…”

Section: Functional Organization Of the Scnmentioning

confidence: 95%

Calbindin-D28K cells selectively contact intra-SCN neurons

et al. 2002

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Calbindin-D 28K -immunoreactive cells are tightly packed within a discrete region of the caudal aspect of the suprachiasmatic nuclei of hamsters. These cells receive direct retinal input and are Fos-positive in response to a light pulse. Knowledge of their afferent and efferent connections is necessary to understand suprachiasmatic nucleus organization. The first aim of the present study is to identify interconnections between calbindin and other peptidergic cells of the suprachiasmatic nuclei, using epi-and confocal microscopy and intra-suprachiasmatic nucleus tract tracing. The results indicate that essentially all calbindin cells receive numerous appositions from vasoactive intestinal polypeptide (VIP), neuropeptide Y and serotonin fibers and that most receive appositions from gastrin releasing peptide (GRP) and cholecystokinin (CCK) fibers. Reciprocal connections are seen from VIP, GRP and CCK cells but surprisingly, not from dorsomedial vasopressin cells. Injection of biotinylated dextran amine into the suprachiasmatic nucleus indicates that the ventrolateral suprachiasmatic nucleus projects to the entire nucleus, while the dorsal and medial regions of the suprachiasmatic nucleus project densely to most of the nucleus, except to the calbindin region. Analysis of colocalization of the peptides in the calbindin cell region shows that 91% of the substance P cells, 42% of the GRP cells and 60% of the VIP cells in the calbindin subnucleus coexpress calbindin-D 28K .Our results reveal a highly specialized topographical organization of connections among suprachiasmatic nucleus cells. Keywords suprachiasmatic nucleus; calbindin; vasopressin; confocal microscopy; tract tracingThe suprachiasmatic nuclei (SCN) are the locus of the brain clock regulating circadian rhythms in mammals (reviewed in Silver and Moore, 1998). In rodents, these paired hypothalamic nuclei are each composed of about 8000 neurons that are heterogeneous in their content of neuronal antigens (van den Pol, 1980;van den Pol and Tsujimoto, 1985). Some of the neuropeptides that have been identified to date in the rodent SCN are vasopressin (AVP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine, gastrin releasing peptide (GRP), sub-stance P (SP), cholecystokinin (CCK) and somatostatin. We have reported that a subregion in the caudal SCN is characterized by the (Silver et al., 1996). These cells are densely packed, receive direct retinal synaptic input (Bryant et al., 2000) and are responsive to photic stimuli, with about 80% of the cells showing Fos-like immunoreactivity (ir) following a light pulse given during subjective night (Silver et al., 1996). The foregoing evidence indicates these CalB cells are on the input pathway for photic stimuli reaching the SCN.The function of this subregion of the SCN has been examined in hamsters. Animals with lesions that destroyed the CalB subnucleus, but spared other compartments of the SCN, lost their locomotor activity rhythm. Animals with partial bilateral SCN lesions sparing part ...

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Retinohypothalamic tract development in the hamster and rat

Cited by 137 publications

References 35 publications

The Development of Day-Night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

The Development of Day-Night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

Long-term effects of neonatal alcohol exposure on photic reentrainment and phase-shifting responses of the activity rhythm in adult rats

Calbindin-D28K cells selectively contact intra-SCN neurons

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