[Effect of Corydalis Rhizoma and L-tetrahydropalmatine on dopamine system of hippocampus and striatum in morphine-induced conditioned place preference rats].

To investigate the effects of Corydalis Rhizoma and L-tetrahydropalma-tine (L-THP) on the levels of dopamine neurotransmitter (DA), dopamine transporter (DAT) and the second dopamine receptor (D2R) in learning and memory-related brain areas, hippocampus and striatum, the DA, DAT and D2R were detected in conditioned place preference (CPP) rats suffered from morphine. And comparation the degree of similarity and consistency of the pharmacological effects was also studied. The rats were trained in black compartments and white ones (drug-paired compartment) with the increasing doses of morphine for 10 days (hypodermically injected from 10 mg•kg⁻¹ to 100 mg•kg⁻¹). Models of CPP were validated in those psychological dependence rats after 48 h training. The dopamine contents were detected as soon as the materials of hippocampus and striatum are harvested from rats of NS control group and model group. The DAT and D2R levels are measured by Western blot. The high, medium and low dose group of Corydalis Rhizoma are given Corydalis Rhizoma 2, 1, 0.5 g•kg⁻¹ water extraction liquid respectively (which contains L-THP were 0.274, 0.137 and 0.137 mg respectively), and the high, medium and low dose group of L-THP were given L-THP 3.76, 1.88, 0.94 mg•kg⁻¹ lavage treatment respectively, NS treatment group were lavaged normal saline for 6 days and they were killed after test of CPP, again tested DA levels and expression of DAT and D2R similar to the front of materials. The reduction effects of CPP were observed in the groups of both Corydalis Rhizoma (2, 1 g•kg⁻¹) and L-THP (3.76, 1.88 mg•kg⁻¹) subjected to medicine for 6 days (P<0.01). Compared with the NS treatment group and the model group, the higher values including in the contents of neurotransmitter dopamine were detected of hippocampus and striatum (P<0.01, P<0.05), the DAT and D2R protein expression of Corydalis Rhizoma (2, 1 g•kg⁻¹) and L-THP (3.76, 1.88 mg•kg⁻¹) increased in hippocampus and striatum (P<0.01). Learning and memory-related brain regions hippocampus and striatum was another neuroanatomical sites of action in the treatment of mental dependence of fumarate and L-THP, its mechanism was related to lowering its elevated DA neurotransmitter levels, and increasing the expression of DAT and D2R. Corydalis Rhizoma could be play 14-times roles in effect of L-THP. The similar effects were observed on the neurotransmitter dopamine, DAT and D2R in learning and memory-related brain areas, hippocampus and striatum of the morphine- dependent rats.

[Effect of Corydalis yanhusuo and L-THP on Gastrointestinal Dopamine System in Morphine-Dependent Rats].

OBJECTIVE: To investigate the protective mechanism of Corydalis yanhuso and L-THP in morphine-dependent gastrointestinal injury rats. METHODS: 180 male rats were randomly divided into nine groups, 20 rats for each group: saline group (N), model group (M), NS treatment group and three different dosage of Corydalis yanhusuo and L-THP groups (low dose group,middle dose group and high dose group). The rat CPP (conditioned place preference) model was established by injecting the rats with an increasing dosage of morphine, all groups received CPP training in a black compartments and white ones (drug-paired compartment) for ten days. At 48 h after the final training, the performance of CPP models were assessed to make sure all models were exported correctly. Then the treatment groups were administered with different concentration of Corydalis yanhuso (0.5, 1 and 2 g/kg) and L-THP (0.94, 1.88 and 3.76 mg/kg) for six days. All rats were immediately killed after finish the last CPP test. For each group, ten rats were killed to detect the contents of DA in the stomach and duodenum through the fluorescence spectrophotometer. The expression levels of D2 receptor( D2R) in different tissues (gastric cardia, gastric body, pylorus and duodenum) were checked by Western-blot in the other rats. RESULTS: In the NS treatment group, the time when rats stay in the white ones were significantly decreased compared with the Corydalis yanhusuo treated groups (1 and 2 g/kg) and L-THP treated groups (1.88 and 3.76 mg/kg) (P < 0.01), the high expression of DA contents in the stomach and duodenum were significantly decreased (P < 0.01). However the protein level of D2R were notably lower in gastric cardia, gastric body, pylorus and duodenum (P < 0.01). CONCLUSION: Injuries of the gastrointestinal tract followed lower DA contents and an abnormal increase of D2R in the stomach and duodenum of rats, which induced by morphine-dependent could be reversed by treatment with Corydalis yanhusuo and L-THP. This is one of mechanism underlying the protective effects of gastrointestinal tract in morphine-dependent rats.