Effects Of Pınealectomy On Morphologıcal Features Of Blood Vessel In Chıcken: An Electron Mıcroscopıc And Stereologıcal Study

Abstract

Although the effects of melatonin on vascular smooth muscle and vascular reactivity are described in last decade, the effects of melatonin on vascular tissues are still vague. The current study investigated the effects of pinealectomy on the blood vessel wall in the chicken. Fifteen chicks were divided into three groups, namely unoperated control, sham-operated and pinealectomized chicks. At the end of the experiment, a quantitative structural analysis of 15 sciatic artery samples from these groups was investigated. Effects of pinealectomy were quantified using volume fraction approach of stereological method. In this study, total cross-sectional area of the artery in pinealectomy group was significantly higher than those in unoperated control and sham-operated animals (p < 0.05). However, surgical pinealectomy procedure resulted in a significantly decreased thickness of the tunica adventitia of the vessel wall, in contrast to those of tunica media (p < 0.01). The present results indicate that pinealectomy had a vasodilator effect on the sciatic artery. In the light of current study, the structural changes in the vessel demonstrated by quantitative morphometric methods have been interpreted as a reflection of the role of melatonin on vessel wall and vascular reactivity, but this suggestion need to be validated in the human setting.

Keywords

• Artery
• Chicken
• Electron microscopy
• Stereology
• Pinealectomy
• Melatonin

References

1. Anwar, M.M., Meki, A.R., Rahma, H.H. 2001. Inhibitory effects of melatonin on vascular reactivity: possible role of vasoactive mediators. Comp. Biochem. Physiol. C. Toxicol. Pharmacol. 130, 357-367.
2. Chucharoen, P., Chetsawang, B., Srikiatkhachorn, A., Govitrapong, P. 2003. Melatonin receptor expression in rat cerebral artery. Neurosci. Lett. 341, 259-261.
3. Cuzzocrea, S., Costantino, G., Mazzon, E., Micali, A., De Sarro, A., Caputi, A.P. 2000. Beneficial effects of melatonin in a rat model of splanchnic artery occlusion and reperfusion. J. Pineal Res. 28, 52-63.
4. Doolen, S., Krause, D.N., Dubocovich, M.L., Duckles, S.P. 1998. Melatonin mediates two distinct responses in vascular smooth muscle. Eur. J. Pharmacol. 345, 67-69.
5. Ekmekcioglu, C., Haslmayer, P., Phillips, C., Mehrabi, M.R., Glogar, H.D., Grimm, M., Thalhammer, T., Marktl, W. 2001. 24h variation in the expression of the mt1 melatonin receptor subtype in coronary arteries derived from patients with coronary heart disease. Chronobiol. Int. 18, 973-985.
6. Geary, G.G., Duckles, S.P., Krause, D.N. 1998. Effect of melatonin in the rat tail artery: role of K+ channels and endothelial factors. Br. J. Pharmacol. 123, 1533-1540.
7. Gundersen, H.J.G. 1986. Stereology of arbitrary particles. A review of unbiased number and size estimators and the presentation of some new ones, in memory of William R. Thompson. J. Microsc. 143, 3-45.
8. Hadju, M.A., Heistad, D.D., Siems, J.E., Baumbach, G.L. 1990. Effects of aging on mechanics and composition of cerebral arterioles in rats. Circ. Res. 66, 1747-1754.

