title: Chronic melatonin administration mitigates behavioral dysfunction induced by γ-irradiation.
abstract: Melatonin, a 'hormone of darkness,' has been reported to play a role in a wide variety of physiological responses including reproduction, circadian homeostasis, sleep, retinal neuromodulation, and vasomotor responses. Our recent studies reported a prophylactic effect of exogenous melatonin against radiation-induced neurocognitive changes. However, there is no reported evidence for a mitigating effect of chronic melatonin administration against radiation-induced behavioral alterations. In the present study, C57BL/6 mice were given either whole day chronic melatonin administration (CMA) or chronic night-time melatonin administration (CNMA) by a low dose of melatonin in drinking water for a period of 2 weeks and 1 month following exposure to 6 Gy of γ-radiation. Various behavioral endpoints, such as locomotor activities, gross behavioral traits, basal anxiety level, and depressive tendencies were scored at different time points. Radiation exposure significantly impaired gross behavioral traits as observed in the open field exploratory paradigms and forced swim test. Both the CMA and CNMA significantly ameliorated the radiation-induced changes in exploratory tendencies, risk-taking behavior and gross behavior traits, such as rearing and grooming. Melatonin administration afforded anxiolytic function against radiation in terms of center exploration tendencies. The radiation-induced augmentation of immobility time in the forced swim test, indices of depression-like behavior was also inhibited by chronic melatonin administration. The results demonstrated the mitigating effect of chronic melatonin administration on radiation-induced affective disorders in mice.
authors.affiliation: NeuroBehavior Laboratory, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India.
authors.forename: Seenu
authors.initials: S
authors.lastname: Haridas
authors.forename: Mayank
authors.initials: M
authors.lastname: Kumar
authors.forename: Kailash
authors.initials: K
authors.lastname: Manda
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects / Q000528:radiation effects; D003866:Depressive Disorder / Q000209:etiology / Q000517:prevention & control; D004334:Drug Administration Schedule; D005720:Gamma Rays / Q000009:adverse effects*; D006120:Grooming / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000494:pharmacology; D001523:Mental Disorders / Q000209:etiology* / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D013550:Swimming / Q000523:psychology; D013997:Time Factors; D014916:Whole-Body Irradiation / Q000009:adverse effects
chemical_list: D014151:Anti-Anxiety Agents; D008550:Melatonin