OBJECTIVETo investigate the mechanism of the apoptosis-inducing effects of dopamine on K562 leukemia cells.

METHODSK562 cells were treated with DP2785, the dopamine receptors were detected with fluorescence spectrophotometer, UV spectrophotometer and fluorescence microscope; the contents of cAMP in K562 cells were measured; and the subtypes of dopamine receptor on K562 cells were analyzed by receptor blocking.

RESULTThe existence of dopamine receptors in K562 cells was demonstrated by fluorescence microscopy, UV spectrophotometer and fluorescence spectrophotometer. Dopamine enhanced the contents of cAMP in K562 cells. Dopamine receptors were blocked by both D1 and D2 antagonists.

CONCLUSIOND1 and D2 dopamine receptors may be involved in dopamine-induced apoptosis of K562 cells, and dopamine can also increase the contents of cAMP in K562 cells.

Apoptosis ; drug effects ; Cyclic AMP ; metabolism ; Dopamine ; pharmacology ; Humans ; K562 Cells ; Microscopy, Fluorescence ; Receptors, Dopamine D1 ; metabolism ; Receptors, Dopamine D2 ; metabolism ; Spectrometry, Fluorescence ; Spectrophotometry, Ultraviolet

OBJECTIVETo explore the mechanism underlying the therapeutic effect of Bushen Huoxue Decoction (BHD), a traditional Chinese medicinal preparation, on dopamine D2 receptor (DRD2) in the brain of rat models of Parkinson's disease (PD).

METHODSA total of 120 SD rats were randomized into normal control group, saline model group and BHD-treated group. In the latter two groups, PD rat models were established by direct injection of 6-OHDA to destruct the substantia nigra compact part (SNC) with corresponding treatments. The behavioral changes of the rats were observed. Radioimmunoassay was employed to determine the changes in the equilibrium dissociation constant (Kd) and maximal binding capacity (B(max)) of DRD2, and immunohistochemistry was used to observe the number of the DRD2-positive cells in the brain of the rats.

RESULTSBHD can markedly improve the behavioral abnormalities of PD model rats. Compared with those in the saline model group, the B(max) of DRD2 in the damaged hemisphere increased while the Kd of BHD decreased significantly after BHD treatment (P<0.01). The number of DRD2-positive cells in BHD-treated group was significantly higher than that in the model group (80.9∓13.59 vs 11.15∓6.78, P<0.01), but showed no significant difference from that in the normal control group (P>0.05).

CONCLUSIONBHD can improve the behavioral abnormalities and increase the cerebral expression and affinity of DRD2 in PD rat models.

Animals ; Brain ; metabolism ; Drugs, Chinese Herbal ; therapeutic use ; Female ; Parkinson Disease ; drug therapy ; metabolism ; Phytotherapy ; Rats ; Receptors, Dopamine D2 ; drug effects ; metabolism

Intermittent administrations of dopaminergic agents in hemiparkinsonian rat enhances the behavioral response to subsequent administration of the drugs. This phenomenon is known as "priming" and thought as comparable to drug-induced dyskinesia in patients with Parkinson's disease. We investigated the behavioral and electrophysiological changes in 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian rats after repeated administrations of apomorphine. Administration of apomorphine (0.32 mg/kg, intraperitoneal, i.p.) twice daily for 6 days enhanced the rotation induced by apomorphine from 341 turns/hour at the beginning to 755 turns/hr at the end. At the same time, the response to selective D2 agonist quinpirole (0.26 mg/kg, i.p.) was also enhanced from 203 to 555 turns/hr. Extracellular single unit recording revealed no significant difference in the basal firing rates of substantia nigra pars reticulata (SNr) neurons between the ipsilateral and contralateral side of the 6-OHDA lesion regardless of the repeated administrations of apomorphine. In SNr of the lesion side, the units with burst firing pattern were found more frequently after repeated administrations of apomorphine and the suppressive effect of quinpirole on the firing rate was enhanced. These findings suggest that the increased percentage of the burst units is the important electrophysiological change in the development of enhanced response to selective D2 agonist.
Animal ; Apomorphine/*pharmacology ; Dopamine Agonists/*pharmacology ; MPTP Poisoning/physiopathology ; Male ; Oxidopamine/toxicity ; Parkinsonian Disorders/*physiopathology ; Quinpirole/pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine D2/*drug effects ; Substantia Nigra/*drug effects/physiology

OBJECTIVETo detect the expression of dopamine receptor D2 in different pulmonary carcinoma cells and investigate the effect of dopamine in inducing apoptosis of A549 cells.

