RESUMEN
Zofran is a selective antagonist of 5-HT3 receptors which effectively prevents postradiation dyspeptic and behavioral disorders in dogs and rats. Administration of the drug normalizes intestinal absorption and propulsion activity in irradiated animals.
Asunto(s)
Ondansetrón/uso terapéutico , Traumatismos Experimentales por Radiación/prevención & control , Protectores contra Radiación/uso terapéutico , Antagonistas de la Serotonina/uso terapéutico , Animales , Perros , Relación Dosis-Respuesta en la Radiación , Evaluación Preclínica de Medicamentos , Femenino , Rayos gamma , Ácido Hidroxiindolacético/sangre , Ácido Hidroxiindolacético/efectos de la radiación , Masculino , Traumatismos Experimentales por Radiación/sangre , Traumatismos Experimentales por Radiación/complicaciones , Ratas , Serotonina/sangre , Serotonina/efectos de la radiación , Irradiación Corporal Total/efectos adversosRESUMEN
During the past decade, a number of reports indicated that the mammalian pineal gland is magnetosensitive in terms of spatial orientation. This indication is based on observations that artificial alterations of the direction of the earth's magnetic field (MF) markedly decreased the gland's capability to synthesize melatonin. These findings, however, seem paradoxical since animals as well as humans experience such alterations whenever they turn their heads. Therefore, the potential of the pineal for sensing magnetic fields was re-investigated. During the dark phase, rats were exposed to repeatedly inverted MFs, generated by two identical pairs of Helmholz coils; one pair connected to a power supply automatically, the other pair manually using an integrated potentiometer. Only the pineals of animals exposed to the automatically activated field responded with a reduced activity of the rate-limiting enzyme serotonin-N-acetyltransferase, lower melatonin levels and increases in serotonin and 5-hydroxyindole acetic acid. Hence, MF exposure itself did not affect the pineal. Rather, induced eddy currents in the animals, resulting from rapid On/Off transients of the artificially applied MF, are most likely the explanation.
Asunto(s)
Campos Electromagnéticos , Glándula Pineal/efectos de la radiación , Análisis de Varianza , Animales , Arilamina N-Acetiltransferasa/efectos de la radiación , Cromatografía Líquida de Alta Presión , Ácido Hidroxiindolacético/efectos de la radiación , Masculino , Melatonina/efectos de la radiación , Glándula Pineal/fisiología , Ratas , Ratas Endogámicas , Serotonina/efectos de la radiaciónRESUMEN
We exposed Macaca nemestrina (pig-tailed macaques) to electric (E) and magnetic (B) fields ranging in intensity from 3 kV/m and 0.1 G to 30 kV/m and 0.9 G for three 21-day (d) periods. Experimental animals were exposed to sham E and B fields for two 21-d periods, one prior to and one following actual exposure to E and B fields, resulting in a total of five 21-d periods. Control animals were exposed to sham E and B fields for the entire 105-d interval. At the end of each 21-d period cerebrospinal fluid (CSF) was obtained by lumbar puncture and analyzed for concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), metabolites of dopamine and serotonin neurotransmitters, respectively, by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Results are based on an examination of six experimental and four control animals. Exposure to E and B fields at all strengths was associated with a significant decline in CSF concentrations of both HVA and 5-HIAA when statistical comparisons were made against values obtained at the end of the preexposure interval. However, HVA returned to preexposure levels during the postexposure period, while 5-HIAA did not. No significant change in the concentrations of HVA or 5-HIAA was noted in the control animals. These results strongly suggest that exposure of the nonhuman primate to E and B fields can significantly affect specific biochemical estimates of nervous system function. These effects may involve alterations either in neuronal activity or in the activity of enzymes that catabolize the neurotransmitters.