Early adoption modifies the effects of prenatal stress on dopamine and glutamate receptors in adult rat brain

Abstract

Stressful stimuli during pregnancy induce complex effects that influence the development of offspring. These effects can be prevented by environmental manipulations during the early postnatal period. Repeated restraint during the last week of pregnancy was used as a model of prenatal stress, and adoption at birth was used to change the postnatal environment. No differences were found in various physical landmarks, except for testis descent, for which all prenatally stressed pups showed a 1-day delay in comparison with control rats, regardless of the postnatal adoption procedure. Levels of dopamine (DA) D(2) and glutamate (Glu) N-methyl-D-aspartate (NMDA) receptors were differentially regulated in different forebrain regions of cross-fostered adult offspring. Increased concentrations of cortical D(2) receptors detected in stressed pups, raised by a gestationally stressed biological mother, were not detected when the pups were raised by a control mother. Control pups raised by a foster mother whether gestationally stressed or not had higher levels of NMDA receptors in cortical areas. These findings suggest that the normal expression of DA and Glu receptors is influenced by in utero experience and by lactation. The complex pattern of receptor changes reflects the high vulnerability of DA and Glu systems to variations both in prenatal and in postnatal environment, particularly for cortical D(2) receptors and NMDA receptors in cerebral cortex and nucleus accumbens. In contrast, testis descent appears to be more susceptible to prenatal than to postnatal environmental events.

Prenatal Stress Enhances Responsiveness to Cocaine

“…Our findings for NAC dopamine are consistent with previous reports of dopaminergic alterations following either PNS or prenatal glucocorticoid receptor agonist administration that include higher dopamine content and/ or higher dopamine metabolism (metabolite : neurotransmitter ratio) in striatal tissue, increased numbers of tyrosine hydroxylase-positive cells in the ventral tegmental area, and changes in NAC D2 and D3 receptor expression (eg Alonso et al, 1994;Barros et al, 2004;Berger et al, 2002;Diaz et al, 1995;Henry et al, 1995;McArthur et al, 2005). Moreover, the enhanced dopamine response to cocaine produced by PNS is similar to that reported in neonatal isolates (Kehoe et al, 1996;Kosten et al, 2004aKosten et al, , 2003Kosten et al, , 2005Kosten et al, , 2006; see also Howes et al, 2000 for similar results following juvenile isolation) or in rodents subjected to neonatal anoxia (Juarez et al, 2003) in response to other psychomotor stimulant drugs.…”

“…Moreover, PNS rats raised by unstressed foster mothers show normalized glucocorticoid response to stress (Maccari et al, 1995) and normalized dopamine, glutamate, and g-aminobutyric acid receptors throughout limbic circuits (Barros et al, , 2006. However, adoption to unstressed mothers can produce similar or opposite effects in rats not exposed to PNS (Maccari et al, 1995;Barbazanges et al, 1996;Barros et al, 2004Barros et al, , 2006, suggesting that both the pre-and postnatal environments are important determinants of the adult's responsiveness to psychostimulant drugs. Future studies will need to determine which aspects of the behavioral and neurochemical abnormalities in cocaine responsiveness observed in PNS rats are due to alterations in neurodevelopment during gestation and which are produced or maintained during postnatal development.…”

Sleep and Behavior in Cross-Fostering Rats: Developmental and Sex Aspects

“…20 In this method, the pup litters are changed between mothers closer to the end of critical postnatal period (at the age of P5-12), which is proven be the age that is sensitive to environmental stimulation. Pups that are raised by foster mothers, which have adopted them during late stages of the infancy period (from P5 on), have higher stress reactivity and impairment of cognitive functioning 21,22 than pups raised by their own mothers, 20 or pups which were adopted during earlier stages of their development (P1-2). Whether this procedure induces changes also in sleep and sleep-related regulatory factors in adulthood has not previously been studied.…”

Astrocyte–neuron vulnerability to prenatal stress in the adult rat brain

“…DA D 2 and metabotropic group III Glu receptors increased in cortical regions and N-methyl-Daspartate (NMDA) receptors increased both in cerebral cortex and basal ganglia of prenatally stressed adult rats (Berger et al, 2002). Moreover, early adoption modified the effects of prenatal stress; i.e., the increase in DA D 2 receptors was not detected when the pups were raised by a control, nonstressed mother (Barros et al, 2004).…”