Long-term melatonin administration attenuates low-LET gamma-radiation-induced lymphatic tissue injury during the reproductively active and inactive phases of Indian palm squirrels (Funambulus pennanti).
A comparative analysis of low linear energy transfer (LET) gamma-radiation-induced damage in the lymphatic tissue of a tropical seasonal breeder, Indian palm squirrel (Funambulus pennanti), during its reproductively active phase (RAP) and inactive phase (RIP) was performed with simultaneous investigation of the effects of long-term melatonin pre-treatment (100 microg/100 g body weight). A total of 120 squirrels (60 during RAP and 60 during RIP) were divided into 12 groups and sacrificed at 4, 24, 48, 72 and 168 h following 5 Gy gamma-radiation exposure; control groups were excluded from exposure. Total leukocyte count and absolute lymphocyte count (ALC) and melatonin only of peripheral blood, stimulation index, thiobarbituric-acid-reactive substances (TBARS) level, superoxide dismutase (SOD) activity, and the apoptotic index of spleen as analysed by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labelling (TUNEL) noted at observed time-points were significantly reduced in melatonin pre-treated groups during RAP and RIP. Long-term melatonin pre-treatment mitigated radiation-induced alterations more prominently during RIP, as assessed by ALC, TBARS, SOD, TUNEL and caspase-3 activity, at some time-points. Our results demonstrate an inhibitory role of melatonin on caspase-3 activity in splenocytes during RAP and RIP following gamma-radiation-induced caspase-mediated apoptosis. Hence, we propose that melatonin might preserve the viability of immune cells of a seasonal breeder against background radiation, which is constantly present in the environment.
Pineal Research Laboratory, Department of Zoology, Banaras Hindu University, Varanasi-221005, India.
S
S
Sharma
C
C
Haldar
S K
SK
Chaube
T
T
Laxmi
S S
SS
Singh
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D053148:Caspase 3 / Q000378:metabolism; D002940:Circadian Rhythm / Q000276:immunology; D053938:DNA Fragmentation; D005720:Gamma Rays / Q000009:adverse effects*; D007958:Leukocyte Count; D018499:Linear Energy Transfer; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D008221:Lymphoid Tissue / Q000187:drug effects / Q000528:radiation effects*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects; D011833:Radiation Injuries, Experimental / Q000517:prevention & control*; D012062:Relative Biological Effectiveness; D012098:Reproduction / Q000276:immunology / Q000502:physiology*; D012589:Sciuridae / Q000276:immunology / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects; D013154:Spleen / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D017392:Thiobarbituric Acid Reactive Substances; D013482:Superoxide Dismutase; D053148:Caspase 3; D008550:Melatonin