Calbindin-D28K cells selectively contact intra-SCN neurons
Section snippets
Animals and housing
Subjects were LVG hamsters (Mesocricetus auratus) obtained from Charles River Laboratories. Animals were housed in translucent propylene cages (48×27×20 cm) and provided with ad libitum access to food and water. They were kept in a 14:10 light:dark cycle, with lights on at 08.00 h. The room was kept at 21±1°C. All handling of animals was done in accordance with Institutional Animal Care and Use Committee guidelines of Columbia University.
Perfusion
Hamsters were heavily anesthetized with sodium
Intra-suprachiasmatic CalB connections
CalB cells make selective intra-SCN connections. Figure 1 is a schematic representing the distribution of cells and fibers and the intra-SCN interconnections between the CalB cells and the VIP, AVP, CCK or GRP cells. The SCN is represented at four different levels from rostral to caudal.
Figure 2 shows photomicrographs of representative parts of the SCN, double-labeled for CalB and VIP, AVP, CCK or GRP. The top row shows light microscopic images of 50 μm thick sections through the CalB subregion
Connections of CalB-immunoreactive cells within the SCN
The molecular machinery that generates rhythmicity at the cellular level is being elucidated (Dunlap, 1999, King and Takahashi, 2000, Reppert and Weaver, 2001); however, the mechanisms of entrainment, coupling between entraining cues and oscillators and output are poorly understood. Knowledge of SCN organization is necessary to understand the generation and control of circadian rhythmicity in mammals.
This study focuses on the connections of the CalB cells of the hamster which has several
Acknowledgements
Supported by NIH Grants NS 37919 to R.S. and DK 07328 to L.J.K.
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Structural plasticity of the circadian timing system. An overview from flies to mammals
2015, Frontiers in NeuroendocrinologyCitation Excerpt :In rat, it is partly colocalized with VIP in the most ventral aspect of the SCN where it would define a functionally distinct group within the VIP population (Albers et al., 1991; Romijn et al., 1997; Kawamoto et al., 2003; Guillaumond et al., 2007). In hamster, it is coexpressed in some of the CalB cells (LeSauter et al., 2002). Astrocytes are also important cellular components of the SCN.
Neuroanatomy of the extended circadian rhythm system
2013, Experimental NeurologyCitation Excerpt :The CALB cells in the hamster SCNce contact neurons identifiably VIP-, GRP- or CCK-IR and each of those cell types project back onto the CALB-IR cells. In contrast, VP-IR neurons appear to have no connections with CALB-IR cells (LeSauter et al., 2002). A confocal laser scanning microscopic study (Romijn et al., 1997) analyzed connections between cells representing the major phenotypes in rat SCN, including VP-, VIP-, GRP- and SS-IR neurons.
Neurons identified by NeuN/Fox-3 immunoreactivity have a novel distribution in the hamster and mouse suprachiasmatic nucleus
2011, Brain ResearchCitation Excerpt :VP-IR cells also tend to be scattered elsewhere in the SCN, particularly in the mouse. CCK-IR cells have a distribution similar to that for VP-IR neurons, but are also found ventrolaterally (LeSauter et al., 2002; Silver et al., 1999). CCK has been less widely studied than VP and the extent to which it is present in the SCN of diverse species is not known.
Calcium-binding proteins in the circadian centers of the common marmoset (Callithrix jacchus) and the rock cavy (Kerodon rupestris) brains
2008, Brain Research BulletinCitation Excerpt :For example, it was noticed that the rupture of the circadian rhythm of locomotor activity following exposure to prolonged constant light parallels the suppression of CB expression in the retinorecipient area of the rat SCN [3]. Current statements point to the fact that CB present in the SCN cells are part of a potential intercellular pathway of the SCN population, sustaining local neurons that drive photic information between areas of the nucleus [17,21]. Also, CB expression is negatively correlated to the day length, i.e., the number of CB-positive cells in the SCN increases in hamsters exposed to short photoperiods when compared with hamsters exposed to long photoperiods, supporting the idea that CB-IR neurons in the SCN are involved in the encoding of seasonal information by the SCN [26].