METHODSWestern blotting and RT-PCR were employed to detect the expression of dopamine receptor D2 in different pulmonary carcinoma cells (95D, H460, GLC-82, A549 and H446 cells). The apoptosis of A549 cells after a 6-hour exposure to 0.02%, 0.04%, 0.08% and 0.1% dopamine was analyzed by flow cytometry. The apoptosis-inducing effect of dopamine in vivo was also tested by intratumoral injection of 1% dopamine in 2 BALB/c-nu mice bearing A549 tumor xenograft using flow cytometry.

RESULTSThe presence of dopamine receptor D2 expression was detected by Western blotting and RT-PCR in 95D, H460, GLC-82, A549 and H446 cells. Flow cytometry detected obvious apoptosis of A549 cells following dopamine exposure in vitro in positive correlation to dopamine concentration. In the tumor-bearing mice, dopamine also showed an obvious apoptosis-inducing effect on A549 cells.

CONCLUSIONDopamine receptor D2 exists extensively in different pulmonary carcinoma cells. Dopamine may promote the apoptosis of pulmonary carcinoma cells through dopamine receptor D2.

Adenocarcinoma ; metabolism ; pathology ; Animals ; Apoptosis ; drug effects ; Cell Line, Tumor ; Dopamine ; pharmacology ; Flow Cytometry ; Humans ; Lung Neoplasms ; metabolism ; pathology ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Receptors, Dopamine D2 ; metabolism

OBJECTIVE: To investigate the expression of dopamine D2 receptors (D2R) and dopamine transportors (DAT) located in the medial prefrontal contex (mPFC) in high and low conditioned place preference (CPP) rats, and to unveil the possible mechanism leading to different CPP susceptibilities. METHODS: One hundred and sixty male Sprague-Dawley rats were randomly assigned into an experiment group (n = 130) and a control group (n = 30). The experiment group was re-classified into 2 groups according to CPP values:high preference group (HP group) and low preference group (LP group). According to the execution time-points after the last administration, the HP and LP group was classified into a 3-hour group (3 h), a 72-hour group (J3d), and a 14-day group (J14d), respectively. At 3 hours, 72 hours, and 14 days after the final injection, rats were killed and cardio-perfused, and the brains were removed and sliced up coronarily. The mRNA levels of D2R and DAT in mPFC were determined with in situ hybridization. RESULTS: There were no significant differences of pretest scores staying at the non-preference chamber among the groups(P = 0.470). However, the test scores of the CPP time stayed at pretest natural preference in the HP group were significantly higher than those of the LP group(P = 0.000). In 3h, J3d, and J14d groups,the expressions of D2R mRNA in the HP group (125.43 +/- 2.90 approximately 142.92 +/- 3.32) were lower than those of LP group (122.25 +/- 2.20 approximately 136.67 +/-5.39) (P = 0.000). In 3h and J3d,the expressions of DAT mRNA in the HP group (157.00 +/- 3.55 approximately 145.15 +/- 3.69) were significantly lower than those of the LP group (150.69 +/- 3.12 approximately 138.84 +/- 3.99) (P = 0.000). In J14d, there were no differences among 3 groups in mPFC (P = 0.458). CONCLUSION D2R and DAT may be correlated closely and underlie the different susceptibilities to morphine induced CPP.
Animals ; Conditioning, Psychological ; drug effects ; Disease Susceptibility ; metabolism ; Dopamine Plasma Membrane Transport Proteins ; biosynthesis ; genetics ; Male ; Morphine Dependence ; metabolism ; Prefrontal Cortex ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine D2 ; biosynthesis ; genetics

OBJECTIVETo evaluate the effect of Qufeng Zhidong Recipe (QZR) on the head tic behavior, and the mRNA expressions of Notch1 and dopamine D2 receptor (D2R) in tic disordered mice.

