Deep brain stimulation of the lateral hypothalamic area alters dopamine receptors in the prefrontal cortex of morphine-dependent rats

The lateral hypothalamus (LH) is a main component of the brain’s reward circuit. Previous studies have shown that high-frequency deep brain stimulation (DBS) of the LH prevents morphine-induced place preference in rats. In the present study we evaluated the effect of intra-LH DBS on the levels of dopamine receptors in the prefrontal cortex.

Electrodes were implanted into the LH bilaterally. Rats were allocated to four different groups: morphine-DBS, saline-DBS, morphine-sham, and saline-sham. Morphine (5mg/kg.sc) and saline were given in four consecutive days immediately followed by DBS (130 Hz pulse repetition frequency, 150 µA pulse amplitude, and 100 μs pulse width) or sham-DBS for 30 min corresponding to the experimental group. One day after the last injection rats were sacrificed and the prefrontal cortex was dissected for assaying dopamine receptors and c-fos mRNA expression.

Morphine increased D1 receptor, decreased D2 receptor, and had no effect on D3, D4, and D5 receptors. DBS in morphine-treated rats prevented the elevation of D1 receptor, increased D2 and D3 receptors, decreased D5 receptor, and had no effect on D4 receptors. Morphine decreased c-fos mRNA levels in the prefrontal cortex and DBS increased it.

DBS of LH influenced the brain’s dopaminergic system particularly in the prefrontal cortex.