The Changes of Pineal Function in Fractionally Irradiated Rats

Ahlersová, E; Pástorová, B; Kassayová, Monika; Ahlers, I; Smajda, B

doi:10.1007/978-94-011-4585-5_52

Cited by 5 publications

(6 citation statements)

References 5 publications

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“…Our finding of a reduced melatonin secretion in brain tumour survivors who had received radiotherapy to midline brain structures is supported by animal experimental work demonstrating that irradiation reduces melatonin biosynthesis in the pineal gland in rats. 34 Yet, although the hormone undoubtedly plays a role in the mammalian sleep-wake cycle 7 and small preliminary studies have found an association between a history of radiotherapy, sleep disturbances and reduced salivary 19 or plasma 21 melatonin levels, we were not able to show a direct effect of low aMT6s excretion on subjective sleep parameters. In the complex system of human sleep and the sleep-wake cycle, disturbances are almost always multifactorial and a lack of pineal melatonin as one of many factors might not weigh in as heavily as we had expected.…”

Section: Discussioncontrasting

confidence: 63%

Melatonin secretion following brain midline irradiation is diminished, but not correlated with subjective sleep disturbances

Rosenkranz

Thissen

Siegel

et al. 2018

Clinical Endocrinology

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Our data suggest that radiation exposure to the pineal gland negatively affects melatonin secretion. This lack of pineal melatonin does not influence subjective sleep quality. As melatonin has important antioxidant and cancer-protective effects, further research is necessary to elucidate whether these patients have an increased risk of developing secondary neoplasms and other radiation late effects.

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Section: Discussioncontrasting

confidence: 63%

Melatonin secretion following brain midline irradiation is diminished, but not correlated with subjective sleep disturbances

Rosenkranz

Thissen

Siegel

et al. 2018

Clinical Endocrinology

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“…This finding suggests that various insults, such as genotoxic stress and perhaps chemical exposure among others, may likewise propagate a decline in melatonin levels. Ahlersova et al . (1998) similarly observed a reduction in pineal and circulating melatonin in rats repeatedly exposed to increasing dosages of IR and attributed these effects to changes in key enzymes involved in melatonin synthesis and/or the metabolism of its precursor, serotonin.…”

Section: Discussionmentioning

confidence: 99%

Differential effects of genotoxic stress on both concurrent body growth and gradual senescence in the adult zebrafish

et al. 2007

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SummaryAmong vertebrates, fish and mammals show intriguing differences in their growth control properties with age. The potential for unlimited or indeterminate growth in a variety of fish species has prompted many questions regarding the senescent phenomena that appear during the aging process in these animals. Using zebrafish as our model system, we have attempted in our current study to examine the growth phenomena in fish in relation to the onset of senescence-associated symptoms, and to evaluate the effects of genotoxic stress on these processes. We observed in the course of these analyses that the zebrafish undergoes continuous growth, irrespective of age, past the point of sexual maturation with gradually decreasing growth rates at later stages. Animal population density, current body size and chronological age also play predominant roles in regulating zebrafish growth and all inversely influence the growth rate. Interestingly, the induction of genotoxic stress by exposure to ionizing radiation (IR) did not adversely affect this body growth ability in zebrafish. However, IR was found to chronically debilitate the regeneration of amputated caudal fins and thereby induce high levels of abnormal fin regeneration in the adult zebrafish. In addition, by resembling and mimicking the natural course of aging, IR treatments likewise enhanced several other symptoms of senescence, such as a decline in reproductive abilities, increased senescenceassociated β β β β -galactosidase activity and a reduction in melatonin secretion. Our current data thus suggest that during the lifespan of zebrafish, the onset of senescenceassociated symptoms occurs in parallel with continuous growth throughout mid-adulthood. Moreover, our present findings indicate that genotoxic DNA damage may play a role as a rate-limiting factor during the induction of senescence, but not in the inhibition of continuous, density-dependent growth in adult zebrafish.

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“…It has been reported that at a dose of 14.4 Gy TB irradiation causes a significant decrease in the serum and pineal levels of melatonin 30 min to 6 h post-exposure in rats (16), but in the rats irradiated up to total doses of 4.8 and 9.6 Gy melatonin levels are not significantly different from control values (16). The pineal gland is not in the region directly influenced in AP-irradiated rats and endogenous melatonin level is not influ-…”

Section: Discussionmentioning

confidence: 99%

“…Plasma levels of melatonin exhibit a circadian variation, with the highest concentrations occurring at night and lower levels during the day (16). Light exposure suppresses melatonin secretion (17).…”

Section: Introductionmentioning

confidence: 99%

Melatonin prevents inflammation and oxidative stress caused by abdominopelvic and total body irradiation of rat small intestine

Güney

Hiçsönmez

Uluoğlu

et al. 2007

Braz J Med Biol Res

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We investigated the day-night differences in intestinal oxidativeinjury and the inflammatory response following total body (TB) or abdominopelvic (AP) irradiation, and the influence of melatonin administration on tissue injury induced by radiation. Rats (male Wistar, weighing 220-280 g) in the irradiated groups were exposed to a dose of 8 Gy to the TB or AP region in the morning (resting period -1 h after light onset) or evening (activity span -13 h after light onset). Vehicle or melatonin was administered immediately before, immediately after and 24 h after irradiation (10, 2.0 and 10 mg/kg, ip, respectively) to the irradiated rats. AP (P < 0.05) and TB (P < 0.05) irradiation applied in the morning caused a significant increase in thiobarbituric acid reactive substance (TBARS) levels. Melatonin treatment in the morning (P < 0.05) or evening (P < 0.05) decreased TBARS levels after TB irradiation. After AP irradiation, melatonin treatment only in the morning caused a significant decrease in TBARS levels (P < 0.05). Although we have confirmed the development of inflammation after radiotherapy by histological findings, neither AP nor TB irradiation caused any marked changes in myeloperoxidase activity in the morning or evening. Our results indicate that oxidative damage is more prominent in rats receiving TB and AP irradiation in the morning and melatonin appears to have beneficial effects on oxidative damage irrespective of the time of administration. Increased neutrophil accumulation indicates that melatonin administration exerts a protective effect on AP irradiation-induced tissue oxidative injury, especially in the morning.

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The Changes of Pineal Function in Fractionally Irradiated Rats

Cited by 5 publications

References 5 publications

Melatonin secretion following brain midline irradiation is diminished, but not correlated with subjective sleep disturbances

Melatonin secretion following brain midline irradiation is diminished, but not correlated with subjective sleep disturbances

Differential effects of genotoxic stress on both concurrent body growth and gradual senescence in the adult zebrafish

Melatonin prevents inflammation and oxidative stress caused by abdominopelvic and total body irradiation of rat small intestine

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