ABSTRACT
BACKGROUND@#Exposure to the ionizing radiation (IR) encountered outside the magnetic field of the Earth poses a persistent threat to the reproductive functions of astronauts. The potential effects of space IR on the circadian rhythms of male reproductive functions have not been well characterized so far.@*METHODS@#Here, we investigated the circadian effects of IR exposure (3 Gy X-rays) on reproductive functional markers in mouse testicular tissue and epididymis at regular intervals over a 24-h day. For each animal, epididymis was tested for sperm motility, and the testis tissue was used for daily sperm production (DSP), testosterone levels, and activities of testicular enzymes (glucose-6-phosphate dehydrogenase (G6PDH), sorbitol dehydrogenase (SDH), lactic dehydrogenase (LDH), and acid phosphatase (ACP)), and the clock genes mRNA expression such as Clock, Bmal1, Ror-α, Ror-β, or Ror-γ.@*RESULTS@#Mice exposed to IR exhibited a disruption in circadian rhythms of reproductive markers, as indicated by decreased sperm motility, increased daily sperm production (DSP), and reduced activities of testis enzymes such as G6PDH, SDH, LDH, and ACP. Moreover, IR exposure also decreased mRNA expression of five clock genes (Clock, Bmal1, Ror-α, Ror-β, or Ror-γ) in testis, with alteration in the rhythm parameters.@*CONCLUSION@#These findings suggested potential health effects of IR exposure on reproductive functions of male astronauts, in terms of both the daily overall level as well as the circadian rhythmicity.
Subject(s)
Animals , Male , Mice , ARNTL Transcription Factors/genetics , Acid Phosphatase , CLOCK Proteins/genetics , Circadian Rhythm/radiation effects , Epididymis/radiation effects , Gene Expression/radiation effects , Genitalia, Male/radiation effects , Glucosephosphate Dehydrogenase , L-Iditol 2-Dehydrogenase , L-Lactate Dehydrogenase , Mice, Inbred C57BL , Models, Animal , Nuclear Receptor Subfamily 1, Group F, Member 1/genetics , Nuclear Receptor Subfamily 1, Group F, Member 2/genetics , Nuclear Receptor Subfamily 1, Group F, Member 3/genetics , RNA, Messenger/genetics , Radiation Exposure , Radiation, Ionizing , Reproductive Physiological Phenomena/radiation effects , Sperm Motility/radiation effects , Spermatozoa/radiation effects , Testis/radiation effectsABSTRACT
Objective: Autism is a neurodevelopmental disorder characterized by difficulty in verbal and non-verbal communication, impaired social interaction, and restricted and repetitive behavior. It has been recently introduced as a multigenic disorder with significant epigenetic effects on its pathology. Recently, epigenetic silencing of retinoic acid receptor-related orphan receptor alpha [ROR alpha] gene [which has an essential role in neural tissue development] was shown to have occurred in autistic children due to methylation of its promoter region. This may thus explain a significant part of the molecular pathogenesis of autism. Therefore, we aimed to confirm this finding by implementing a case-control [experimental] study in the population of Isfahan
Materials and Methods: The methylation status of a 136 bp sequence of a GpG island [encompassing 13 CpG sites] in the RORA promoter region [positions -200 to -64] as an experimental study was examined in the lymphocyte cells of 30 autistic children after sodium bisulfite treatment using the melting curve analysis-methylation [MCA-Meth] assay compared with normal children. Also, quantitative reverse transcriptase-polymerase chain reaction [qRT-PCR] analysis was used to estimate the level of mRNA transcripts and to evaluate MCA-Meth analysis results
Results: This study revealed no methylation in the examined promoter regions in both autistic and normal children, with the melting curve of all studied samples being comparable to that of the non-methylated control. The results of MCA-Meth analysis were also consistent with qRT-PCR results. We therefore observed no significant difference in the levels of ROR alpha transcripts in the blood lymphocytes between autistic and healthy children
Conclusion: The methylation of the RORA promoter region may not be considered as a common epigenetic risk factor for autism in all populations. Hence, the molecular pathogenesis of autism remains unclear in the population investigated