• 생명과학회지
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• 제23권6호
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• pp.804-811
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• 2013

Melanopsin은 옵신과 비슷한 광색소로 망막 광민감성 신경절 세포에서 적은 비율로 발견 된다. Melanopsin은 일주기 리듬조절에 관여 하고 동공반사를 조절한다. 이번 연구의 목적은 melanopsin이 망막 이외의 중추 시각계 에서도 발견 되는지를 알아 보는 것이다. 우리는 생쥐 시각 피질에 존재하는 melanopsin을 가지는 신경세포를 면역조직화학법을 통해 염색하여 melanopsin의 분포와 형태를 분석하였다. Melanopsin 면역반응은 핵을 제외한 신경세포의 세포체에서 일어났다. 우리는 melanopsin이 성체 생쥐의 시각 피질의 2,3층에서 높은 밀도로 모여서 존재하는 것을 확인했다. 시각 피질 1층에서 melanopsin 면역반응을 보인 신경세포는 드물게 발견 되었다. 생쥐 시각 피질에서 발견된 melanopsin의 세포종류는 주로 round/oval 세포였으나, vertical fusiform 그리고 pyramidal 세포 등도 드물게 발견 되었다. 염색된 세포들의 분포는 특이적이지 않았다. 우리의 실험 데이터로 melanopsin이 시각피질에도 분포한다는 것을 알 수 있었다. 또한, melanopsin을 가지는 신경세포는 nitric oxide synthase, calbindin and parvalbumin과도 같이 발현 되는 것을 관찰했다. 이러한 실험결과는 망막 이외의 부분에서 발견되는 melanopsin의 기능에 대한 연구가 필요함을 야기한다.

• Molecules and Cells
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• 제23권2호
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• pp.215-219
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• 2007

In mammals light input resets the central clock of the suprachiasmatic nucleus by inducing secretion of pituitary adenylate cyclase-activating polypeptide (PACAP) from retinal ganglion cells (RGCs). We previously showed that thyroid transcription factor 1 (TTF-1), a homeodomain-containing transcription factor, specifically regulates PACAP gene expression in the rat hypothalamus. In the present study we examined the expression of TTF-1 in PACAP-synthesizing retinal cells. Fluorescence in situ hybridization (FISH) showed that it is abundantly expressed in RGCs of the superior region of the retina, but in only a small subset of RGCs in the inferior region. Double FISH experiments revealed that TTF-1 is exclusively expressed in PACAP-producing RGCs. These results suggest that TTF-1 plays a regulatory role in PACAP-expressing retinal ganglion cells.

• 한국수정란이식학회지
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• 제24권4호
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• pp.237-247
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• 2009

Melatonin (N-acetyl-5-methoxytryptamine) is the major neurohormone secreted during the night by the vertebrate pineal gland. The circadian pattern of pineal melatonin secretion is related to the biological clock within the suprachiasmatic nucleus (SCN) of the hypothalamus in mammals. The SCN coordinates the body's rhythms to the environmental light-dark cycle in response to light perceived by the retina, which acts mainly on retinal ganglion cells that contain the photopigment melanopsin. Calbindin-D9k (CaBP-9k) is a member of the S100 family of intracellular calcium- binding proteins, and in this review, we discuss the involvement of melatonin and CaBP-9k with respect to calcium homeostasis and apoptotic cell death. In future studies, we hope to provide important information on the roles played by CaBP-9k in cell signal transduction, cell proliferation, and $Ca^{2+}$ homeostasis in vivo and in vitro.

• Molecules and Cells
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• 제22권3호
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• pp.285-290
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• 2006

The light sensing system in the eye directly affects the circadian oscillator in the mammalian suprachiasmatic nucleus (SCN). To investigate this relationship in the rat, we examined the circadian expression of clock genes in the SCN and eye tissue during a 24 h day/night cycle. In the SCN, rPer1 and rPer2 mRNAs were expressed in a clear circadian rhythm like rCry1 and rCry2 mRNAs, whereas the level of BMAL1 and CLOCK mRNAs decreased during the day and increased during the night with a relatively low amplitude. It seems that the clock genes of the SCN may function in response to a master clock oscillation in the rat. In the eye, the rCry1 and rCry2 were expressed in a circadian rhythm with an increase during subjective day and a decrease during subjective night. However, the expression of Opn4 mRNA did not exhibit a clear circadian pattern, although its expression was higher in daytime than at night. This suggests that cryptochromes located in the eye, rather than melanopsin, are the major photoreceptive system for synchronizing the circadian rhythm of the SCN in the rat.

• Journal of Photoscience
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• 제9권2호
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• pp.5-8
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• 2002

Photoperiodism is an important adaptive phenomenon in various physiological parameters including reproduction to cope with seasonal changes. Involvement of extraretinal photoreceptors in the photoperiodism in non-mammalian vertebrates has been well established. In addition, circadian clock system is known to be involved in the photoperiodic time measurement. The pathway consists of light-input system, time measurement system (circadian clock), gonadotropin releasing hormone (GnRH) production in the hypothalamus, luteinizing hormone (LH) and follicle stimulating hormone (FSH) production in the pituitary, and final gonadal development. Recently, several laboratories reported photopigments newly cloned in the pineal, eyes and deep brain in addition to already known visual pigments in the retina. These are pinopsin, parapinopsin, VA-opsin, melanopsin, etc. All these photopigments belong to the opsin family having retinal as the chromophore. However, the function of these photopigments remains unknown. I reviewed the studies on the location of the photopigments by immunocytochemistry. I also discussed the results on the action spectra for induction of gonadal development in relation with the location of the photoreceptors. Various physiologically active substances distribute in the vertebrate brain. Such substances are GnRH, GnIH, neuropeptide Y, vasoactive intestinal peptide, c-Fos, galanin, neurosteroids, etc. I summarized the immunhistochemical studies on the distribution and the photoperiodic changes of these substances and discussed the route from the deep brain photoreceptor to GnRH cells.