METHODSMouse model like wet-dog shake head tic disorder was established by peritoneal injection of 5-HT2A/C agonist DOI for 14 successive days. The model mice were divided into three groups, the model group, the Chinese medicine (CM) treated group and the Western medicine (WM) treated group, they were intervened respectively with distilled water, QZR (10 g/kg) and haloperidol (1 mg/kg). Besides, a normal control group was set up and gastrogavaged with distilled water. The effect of intervention was evaluated 2 weeks later by estimating the head tic and the creeping distance of animals, and the mRNA expressions of D2R and Notch1 in corpus striatum and prefrontal cortex regions were detected using Real-time PCR.

RESULTSThe wet-dog shake response and the creeping distance of mice were significantly reduced after intervention in both intervened groups, showing insignificant difference between the effects of CM and WM (P > 0.05). The expression of D2R mRNA in corpus striatum was higher than that in the prefrontal cortex (P < 0.01), at the prefrontal cortex, it was 151 +/- 30 in the CM group and 180 +/- 41 in the WM group, and at the corpus striatum, 710 +/- 64 and 850 +/- 80 respectively, all higher than those in the model group (P < 0.05). While the Notch1 mRNA expression in model mice were lower at the prefrontal cortex than at the corpus striatum (P < 0.05). After intervention it was 55 +/- 20 in the CM group and 48 +/- 23 in the WM group at the prefrontal cortex, all significantly lower than that in the model group (P < 0.05).

CONCLUSIONDOI-induced wet-dog shake response could well simulate the clinical characteristics of tic disorder; QZR could improve the tic behavior and creeping distance in the model mice. The up-regulation of D2R mRNA expression after QZR intervention may be related with the down-regulation of Notch1 expression, this findings is worthy of further studies.

Animals ; Corpus Striatum ; metabolism ; Drugs, Chinese Herbal ; therapeutic use ; Male ; Mice ; Mice, Inbred C57BL ; Phytotherapy ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Receptor, Notch1 ; genetics ; metabolism ; Receptors, Dopamine D2 ; genetics ; metabolism ; Signal Transduction ; drug effects ; Tic Disorders ; drug therapy

OBJECTIVETo further investigate whether the functional polymorphisms of dopamine D2 receptor (DRD2) and dopamine D3 receptor (DRD3) genes associate with the development of tardive dyskinesia (TD) in schizophrenia, and whether the interactive effects of DRD2, DRD3, 5-hydroxytryptamine 2C receptor (HTR2C) and manganese superoxide dismutase (MnSOD) genes contribute to the severity of TD.

METHODSThe patients with schizophrenia were assessed for TD by the Abnormal Involuntary Movement Scale (AIMS). Eventually, 42 schizophrenics with persistent TD were in the TD group, and 59 schizophrenics without TD were in the non-TD group. The polymorphism of each candidate gene was analyzed using a polymerase chain reaction-based restriction fragment length polymorphism analysis.

RESULTSThe genotype distributions of the candidate genes in the groups were all consistent with the Hardy-Weinberg equilibrium. Allele frequencies for -759C/T and -697G/C polymorphisms in HTR2C gene showed a significant excess of -697 variant (P<0.05) in the patients with TD, compared against those in patients without TD. There were no differences in the distributions of the allelic frequencies and genotypes of Taq I. A polymorphism in DRD2 gene, of Ser/Gly polymorphism in DRD3 gene, and of Ala-9Val polymorphism in MnSOD gene between the TD group and non-TD group (P>0.05). Interestingly, as compared with the other joint allelic types, a significant excess of carrying both DRD3 variant allele (Gly) and MnSOD wild allele (Val) was found in the TD group (P<0.05). However, neither the allele and genotypes nor the clinical demographic characteristics contributed to the higher total AIMS scores in the patients of the TD group. There were no significant differences in any of the clinical demographic characteristics between the subgroups of any genotype in TD and non-TD groups.

CONCLUSIONThe excess of -697 variant in the promoter regulation region of the HTR2C gene may be a risk factor for the susceptibility to the occurrence of TD in Chinese male patients with schizophrenia. A combination of DRD3 variant allele (Gly) and MnSOD wild allele (Val) may increase the susceptibility to the development of TD.

