The suprachiasmatic nucleus and intergeniculate leaflet ofArvicanthis niloticus, a diurnal murid rodent from East Africa

Smale, Laura; Boverhof, Josh

doi:10.1002/(sici)1096-9861(19990111)403:2<190::aid-cne4>3.0.co;2-k

Cited by 70 publications

(41 citation statements)

References 95 publications

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“…Histologically, the SCN are roughly subdivided into two distinct regions: a dorsomedial part expressing arginine vasopressin (AVP) and a ventrolateral part expressing vasoactive intestinal polypeptide (VIP) and/or gastrin-releasing peptide (GRP). This pattern seems to be shared by both diurnal and nocturnal mammals (Inouye and Shibata 1994;Smale and Boverhof 1999). Thus, it seems unlikely that a different organization at the neuropeptide level can account for different circadian organization between diurnal and nocturnal species.…”

Section: Introductioncontrasting

confidence: 99%

“…Our results, together with results by Smale and Boverhof (1999), do not support the hypothesis that a different cellular organization could explain why Arvicanthis is diurnal. Indeed, the organization of the SCN of A. ansorgei is grossly similar to that of the mouse, rat or human with respect to either size, neuropeptide expression or distribution of cell types (Abrahamson and Moore 2001;Inouye and Shibata 1994;Mai et al 1991).…”

Section: Discussionsupporting

confidence: 60%

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Phenotype of Per1- and Per2- expressing neurons in the suprachiasmatic nucleus of a diurnal rodent ( Arvicanthis ansorgei ): comparison with a nocturnal species, the rat

Dardente

Klosen

Caldelas

et al. 2002

Cell and Tissue Research

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In mammals, the suprachiasmatic nuclei (SCN) are the site of the master circadian pacemaker whose molecular core mechanism is based on interlocking transcriptional/translational feedback loops involving clock genes. Among clock genes, Per1 and Per2 are important for both the maintenance of circadian rhythmicity and entrainment to light cues. Several circadian rhythms (e.g., locomotor activity) present opposite patterns in diurnal and nocturnal species. To test whether a differential cellular expression of clock genes in the SCN could constitute the neural substrate leading to diurnal or nocturnal behavior, we identified, by single or double non-radioactive hybridizations, the phenotype of neurons expressing Per1 and Per2 during the day in a diurnal species, Arvicanthis ansorgei, and in a nocturnal species, the rat (Rattus norvegicus). We show that in both species, expression of Per1 and Per2 is mostly restricted to the dorsomedial part of the SCN, often coexpressed with arginine vasopressin (AVP). A few vasoactive intestinal polypeptide (VIP) neurons were also shown to express Per1 and Per2. This differential expression of Per1 and Per2 in AVP and VIP neurons is more distinct in A. ansorgei than in the rat. Thus, our data suggest a major role for the dorsomedial part of the SCN in the maintenance of circadian rhythmicity. Furthermore, the similar diurnal pattern of Per1 and Per2 expression in diurnal and nocturnal rodents suggests that the circadian organization of locomotor activity rhythms probably relies on differential cellular integration mechanisms downstream of the clock.

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Section: Introductioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 60%

Phenotype of Per1- and Per2- expressing neurons in the suprachiasmatic nucleus of a diurnal rodent ( Arvicanthis ansorgei ): comparison with a nocturnal species, the rat

Dardente

Klosen

Caldelas

et al. 2002

Cell and Tissue Research

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“…It is possible that these sites receive information about light directly from the IGL or via pathways affected by IGL lesions (e.g., orexinergic pathways). Different IGL neurons express neuropeptide Y (NPY) or enkephalin (Enk) [35]; we are currently testing the hypothesis that one or both of these cell types project to downstream areas (e.g., OPT) to modulate neural and behavioral responses to light.…”

Section: Discussionmentioning

confidence: 99%

Intergeniculate leaflet lesions result in differential activation of brain regions following the presentation of photic stimuli in Nile grass rats

Gall

Yan

Smale

et al. 2014

Neuroscience Letters

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The intergeniculate leaflet (IGL) plays an important role in the entrainment of circadian rhythms and the mediation of acute behavioral responses to light (i.e., masking). Recently, we reported that IGL lesions in diurnal grass rats result in a reversal in masking responses to light as compared to controls. Here, we used Fos as a marker of neural activation to examine the mechanisms by which the IGL may influence this masking effect of light in grass rats. Specifically, we examined the patterns of Fos activation in retinorecipient areas and in brain regions that receive IGL inputs following 1-h light pulses given during the early night in IGL-lesioned and sham-operated grass rats. Three patterns emerged: (1) IGL lesions had no effect on the Fos response to light, (2) IGL lesions resulted in a reversal in Fos responses to light, and (3) IGL lesions resulted in a lack of a Fos response to light. Of specific interest were the suprachiasmatic nucleus (SCN) and the olivary pretectal nucleus (OPT), both of which are retinorecipient and connect reciprocally with the IGL. Light-induced Fos expression in the SCN was unaffected by IGL lesions, whereas the OPT exhibited a significant reduction in Fos expression following a light pulse in animals with IGL lesions. Altogether, our results suggest that the OPT, but not the SCN, exhibits a reversal in Fos responses to light following IGL lesions that reverse masking responses in diurnal grass rats. Our results suggest that interconnections between the IGL and downstream brain areas (e.g., OPT) may play a role in determining the direction of the behavioral response to light.

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“…VIP+ cells were seen within the core region of the SCN of grass rats and SD rats, as has been described previously (Smale and Boverhof, 1999;Moore et al, 2002) (Fig. 4).…”

Section: Vip+ Cells Fibers and Appositions With Th+ Cellsmentioning

confidence: 97%

Tyrosine hydroxylase positive neurons and their contacts with vasoactive intestinal polypeptide-containing fibers in the hypothalamus of the diurnal murid rodent, Arvicanthis niloticus

Mahoney

Ramanathan

Smale

2007

Journal of Chemical Neuroanatomy

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The suprachiasmatic nucleus and intergeniculate leaflet ofArvicanthis niloticus, a diurnal murid rodent from East Africa

Cited by 70 publications

References 95 publications

Phenotype of Per1- and Per2- expressing neurons in the suprachiasmatic nucleus of a diurnal rodent ( Arvicanthis ansorgei ): comparison with a nocturnal species, the rat

Phenotype of Per1- and Per2- expressing neurons in the suprachiasmatic nucleus of a diurnal rodent ( Arvicanthis ansorgei ): comparison with a nocturnal species, the rat

Intergeniculate leaflet lesions result in differential activation of brain regions following the presentation of photic stimuli in Nile grass rats

Tyrosine hydroxylase positive neurons and their contacts with vasoactive intestinal polypeptide-containing fibers in the hypothalamus of the diurnal murid rodent, Arvicanthis niloticus

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