Nora Mayer

Adrenal response of male rats exposed to prenatal stress and early postnatal stimulation

Abstract Stress in pregnant rats caused by chronic immobilization alters the pattern of secretion of corticosterone and modifies the hypothalamic-pituitary-adrenal axis (HPA) of the fetus. Early postnatal handling, however, may reverse the effects of increased secretion of corticosterone. We investigated the effects of prenatal stress and postnatal handling on the activity of the HPA axis of male offspring of stressed female rats. Male 90-day-old rats from four groups were investigated: prenatally stressed animals without postnatal handling, prenatally stressed animals with postnatal handling, unstressed control animals with postnatal handling, and unstressed control animals without postnatal handling. After sacrifice, the adrenal glands were weighed to determine the adrenal-somatic index. Apoptosis was evaluated by TUNEL assay and active caspase-3 expression. We found that the adrenal gland cortex:medulla ratio increased in animals with prenatal stress and that eventually the stress caused apoptosis. Handling newborns to simulate maternal activity ameliorated some of the negative effects of prenatal stress.

Attenuation effects of prenatal stress by early postnatal stimulation in different research models

The prenatal and early postnatal life stages are both dynamic and vulnerable phases during mammalian development. Exposure to adverse factors that interfere with this critical sequence of events places the exposed individual to a higher risk of developing various disorders in adult life.1–3 For instance, high blood glucocorticoids concentration in pregnant stressed females crossing the placenta and the fetal blood-brain barriers,4 can affect brain development, birth weight and HPA axis function in offspring.5

IL-2 is involved in immune response of prenatally stressed rats exposed to postnatally stimulation

espanolRESUMEN: Las condiciones ambientales influyen en el crecimiento y desarrollo de los mamiferos durante la vida prenatal, posnatal temprana y pueden ejercer efectos a largo plazo en la vida adulta. Altas concentraciones circulantes de glucocorticoides durante el embarazo (estres prenatal) afecta a la actividad del eje hipotalamo-pituitario-adrenal (HPA) de la descendencia y se encuentra en relacion con alteraciones de las respuestas del sistema inmunologico. La estimulacion postnatal temprana de los animales estresados prenatalmente genera efectos beneficiosos a largo plazo en la reactividad del eje HPA y en la funcion del sistema inmunologico. El objetivo del estudio fue investigar el efecto de las manipulaciones posnatales tempranas sobre la respuesta inmune de ratas machos y dilucidar la posible relacion con la actividad del eje HPA. Crias controles y estresadas prenatalmente (PS) por inmovilizacion (IMO) se manipularon durante la primera semana de vida. Los animales controles y PS fueron sometidos a estres agudo por la IMO. Los niveles de corticosterona (COR) plasmatica se midieron por el ensayo de RIA, la proliferacion de linfocitos T por [3H] timidina y los niveles de IL-2 por la tecnica de ELISA directa. El estres prenatal cronico por IMO aumento los niveles plasmaticos basales de COR en la madre, mientras que las crias PS sometidas a una sesion de estres agudo posnatal mostraron disminuida la proliferacion de celulas T y niveles menores de IL-2. En conclusion, las estimulaciones postnatales tempranas revirtieron los efectos negativos provocados por el estres prenatal sobre la proliferacion de los linfocitos T y la liberacion de IL-2. EnglishABSTRACT: Environmental cues influence growth and development of mammals during prenatal and particularly early postnatal life and can exert long-lasting effects in adult life. High circulating concentration of glucocorticoids during pregnancy (prenatal stress) affects the activity of the hypothalamic-pituitary-adrenal axis (HPA) of offspring and has been linked to alter immune system responses. Early postnatal stimulation (handling) of prenatally stressed animals generates long-term beneficial effects on the reactiveness of the HPA axis and immune system function. The aim of this study was to further investigate the effect of handling on immune response in prenatally stressed male rats and to elucidate a possible relationship with the HPA axis activity. Control and prenatally stressed (PS) offspring by immobilization (IMO) were handled during the first week of life. Animals from both treatments were subjected to acute stress by IMO. Corticosterone (COR) plasma concentration was measured by RIA assay, T lymphocyte proliferation by [3H] thymidine assay and IL-2 levels by direct ELISA technique. Chronic IMO prenatal stress caused an increase in mother plasma COR basal levels. Furthermore, prenatally stressed rats subjected to an acute stress session had lower T cell proliferation and decreased IL-2 release. In addition, early postnatal stimulation reversed the negative effects of prenatal stress on proliferation of T lymphocytes and IL-2 release.