Isolation rearing in rats: pre- and postsynaptic changes in striatal dopaminergic systems

Area of Science:

• Neuroscience
• Behavioral Science
• Neurochemistry

Background:

• Isolation rearing in rats is known to induce behavioral changes linked to altered dopamine (DA) function in the nucleus accumbens (NAC).
• Previous research suggests a connection between early life stress and neurochemical alterations.

Purpose of the Study:

• To investigate the effects of isolation rearing on presynaptic and postsynaptic dopamine function in the rat nucleus accumbens.
• To examine the interaction between isolation rearing and handling/testing on monoamine levels.
• To characterize the dose-response effects of d-amphetamine and potassium-evoked DA release in isolated rats.

Main Methods:

• In vivo microdialysis was used to measure extracellular dopamine and serotonin metabolite (5-HIAA) levels in the NAC.
• Dose-response curves for d-amphetamine and potassium-evoked DA release were determined.
• Postsynaptic function was assessed by measuring dopamine receptor-linked cAMP production in ventral striatal slices.

Main Results:

• Isolation rearing led to elevated basal DA levels and reduced extracellular 5-HIAA in the NAC.
• Both isolation and handling/testing enhanced d-amphetamine-evoked DA release, but only isolation increased basal DA.
• Potassium-evoked DA release was reduced in isolates, while postsynaptic D2 receptor function appeared downregulated.

Conclusions:

• Isolation rearing significantly alters both presynaptic and postsynaptic dopamine system function in the rat nucleus accumbens.
• These neurochemical changes likely contribute to the behavioral syndrome associated with isolation.
• The findings highlight the complex neurobiological adaptations following early-life social isolation.