Sema USLU, İmer OKAR, Emine SUNAL, Erinç ARAL, Eker Ayla SARIBOYACI, Ertunç ARAL

Response of the pineal gland in rats exposed to three different light spectra of short periods

Epifiz, foto-endokrin sistemin bir parçasıdır. Foton enerjisi bu sistemin fonksiyonu üzerinde çok önemlidir ve günlük melatonin üretimini etkiler. Memelilerde melatonin üretimi ışığın şiddeti ve dalga boyu etkisindedir. Yapılan bu çalışmada erkek Sprague-Dawley türü sıçanlarda kısa fotoperiotta (kış dönemi) ve sabit ışık şiddetinde üç farklı dalga boyunun, uzun süre kullanımda epifiz üzerindeki etkisi araştırılmıştır. Hayvanlar beş gruba ayrılarak 8 saat aydınlık ve 16 saat karanlık olmak üzere ışığı ve ısısı otomatik olarak ayarlanan odalarda büyütülmüşlerdir. Dalga boyları için Lee filtreler kullanılmıştır. Altı aylık yaşa ulaşan hayvanlardan karanlık periyodun 3. saatinde 3 lükslük kırmızı ışık altında bir hafta süre ile kan örnekleri alınmıştır. Kandaki melatonin miktarları ELISA metoduyla ölçülmüştür. Epifizler elektron mikroskobik gözlemler için hazırlanmıştır. Sonuçlarımızda kandaki melatonin değerleri, mavi dalga boyu uygulanan grupta ve kontrol grubunda diğer gruplara oranla yüksek bulunmuştur. Bu nedenle sıçanlarda melatonin üretimi üzerine mavi dalga boyu etkisinin diğer dalga boylarına göre daha fazla olduğunu düşünmekteyiz.

Kısa fotoperiyodda üç farklı ışık dalga boyuna maruz bırakılmış sıçanlarda epifiz yanıtı

The pineal gland is a part of the photo-endocrine system. Photon energy is important for the function of this system, and affects the level of nocturnal melatonin. In mammals light-induced suppression of melatonin production is dependent on the intensity and wavelength of the light used. We studied the chronic effects of light wavelengths on the pineal gland in rats after exposure to a short photoperiod using 3 different light spectra with the same irradiance. Male Sprague-Dawley rats were used. The animals were divided into 5 groups. They were exposed 8/16 L:D periods in rooms under automatically regulated light and climate. Lee filters were used for the light spectra application. From animals at the age of 6 months blood samples were taken over a week at the third hour of the dark period under dim red light. The pineal glands were processed for electron microscopy. Melatonin levels in the blood were analyzed by ELISA. Melatonin levels were the higher in control group and group 5 (blue light spectra) compared to the others. We demonstrated that blue light spectra have a greater effect on melatonin production in rats.

