Effects Of Ginsenosides Rg1 On [Ca²⁺]_i In Primary Cultured Rat Hippocampal Neurons Subjected To Morphine-dependence

In the history, there had been several drug abuse confined to specific countries and regions, for example, the prevalence of mecon in America in 1861, the popularity of MDMA in Japan from 1946 to 1956, and the spread of opium in old China. Although drug abuse caused terrible disaster in these regions, one kind of drug didn't spread in the whole world, and the drug abuse could be effectively controlled after taking effective drug prohibition measures. In these last 30 years, it was more and more popular for drug abuse in the whole world, and drug abuse had become one of public hazard.Drug abuse can cause negative health and social consequences. For one thing, it severely damages one's health physically and mentally, for another, it has a bad influence on social stability and economic development in the regions of drug production and drug consume. The harm and abominable impact on society induced by drug abuse exceed much more than that of any plague, and the disaster is inconceivable, so all of the countries and people should pay enough attention to it.From 1980's, with the development of reform and opening policy, the numbers of drug abuse and drug smuggling have been increased. Although the government has taken many measures to inhibit drug smuggling, the numbers of drug abuse and drug smuggling didn't decrease, instead it increased more quickly. Therefore, drug abuse is considered as public disruption and mortal disease of a society. Especially in these recent years, many new drugs have appeared, which made drug prohibition much more difficult. In the past, the drug abuse mainly included the traditional narcotics, such as bang and cocain, but recently, drug abuse mainly depend on more toxic psychopharmaca, such as MDMA and heroin. All these drugs have much stronger psychological dependence, so we have to meet another difficult challenge of drug abuse.The abuse of morphine will lead to drug tolerance and physical dependence. Drug tolerance is a condition that occurs when the body gets used to a medicine so that either more medicine is needed or different medicine is needed. Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction. The higher the dose used typically the worse the physical dependence and thus the worse the withdrawal syndrome. Withdrawal syndromes can last days, weeks or months or occasionally longer and will vary according to the dose and the individual person. Depending primarily on the drug's elimination half-life, withdrawal symptoms can appear within a few hours to several days after discontinuation. Common symptoms of withdrawal syndrome include psychosocial dysfunction, anhedonia, depression, sleep disturbances, poor appetite, increased sensitivity to pain, impaired concentration, diarrhea and so on. The treatment of acute withdrawal syndrome emphasizes immediate and strong effect, so amidone is the best choice for substitution therapy. But for chronic withdrawal syndrome, there haven't been ideal therapy methods yet. Because traditional medicine have many advantages, for example, no dependence, safety and multitargets, tranditional medicine has great potential to treat withdrawal syndrome. Chinese traditional medicine is considered as the best choice for morphine-dependent patients. The traditional medicine can not only release the physical and psychological symptoms, but also would treat withdrawal syndrome.Ginseng belongs to Araliaceare and Panax ginseng. Active constituents found in most ginseng species include ginsenosides, polysaccharides, peptides, polyacetylenic alcohols, prostisol and fatty acids. Ginseng contains over forty ginsenosides, and single ginsenosides have been shown to produce multiple effects in the same tissue. In addition, non-ginsenoside constituents of ginseng also exert pharmacological effects. However, most pharmacological actions of ginseng are attributed to ginsenosides. More than forty-eight ginsenosides have been isolated, and novel structures continue to be reported. Ginsenosides Rg1 is the most important ingredient in ginseng to ameliorate some adverse effects of morphine. Apart from detoxification, it has many other roles, such as immunomodulatory effects, anti-aging, neurotransmitter modulation and intelligence development.The hippocampus is a brain structure located inside the medial temporal lobe of the cerebral cortex, and therefore is part of the telencephalon (forebrain). It belongs to the limbic system and plays major roles in short term memory and spatial navigation. Recent researches found the hippocampus was involved in physical dependence and psychological dependence induced by morphine, and it would also prevent relapse. It was reported that the intracellular free Ca²⁺ concentration ([Ca²⁺]_i) in the hippocampus neuron changed significantly, when the rat appeared morphine-dependent symptoms and withdrawal syndromes. Therefore, we intend to visualize and quantify changes in intracellular calcium in hippocampus neuron using laser scanning confocal microscopy (LSCM). After the primary cultured hippocampal neurons subjected to morphine-dependence were respectively treated with ginsenosides Rg1 (1μmol/L, 10μmol/L and 100μmol/L), changes of [Ca²⁺]_i induced by ginsenosides Rg1 were detected by use of Fluo-3/AM as a calcium fluorescent probe.The results indicated that the [Ca²⁺]_i of hippocampal neurons subjected to morphine-dependence was 1.8 times much higher than that of normal neurons, and the difference was significant (t=7.229, P=.000 ). After treated with ginsenosides Rg1 (1μmol/L, 10μmol/L and 100μmol/L), changes of [Ca²⁺]_i in normal hippocanpal neuron didn't change significantly (F-0.091, P =0.964 ), however, ginsenosides Rg1 significantly reduced [Ca²⁺]_i of hippocampal neurons subjected to morphine-dependence in a dose-dependent manner (F=16.398, P=0.000 ). These results showed that ginsenosides Rg1 may effectively block the the increase of [Ca²⁺]_i induced by morphine and morphine addiction, and supplied experimental proof for ginseng as a detoxification drug safely and reasonably.