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KMID : 0387519960060010097
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Journal of Maryknoll Hospital
1996 Volume.6 No. 1 p.97 ~ p.107
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Change of the Immunoreactivities and Gene Expression Patterns in the Rat Suprachiasmatic Nucleus According to Day-Night Variation
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김완수.
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Abstract
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Neurons within the SCN appear to function as a circadian clock that controls the timing of many physiological systems. Circadian light stimull also reach to the IGKL which involved in reentraining process to the altered day-night variation. The
purpose
of the present study was to determine whether neuroactive substances within rat SCN and IGL exhibit changes of their immunoreactivities and gene expression pattern according to day-night variations by using immuno-cytochemistry, in situ
hybridization
and image analyzing system. As a control group. adult male Sprague-Dawley rats were placed in individual environmental isolation rooms and exposed to light-dark(LD) cycle. As a experimental groups, animals were housed under the constant
darkness(DD) and
constant light(LL) conditions. Light was provided by 15W fluorescent bulbs and was approximately 350 lux when measured at the enter of the room After approximately 2 weeks of exposure to the lighting conditions, rats were sacrificed for the
immunocytochemistry(ICC) and in situ hybridization(ISH). The fixative for the ICC was 4% paraformaldehyde in 0.1M PB and reaction was performed in the floating method with ABC-perioxidase method. For ISH, the fresh frozen sections were hybridized
35S-dATP labeled oligonucleotide probes. The immunoreactive areas in the SCN and IGL were analyzed with IBAS image analyzer system(Zeiss).
@ES The results were as follows:
@EN 1. VIP and prepro-VIP mRNA levels in the SCN were demonstrated to be higher in the DD group(p<0.01) and lower in the LL grop (p<0.05) than LD group.
2. NPY and prepro-NPY mRNA levels in the IGL was higher in LL than LD(p<0.05)
3. Only light stimuli during D phase of the LD group and subjective night of the DD group induced robust Fos like immunoreactivity(FLI) in the ventrolateral subdivision of SCN. FLI was not found in both SCN and IGL of the control rats which
received
NK-801 before the light stimuli.
4. While 60-90 minutes of light stimuh during D phase induced very little FLI in the IGL, more than 2h of light stimuli induced intense FLI.
These results suggest that expression of neuropeptides in the SCN and IGL changes according to environmental light condition.
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KEYWORD
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