Changes in the expression of hippocampal proteins in rats with recrudescence of morphine addiction

The high recrudescence rate of drug addiction has received attention worldwide and its mechanisms remain to be elucidated. This study aimed to analyse the disparate protein expression in the hippocampal tissue of rats with recrudescence of morphine addiction, as well as to provide clues for the exploration of the recrudescence mechanism. Sixteen male adult Sprague-Dawley rats were divided equally into the morphine and physiological saline groups. Effective nose pokes were determined as the main index. The proteins were separated using the immobilised pH gradient two-dimensional polyacrylamide gel electrophoresis (2-DE). Disparate protein spots were analysed using the PDQuest 2-DE software. Peptide dactylograms were obtained using the matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. The effective nose poke counts of the morphine group significantly increased during addiction maturation compared with the saline group (P<0.001). The post-recrudescence nose poke counts of the morphine group significantly increased compared with those before recrudescence (P<0.001). Fifteen disparate proteins were identified according to the protein electrophoresis of the morphine and physiological saline groups, including three proteins associated with energy metabolism, two ionic channel regulatory proteins, one heat shock protein and one exogenous substance metabolic enzyme. The energy metabolism and expression of cell metabolism-related proteins decreased in the hippocampus of rats with morphine recrudescence.