RESUMEN
When young rats are exposed to white fluorescent light the concentration of calcium in their serum decreases. This effect is prevented by shielding the occiput, by inhibiting corticosterone synthesis, and by exogenous melatonin. Furthermore, the expected hypocalcemic response to cortisol injection is prevented by melatonin. Light-induced hypocalcemia may result from increased calcium uptake by bone when the blocking effect of melatonin decreases after pineal inhibition by transcranial illumination.
Asunto(s)
Animales Recién Nacidos/efectos de la radiación , Hipocalcemia/prevención & control , Melatonina/farmacología , Animales , Modelos Animales de Enfermedad , Femenino , Humanos , Hidrocortisona/antagonistas & inhibidores , Hipocalcemia/etiología , Recién Nacido , Ictericia Neonatal/terapia , Luz , Masculino , Fototerapia/efectos adversos , Ratas , Análisis Espectral , Factores de TiempoRESUMEN
As part of a long-term study of the effects of irradiation during development, prenatal and early neonatal mortality were evaluated for beagles exposed in utero at 8 days postcoitus (dpc), 28 dpc, 55 dpc, or 2 days postpartum. Mean doses used were 0,0.16, or 0.83 Gy. A decrease in whelping rates was observed for female breeders irradiated at 8 dpc. There was a significant decrease in litter sizes from female breeders irradiated at 8 and 28 dpc. Both of these findings are indicative of increased embryonic mortality. There was a significant decrease in the percentage of females born after exposures given at 28 dpc, indicating a differential radiosensitivity by sex. A significant increase in early neonatal mortality up to 14 days of age was observed for beagles exposed 8 or 28 dpc, again with an excess mortality in females.
Asunto(s)
Animales Recién Nacidos/efectos de la radiación , Desarrollo Embrionario y Fetal/efectos de la radiación , Muerte Fetal/etiología , Efectos Tardíos de la Exposición Prenatal , Animales , Animales Recién Nacidos/crecimiento & desarrollo , Radioisótopos de Cobalto , Perros , Femenino , Física Sanitaria , Tamaño de la Camada/efectos de la radiación , Masculino , Embarazo , Factores Sexuales , Estadística como Asunto , Irradiación Corporal TotalRESUMEN
The fertility span between the first and the last estrus was compared among female Chinese hamsters exposed to 1 Gy X-rays on neonatal day 0, 2, 4, 6, 8, 10 and 14. The fertility span changed dramatically according to the age at the time of irradiation. The females irradiated on day 4, 6 and 8 showed a definite delay in sexual maturation and a very early cessation of the estrous cycles, while those irradiated on day 10, 2 and 14 (in this order) showed a much longer, nevertheless significantly shortened, fertility span. Reduction in the number of juvenile oocytes by acute killing was responsible for this shortened reproductive life. The present study indicated again that the sensitivity of the oocytes to the lethal effects of X-rays is unquestionably meiotic stage-dependent.