Decrease in levels of thyrotrophin-releasing hormone (TRH) in the n. accumbens and lumbar spinal cord following repeated electroconvulsive shock.

The study investigated the effects of single and repeated electroconvulsive shock on levels and release of TRH in specific brain regions and thoracic and lumbar spinal cord. Whilst single electroconvulsive shock had no effect on TRH in any of the regions of the brain and spinal cord studied, repeated electroshock (5 shocks over 10 days and the rats killed 24 hr after the last shock) caused a significant decrease (-42 and -40% respectively) in levels of TRH in the nucleus accumbens and lumbar spinal cord. In the thoracic cord the level of TRH was also decreased after repeated electroshock but this did not reach significance. In contrast repeated electroshock had no significant effect on the content of TRH of the septal nuclei, hypothalamus, suprachiasmatic nucleus, or dorsal and medial raphe nuclei. Release of TRH was measured from slices prepared from nucleus accumbens and septal nuclei after repeated electroshock. A decrease in release was observed in nucleus accumbens with no effect in the septal nuclei. the results are discussed in relation to the possible interaction between dopaminergic and serotoninergic neurones and TRH in the antidepressant effects of electroconvulsive therapy.