Chunk #11 — Neuroendocrine and Neurobiological Consequences of Early-Life Stress — Effects of Early-Life Stress on Stress Circuitry and Mesolimbic Dopamine Reward Pathway
Studies in rats have shown that early-life stress (maternal separation or handling) has long-lasting effects on the mesolimbic dopamine pathway [9•] that is fundamental to the sensations of pleasure induced by natural rewards such as food and sex and also alcohol-/drug-related rewards. This “reward” pathway originates in the ventral tegmental area of the midbrain and projects to the nucleus accumbens, the limbic system, and the orbitofrontal cortex. Alcohol and drug intake is associated with increased synaptic dopamine in the nucleus accumbens and elsewhere in the reward pathway. Early-life stress in rats can result in profound and lasting changes in the responsiveness of dopamine neurons to stress and drugs in adulthood [43–45]. One congruent finding in humans was that a cortisol response to a psychosocial stress task was highly correlated with increased firing of dopamine neurons in the reward pathway, but only in young adults who had experienced poor parental care [46]. Exposure to early-life stress in rats also results in alterations in opiate and γ-aminobutyric acid (GABA)A receptors, and long-term changes in BDNF expression [45, 47, 48].
