Effects of prenatal X‐irradiation on the 14th–18th days of gestation on postnatal growth and development in the rat

Abstract

Thirty-nine pregnant adult Wistar strain rats were randomly assigned to one of three exposure groups: 0, 0.75, or 1.50 Gy X-radiation total exposure. Animals were exposed from the 14th to the 18th days of gestation at 0, 0.15, or 0.30 Gy per day. At term, 15 rats were killed and morphologic analyses were completed. Twenty-four rats were allowed to deliver their offspring. On the first day of postnatal life, litters were reduced to a maximum of eight pups per litter, with equal numbers of male and female offspring wherever possible. A total of 187 pups were observed for the age of acquisition of five reflexes (air righting, surface righting, visual placing, negative geotaxis, auditory startle) and the appearance of four physiologic markers (pinna detachment, eye opening, vaginal opening, testes descent). There was significant dose-related weight reduction in term fetuses and offspring throughout the 86-day postnatal period. Postnatal growth rate (g gained/day) was unaffected. Adult offspring brain and gonadal weight and organ weight:body weight ratios were reduced. Using the PAC50 methodology, dose-related alterations occurred in the acquisition of several reflexes. All physiologic markers exhibited a dose-related delay in appearance. These results indicate that fractionated exposure to X-radiation during the fetal period in the rat results in dose-dependent alterations in postnatal growth and physiologic development. These studies are important for our understanding of the long-range effects of prenatal exposure to ionizing radiation late in gestation.

Behavioral consequences of radiation exposure to simulated space radiation in the C57BL/6 mouse: Open field, rotorod, and acoustic startle

“…For example, granule cell agenesis and hypoplasia in the neonatal rat hippocampus are induced by exposure to X-and gradiation (Jensh & Brent, 1988;Mickley & Ferguson, 1989;Mintz, Yovel, Gigi, & Myslobodsky, 1998) at doses of 13 Gy and above. In the adult guinea pig, g-or Xirradiation in the 5-to 10-Gy range can significantly impair the ability of hippocampal (CA1) neurons to generate and maintain the membrane potentials required for axonal spikes and synaptic function, with the duration of the impairment being 5-7 days (Pellmar & Lepinski, 1993;Tolliver & Pellmar, 1987).…”

Utilization of juvenile animal studies to determine the human effects and risks of environmental toxicants during postnatal developmental stages

“…From the perspective of biological plausibility and the results of animal studies, it would seem that the data favor the viewpoint that mental retardation is a deterministic effect with a threshold above 0.2 Sv (Brent et al, 1986, 1987; Jensh and Brent, 1986, 1987, 1988; Jensh et al, 1986, 1987; Brent, 1999; Miller, 1999). Histological examination of the irradiated brain exposed to 0.01 Sv shows no pathological consequences that could account for severe mental retardation (Jensh et al, 1995).…”

Protection of the Gametes Embryo/Fetus From Prenatal Radiation Exposure

“…During later stages, the fetus is not grossly deformed by radiation but can exhibit permanent cell depletion of various organs and tissues if the dose is high enough (Brent and Gorson 1972;Brent 1977;, 1988a, 1988bKameyama and Inouye 1994) (Table 3).…”

“…phenomena that can only be evaluated at later life stages (Cowen and Geller 1960;Murphree and Pace 1960;Brent and Bolden 1961;Furchtgott 1963;Wohlfromm 1964a, 1964b;Hicks and D'Amato 1966;Wood et al 1967aWood et al , 1967bWood et al , 1967cMiller 1969;Brent 1970;Brent and Gorson, 1972;, 1988a, 1988bKamayana and Inouye 1994;Preston et al 2008). …”