RESUMEN
Objective The molecular basis for opiate tolerance and dependence remains poorly understood despite extensive investigation in several preparations, including the hippocampus. Recent studies have implicated that the hippocampus played a central role in opiate tolerance, dependence and withdrawal. The current study is to explore the change in guanine nucleotide binding protein-inhabitant (Gi_2) protein in primary cultured hippocampal neurons with morphine treament. Methods The hippocampus was harvested from newborn Sprague-Dawley rats. Primary hippocampal neuronal cultures of 7 days in vitro were used and divided randomly into six groups (n=6), i.e. morphine treatment 4h group (M4), 8h group (M8), 16h group (M16), 24h group (M24), 48h group (M48) and control group (C). All morphine treatment groups were treated with morphine (10?mol/L). C group was treated with saline. The G protein levels were determined with immunofluorscence and laser scanning confocal microscope (LSCM) imaging techniques. Results Gi_2 protein levels in M16, M24 and M48 groups decreased significantly compared with that in C group (P0.05). Among M16, M24 and M48 groups, Gi_2 protein level was lowest in the M48 group. Conclusion The results indicated that Gi_2 protein levels decreased significantly in primary cultured hippocampal neurons with morphine treatment, which might be a potential molecular mechanism of opioid tolerance and dependence.
RESUMEN
Objective To investigate the changes in inhibitory guanine nucleotide binding protein Gi_2 in five brain regions of morphine addicted rats: ventral tegmental area, nucleus accumbens, prefrontal cortex, hippocampus and locus caeruleus. Methods 36 adult male SD rats were randomly divided into six groups (n=6): acute morphine dependent group, acute abstinence group, acute control group, chronic morphine dependent group, chronic abstinent group and chronic control group. Morphine dependent models were reproduced. Withdrawal syndrome was induced with naloxone 5mg/kg for 30min in rats of abstinence group. All rats were sacrificed by decapitation. Frozen sections of coronal plane of respective brain regions (ventral tegmental area, nucleus accumbens, prefrontal cortex, locus coeruleus, hippocampus) were prepared. The relative concentrations of Gi_2 protein were determined with immunohistochemical methods. Results Gi_2 proteins in acute morphine dependent group and acute abstinence group were significantly decreased compared with that of acute control group in nucleus accumbens (P