PDF

___

1. Kappers, J. A.: The mammalian pineal gland a survey. Acta Neu- 9. rochir., 1976; 34: 109-149.
2. Reither, R.J., Robinson, J.O.: Melatonin (Your Body's Natural 10. Wonder Drug). New York: Bantham Books, 1995; 3-146.
3. Reither, R.J.: The Pineal Gland (Anatomy and Biochemistry). 11. Chapter 5, 6, Florida: CRC Press, INC. Baco Raton. 1981; 1: 122- 169 . 4. lllnerova, H.: Entrapment of mammalian circadian rhythms in melatonin production by light. Pineal Res. Rev., 1988; 6: 173- 217.
5. Cassone, V.M.: Effects of melatonin on vertebrate circadian systems. Trends Neurosci., 1990; 13: 457-464.
6.Cassone, V.M., Warren, W.S., Brooks, D.S, Lu, J.: Melatonin, the pineal gland and circadian rhythms. J. Biol. Rhythms, 1993; 8 Suppl: S73-81.
7.Honma, S., Kanematsu, N., Katsuno, Y., Honma, K.: Light supression of nocturnal pineal and plasma melatonin in rats depends on wavelength and time of day. Neurosci. Lett, 1992; 147: 201-204
8.Underwood, H., Goldman, B.D.: Vertebrate circadian and photoperiodic systems. Role of the pineal and melatonin. J. Biol. Rhythms., 1987; 2: 279-315.
9. Szel, A., Rohlich, P.: The cone types of retina detected by antivisual pigment antibodies. Exp. Eye Res., 1992; 55: 47-52.
10. Reiter, R.J.: Neuroendocrine effects of light. Int. J. Biometeorol., 1991; 35: 169-175.
11. Brainard, G.C., Vaughan, M.K. Reiter, R.J.: Effect of light irradi-ance and wavelength on the Syrian hamster reproductive system. Endocrinology, 1986; 119:648-654.
12. Vaughan, M.K., Brainard, G.C., Reiter, R.J.: Photoperiodic and light spectral conditions which inhibit circulating concentrations of thyroxine in the male hamster. Life Sci., 1985; 36: 2183-2188.
13. Jarmak, A., Zawilska, J.B., Nowak, J.: Effect of light with various wavelengths and impulse times on nocturnal suppression of n-acetyltransferase activation by serotonin in the chick. Klin. Oczna., 1996; 98: 417-422.
14.Sinhasane, S.V., Joshi, B.N.: Exposure to different spectra of light continuous light and treatment with melatonin affect reproduction in the Indian desert gerbil Meriones hurrianae (Jerdon). Biol. Signals Recept, 1998; 7: 179-187.
15. Brainard, G.C., Richardson, B.A., King, T.S. Reiter, R.J.: The influence of different light spectra on the suppression of pineal melatonin content in the Syrian hamster. Brain Res., 1984; 294: 333-339
16. Bertoni, J.M., Sprenkle, P.M., Brainard, G.C.: Effects of different light wavelengths at equal irradiance on testis weight, protein content, and k-paranitrophenylphosphates activity in the Syrian hamster. Life Sci., 1987; 40: 1479-1486.
17. Chenigi, S., Hofmann, B.E., Kaider, A.: Direct enzyme-linked immunosorbent assay and a radioimmunoassay for melatonin compared. Clin. Chem., 1995; 41 :381-386.
18. Dominguez, S., Piezzi, R.S., Scardapane, L, Guzman, J.A.: A light and electron microscopic study of the pineal gland of the viscacha (Lagostomus maximus maximus) J. Pineal Res., 1987; 4: 211-219.
19. Calvo, J., Boya J.: infrastructure of the pineal gland in the adult rat. J. Anat, 1984; 138: 405-409.
20. Bhatnagar, K.P.: The ultrastructure of mammalian pinealocytes: A systematic investigation. Microsc. Res. Tech., 1992; 21: 85-115.
21. Becker, U.G., Vollrath, L: 24 hour-variations of pineal gland volume, pinealocyte nuclear volume and mitotic activity in male Spraque-Dawley rats. J. Neural Transm., 1983; 56: 211-221.
22. Cardinali, D.P., Larin, F., Wurtman, J.R.: Control of the rat pineal gland by light spectra. Proc. Natl. Acad. Sci. USA., 1972; 69: 2003-2005.
23. Karasek, M., Marek, K., Pevet, P.: Influence of a short light pulse at night on the ultrastructure of the rat pinealocytes: a quantitative study. Cell Tissue Res., 1988; 254: 247-249.
24. Thiele; G., Holtorf, A., Steinlechner, S. Reiter, R.J.: The influence of different light irradiance on pineal N-acetyltransferase activity and melatonin levels in the cotton rat, Sigmodon hispidus. Life Sci., 1983; 33: 1543-1547.
25. van-Benthem, J., Steinen, A.C., Sommer, M.C., De Koning, J., Ebels I., Balemans M.G.: The influence of light of different wavelengths on the methylating capacity of the pineal gland of male golden hamsters in relation to reproduction. J. Neural Transm., 1989:78:145-158.
26. Poeggeler, B.H., Barlow-Walden, L.R., Reiter, R.J., Saarela, S., Menendez-Pelaez, A., Yaga, K., Manchester, L.C., Chen, L.D., Tan, D.X.: Red-light-induced suppression of melatonin synthesis is mediated by n-methyl-d-aspartate receptor activation in retinally normal and retinally degenerate rats. J. Neurobiol., 1995; 28:1-8.
27. Karasek, M., Stankov, B., Lucini, V., Scaglione, F., Esposti, G., Mariani, M., Fraschini, F.: Comparison of the rat pinealocyte ultrastructure with melatonin concentrations during daytime and at night. J. Pineal Res., 1990; 9: 251-257.
28. Csernus, V., Becher, P., Mess, B.: Wavelength dependency of light-induced changes in rhythmic melatonin secretion from chicken pineal gland in vitro. Neuro Endocrinol. Lett, 1999; 20: 299-304.
29. Brainard, G.C., Hanifin, J.P., Greeson, J.M., Byrne, B., Glickman, G., Gerner, E., Rollag, M.D.: Action spectrum for melatonin regulation in humans. J. Neurosci., 2001; 21: 6405-6412.
30. Thapan, K., Arendt, J., Skene, D.J.: An action spectrum for melatonin suppression: evidence for a novel non-rod, non-cone photoreceptor system in humans. J. Physiol., 2001; 535: 261-267.