Circadian rhythmicity of the activity of hydroxyindole-o-methyl transferase (HIOMT) in the formation of melatonin and 5-methoxytryptophol in the pineal, retina, and harderian gland of the golden hamster

Abstract

The day and night rhythms in the activity of HIOMT in the formation of melatonin of 5-methoxytryptophol have been determined in the pineal, retina and Harderian gland of the adult male golden hamster. In all hamsters used there was no detectable HIOMT activity in the deep pineal. In the superficial pineal HIOMT activity, involved in the synthesis of melatonin (Mel), was observed to be high at the end of the dark period and at the middle of the light period. Considering the HIOMT activity involved in the production of 5-methoxytryptophol (5-MTL), an increase in 5-MTL synthesis was observed only during the light period. Comparing the peak of Mel-production with that of 5-MTL it appears that during the light period the pineal produces more 5-MTL than Mel. In the Harderian glands, the circadian course of HIOMT activity involved in the synthesis of Mel seems to run parallel to that of the enzyme implicated in 5-MTL synthesis, both being stimulated at the end of the dark period. The activity of HIOMT in 5-MTL production is, however, always approximately 2 times higher than for Mel synthesis. In the retina the synthesis of Mel and 5-MTL is not significantly higher during the dark period than during the light period. However, the production of 5-MTL is larger than that of Mel. It appears that (1) with the exception of the end of the dark period, the extra-pineal synthesis of Mel and 5-MTL is always higher than that in the pineal; (2) the carcadian synthesis of 5-methoxyindoles is different in each organ, and (3) in the pineal the carcadian activity of HIOMT involved in 5-MTL formation is different from that of the same enzyme involved in the formation of Mel. The results are discussed.

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…The rat pineal HIOMT activity is between 0.7 and 2 nmol/mg protein/h (Sugden et al, 1987b;Ribelayga et al, 1997Ribelayga et al, , 1998bRibelayga et al, , 1999a. HIOMT activity has been measured in the retina and the Harderian gland, although at much lower levels (Quay, 1965;Cardinali and Rosner, 1971;Cardinali and Wurtman, 1972;Nagle et al, 1972Nagle et al, , 1973Pévet et al, 1980a;Wiechmann and Hollyfield, 1989;Bernard et al, 1995;Gauer and Craft, 1996;Djéridane et al, 1998;Ribelayga et al, 1998a). Enzyme studies suggest that the pineal and retina HIOMT are similar, but quite different from HIOMT in the Harderian gland (Cardinali and Wurtman, 1972).…”

“…Autocrine/Paracrine Effects. In addition to the pineal gland, MEL is synthesized in several other structures (retina, Harderian gland, gut) where the genetic expression and biochemical activity of the MEL-synthesizing enzymes have been detected (Quay, 1965;Cardinali and Wurtman, 1972;Quay and Ma, 1976;Brammer et al, 1978;Pévet et al, 1980a;Vivien-Roels et al, 1981;Gauer and Craft, 1996;Roseboom et al, 1996;Ribelayga et al, 1998a;Djéridane et al, 1998Djéridane et al, , 2000. Since following pinealectomy the plasma MEL concentration is very low and since some of these structures contain MEL-R (Dubocovich and Takahashi, 1987;Lopez-Gonzalez et al, 1991), it has been proposed that MEL plays an auto/paracrine role in these structures.…”

The influence of light of different wavelengths on the methylating capacity of the pineal gland of male golden hamsters in relation to reproduction

“…The pineals were quickly dissected, frozen in liquid nitrogen and stored at --80 ~ until determination. Because in the deep pineal neither HIOMT activity nor aMT content could be detected (P6vet et al, 1980;Sheridan and Rollag, 1983), only the superficial pineal gland was dissected. After dissection of the pineal gland, both testes were removed and weighed immediately.…”

Effects of Melatonin in Prevention of Neuropathy in STZ-Induced Diabetic Rats

“…Today many studies have focused on the beneficial effects of various antioxidants such as melatonin on diabetic neuropathy (Zangiabadi et al, 2007;Negi et al, 2010;Srinivasan et al, 2010). Melatonin is one of the tryptophan derivatives that is mainly synthesized in the pineal gland and also in retina, intestine, ovary, testis and bone marrow (Pevet et al, 1980;Gutierrez-Cuesta et al, 2007;Geoffriau et al, 1998). The physiologic importance of melatonin has not been recognized yet and its intervention in circadian rhythms has already been proposed as the most important function of this hormone.…”