Aged ; Alleles ; Antipsychotic Agents ; adverse effects ; therapeutic use ; Dyskinesia, Drug-Induced ; etiology ; genetics ; Female ; Gene Frequency ; Genetic Variation ; Genotype ; Glycine ; genetics ; Haplotypes ; Humans ; Male ; Middle Aged ; Mutation ; Receptor, Serotonin, 5-HT2C ; Receptors, Dopamine D2 ; genetics ; Receptors, Dopamine D3 ; Receptors, Serotonin ; genetics ; Schizophrenia ; drug therapy ; Superoxide Dismutase ; genetics ; Valine ; genetics

We performed this study in order to verify the heart rate decrease caused by the D2-receptor on cardiac sympathetic nerve endings and its relation to the concentration of norepinephrine in synaptic clefts. Sprague-Dawley rats were pithed and the heart rate was increased either by electrical stimulation of the cardiac accelerator nerve or by intravenous infusion of norepinephrine, tyramine, or isoproterenol. Increased heart rate by electrical stimulation of cardiac accelerator nerve was dose-dependently lowered by lisuride and its effect was blocked by pretreatment with sulpiride but not with yohimbine and SCH 23390. Also, the heart rate was decreased in a dose-dependent manner by clonidine and this effect was blocked by pretreatment with yohimbine, but not with sulpiride. For increased heart rate by infusion of norepinephrine, tyramine, or isoproterenol, the heart rate lowering effect of lisuride was more marked in the norepinephrine-and tyramine-infusion groups, in which the intrasynaptic concentration of norepinephrine was elevated, compared to the isoproterenol-infusion group, in which intrasynaptic concentration of norepinephrine was not elevated. In conclusion, there is a D2-receptor on the cardiac sympathetic nerve endings which decreases the heart rate and is different from the presynaptic alpha 2-receptor. Also, the heart rate lowering effect via stimulation of the D2-receptor by lisuride was more marked with increased concentration of norepinephrine in the synaptic cleft.
Animal ; Female ; Heart/innervation ; Heart Rate/drug effects/*physiology ; Lisuride/pharmacology ; Male ; Norepinephrine/metabolism ; Rats ; Receptors, Dopamine D2/*physiology ; Support, Non-U.S. Gov't ; Sympathetic Nervous System/metabolism ; Synapses/metabolism ; Yohimbine/pharmacology

OBJECTIVETo study and compare the effect of Corydalis yanhusuo and L-THP on dopamine neurotransmitter and D2 receptor of reward circuitry in various cerebral areas of conditioned place preference model rats and the comparison of their effects.

METHODThe CPP model was established by injecting morphine in rats with increasing doses for 10 days. The initial dose of 10 mg x kg(-1), and the final dose of 100 mg x kg(-1), with 10 mg x kg(-1) increased each day. At 48 h after the final training, CPP was adopted to detect the successful establishment of the model. On the same day (12 d), they were orally administered with 2, 1, 0.5 g x kg(-1) C. yanhusuo (containing 0.153, 0.077 and 0.038 mg L-THP) and L-THP (3.76, 1.88, 0.94 mg x kg(-1)) for six days. On 18 d, CPP test was performed again. Next day, HPLC was adopted to determine the content of dopamine neurotransmitters of reward circuitry in VTA-NAc-PFC; Immunohistochemistry and Western blotting were adopted to detect the expression of D2 receptors.

RESULTCompared with the physiological saline treatment group, C. yanhusuo (2, 1 g x kg(-1)) and L-THP (3.76, 1.88 mg x kg(-1)) groups showed that rats stayed in a notably shorter period in white boxes (morphine-accompanied boxes) (P < 0.01 or P < 0.05), and revealed a remarkably lower dopamine content in VTA, NAc and PFC and the significant increase in the expression of D2 receptor (P < 0.01 or P < 0.05).

CONCLUSIONThe down-regulation of the increased dopamine content in reward nervous circuitry and the up-regulation of the expression of D2 receptor may be one of mechanisms of C. yanhusuo and L-THP in accelerating the recession of morphine's CPP effect Regarding the inhibition of morphine's CPP effect and the effect on dopamine system, the effect of C. yanhusuo traditional Chinese medicine containing one-fold L-THP monomer is equal to that of the independent application of around 24-fold L-THP monomer.

Animals ; Berberine Alkaloids ; administration & dosage ; Brain ; drug effects ; metabolism ; physiopathology ; Conditioning, Operant ; drug effects ; Corydalis ; chemistry ; Dopamine ; metabolism ; Humans ; Male ; Morphine ; adverse effects ; Plant Extracts ; administration & dosage ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine D2 ; genetics ; metabolism ; Substance-Related Disorders ; drug therapy ; genetics ; metabolism ; psychology