9. Joo, J.Y., Uz, T., Manev, H. 1998. Opposite effects of pinealectomy and melatonin administration on brain damage following cerebral focal ischemia in rat. Restor Neurol Neurosci. 13, 185-191.
10. Kaplan, S., Canan, S., Aslan, H., Ünal, B., Şahin, B. 2001. A simple technique to measure the movements of the microscope stage along the x and y axes for stereological methods. J. Microsc. 203, 321-325.
11. Kaplan, S., Gokyar, A., Unal, B., Tunç, A.T., Bahadır, A., Aslan, H. 2005. A simple technique for localizing consecutive fields for disector pairs in light microscopy: Application to neuron counting in rabbit spinal cord following spinal cord injury. J. Neurosci. Methods. 145, 277-284.
12. Laitinen, J.T, Viswanathan, M., Vakkuri, O., Saavedra, J.M. 1992. Differential regulation of the rat melatonin receptors: selective age-associated decline and lack of melatonin-induced changes. Endocrinology. 130, 2139-2144.
13. Mahle, C.D., Goggins, G.D., Agarwal, P., Ryan, E., Watson, A.J. 1997. Melatonin modulates vascular smooth muscle tone. J. Biol. Rhythms. 12, 690-696.
14. Masana, M.I., Doolen, S., Ersahin, C., Al-Ghoul, W.M., Duckles, S.P., Dubovich, M.L., Krause, D.N. 2002. MT(2) melatonin receptors are present and functional in rat caudal artery. J. Pharmacol. Exp. Ther. 302, 1295-1302.
15. Mishima, K., Okawa, M., Shimizu, T., Hishikawa, Y. 2001. Diminished melatonin secretion in the elderly caused by insufficient environmental illumination. J. Clin. Endocrinol Metab. 86, 129-134.
16. Monroe, K.K., Watts, S.W. 1998. The vascular reactivity of melatonin. Gen. Pharmacol. 30, 31-35.
17. Muck, A.O., Seeger, H., Bartsch, C., Lippert, T.H. 1996. Does melatonin affect calcium influx in human aortic smooth muscle cells and estradiol-mediated calcium antagonism? J. Pineal. Res. 20, 145-147.
18. Okatani, Y., Wakatsuki, A., Reiter, R.J. 2001a. Melatonin suppresses homocysteine enhancement of serotonin-induced vasoconstriction in the human umbilical artery. J. Pineal. Res. 31, 242-247.
19. Okatani, Y., Wakatsuki, A., Watanabe, K., Taniguchi, K., Fukaya, T. 2001b. Weak vasoconstrictor activity of melatonin in human umbilical artery: relation to nitric oxide-scavenging action. Eur. J. Pharmacol. 417, 125-129.
20. O’Rourke, S.T., Hammad, H., Delagrange, P., Scalbert, E., Vanhoutte, P.M. 2003. Melatonin inhibits nitrate tolerance in isolated coronary arteries. Br. J. Pharmacol. 139, 1326-1332.
21. Pache, M., Krauchi, K., Haefliger, I.O., Wirz-Justice, A., Flammer, J., Meyer, P. 2002. Effect of melatonin on vascular responses of porcine ciliary arteries. Curr Eye Res. 24, 313-317.
22. Pei, Z., Fung, P.C., Cheung, R.T. 2003. Melatonin reduces nitric oxide level during ischemia but not blood-brain barrier breakdown during reperfusion in a rat middle cerebral artery occlusion stroke model. J. Pineal. Res.34,110-118.
23. Pogan, L., Bissonnette, P., Parent, L., Sauve, R. 2002. The effects of melatonin on Ca(2+) homeostasis in endothelial cells. J. Pineal. Res. 33, 37-47.
24. Regrigny, O., Delagrange, P., Scalbert, E., Lartaud-Idjouadiene, I., Atkinson, J., Chillon, J.M. 1999. Effects of melatonin on rat pial arteriolar diameter in vivo. Br. J. Pharmacol. 127, 1666-1670.
25. Regrigny, O., Dupuis, F., Atkinson, J., Liminana, P., Scalbert, E., Delagrange, P., Chillon, J.M. 2001. Cerebral arteriolar structure and function in pinealectomized rats. Am. J. Physiol. Heart Circ. Physiol. 281, H1476-1480.
26. Sack, R.L., Lewy, A.J., Erb, D.L., Vollner, W.M., Singer, C.M. 1986. Human melatonin production decreases with age. J. Pineal. Res. 3, 379-388.
27. Schmitz, C. 1998. Variation of fractionator estimates and its prediction. Anat Embryol. 198, 371-397.
28. Schmitz, C, Hof PR. 2000. Recommendations for straightforward and rigorous methods of counting neurons based on a computer simulation approach. J. Chem Neuroanat. 20, 93-114.
29. Shibata, S., Satake, N., Takagi, T., Usui, H. 1989. Vasorelaxing action of melatonin in rabbit basilar artery. Gen. Pharmacol. 20, 677-680.
30. Sun, F.Y., Lin, X., Mao, L.Z., Ge, W.H., Zhang, L.M., Huang, Y.L., Gu, J. 2002. Neuroprotection by melatonin against ischemic neuronal injury associated with modulation of DNA damage and repair in the rat following a transient cerebral ischemia. J. Pineal. Res. 33, 48-56.
31. Turgut, M., Yenisey, C., Uysal, A., Bozkurt, M., Yurtseven, M.E. 2003. The effects of pineal gland transplantation on the production of spinal deformity and serum melatonin level following pinealectomy in the chicken. Eur. Spine J. 12, 487-494.
32. Vandeputte, C., Giummelly, P., Atkinson, J., Delagrange, P., Scalbert, E., Capdeville-Atkinson, C. 2001. Melatonin potentiates NE-induced vasoconstriction without augmenting cytosolic calcium concentration. Am. J. Physiol. Heart Circ. Physiol. 280, H420-425.
33. Viswanathan, M., Laitinen, J.T., Saavedra, J.M. 1993. Vascular melatonin receptors. Biol. Signals. 2, 221-227.
34. Weekley, L.B. 1995. Pharmacologic studies on the mechanism of melatonin-induced vasorelaxation in rat aorta. J. Pineal. Res. 19, 133-138.
35. West, M.J., Slomianka, L., Gundersen, H.J.G. 1991. Unbiased stereological estimation of the total number of neurons in the subdivisions of the rat hippocampus using the optical fractionator. Anat. Rec. 231, 482-497.