| 其他摘要 | Morphine have been used for thousands of years for medicinal purposes.The endogenous opioid systems induce antinociception effects through their opioid receptors.morphine used in the surgery, the wound, the burn fierce ache, as well as terminal cancer patient's three steps and ladders pain-relieving.Some effects of morphine may be therapeutically useful, including sedative,elimination anxious and fear.
Morphine induce analgesia, hypothermia, sedation, hypotension, inhibition of intestinal motility and locomotor activity, changes in mood, and depression of the immune function.Nowadays morphine is the most widely consumed illicit drugs in our country. China registered morphine addicts about 100 million annually and economic losses caused by morphine addiction more than 100 billion yuan.So
mechanism of morphine addiction and treatment is one of the key neurological
disease research.
The ligands of the endogenous opioid system, the endogenous opioid peptides and the opioid receptors are largely distributed within the central nervous system and
are also present in several peripheral tissues. Three families of endogenous peptides derived from either proopiomelanocortin,proenkephalin and prodynorphin have
been identified and cloned. Three different subtypes of opioid receptors, mu, delta and kappa, have also been identified, cloned and characterized. These receptors exist in the brain, smell the triangle, the flat peach seed, a tail shape forehead as well as spinal cord's clearance angle and latter root and so on .The morphine besides unifies the opium receptor, also possibly unifies the cannaboid receptor. Two major cannabinoid receptor subtypes, namely cannabinoid1 (CB1) and cannabinoid2 (CB2) receptors, have been cloned . Both CB1R and CB2R, with 44% sequence homology, belong to the superfamily of G protein-coupled receptors. The Human and the rat's CB1 receptor amino acid sequence has 97.3% homology, the molecular weight probably is about 52800. The CB1 receptor was localised redominantly in the brain, the spinal cord and in the central nervous system.The CB1 receptor mainly distributes in the basis ganglion (opsoninum, pale ball, flank corpus striatum), the seahorse CA cellular layer, the cerebellum and the cerebral cortex.It suggests that the CB1 receptor may be associated with addiction, memory, cognition and motor control regulation. The CB2 receptor is mainly distributed in the peripheral tissue, such as the spleen marginal zone, tonsil, etc. it's distribution may be related to immunosuppression. The recent research have found the CB2 receptor also has the distribution in the central nervous system.At present the function is not clear.It may be related to addiction, depression.
The rewarding effects is various pharmacological basis of drug addiction. The mesencephalon - limbic system (mesolimbic dopamine system, MLDS) is the medicine reward effect neuroanatomy foundation. It is now well-established that opiates and cannabinoids exhibit cross-tolerance and/or mutual potentiation for
antinociception after chronic treatment. It is deduced that CB1 receptor is closely related to morphine addiction, at least in part involved in the process of chronically morphine addiction.Chronic exposure to morphine results in alterations of cannabinoid receptor density is more complex. In the medial caudate nucleus, caudate nucleus and lateral cerebellum reduce the level of CB1 receptor mRNA and protein level increased; in the septal nucleus the CB1 receptor mRNA and the protein level increased; in the nucleus accumbens CB1 receptor protein levels increased ;in the amygdala the level of CB1 receptor protein decreased; in the hippocampus, the dentate gyrus no significant changes in mRNA and protein levels decreased. Nevertheless, the most recent advances in cannabinoid–opioid
cross-modulation have been made in the area of morphine craving and relapse processes.
Compared to lots of studies about the CB1 receptor. However, the neuronal expression of CB2 receptor in the brain and its role in morphine abuse is unknown.
Therefore, we undertook the present study with the aim of investigating, in several brain regions of rats chronically treated with morphine, possible changes of the levels of the CB2 receptor by RT-PCR, Western and immunohistochemistry method. Discussion the distribution and expression of the CB2 receptor in the central nervous system, as well the possible role of the CB2 receptor in morphine addiction.
Morphine induce depression of the immune function, including the inhibition of lymphocyte proliferation, reduce the secretion of cytokines, decreased natural killer cell (NKC) cytotoxicity. Now It been confirmed that activation of CB2 receptors in the peripheral nervous system can induce the formation of IL-4.Thereby affected the transcription of μ opioid receptor. This finding provides the interaction between the endocannabinoids system - opioid system - the immune system. However, there is no evidence of morphine addiction is through CB2 receptors leading to immune suppression. In this study, we will explore the CB2 receptor and morphine addiction related to changes in immune function.
The results showed that (1) Application RT-PCR method to detect the CB1 receptor mRNA expression levels were significantly different in cortex and hippocampus between morphine treated and control rats. (2) Application of western immunoblotting, detected the CB1 receptor protein levels were significantly different in cortex, hippocampus and brain stem between morphine treated and control rats. In the brain stem, although no change in mRNA expression levels, but protein levels increased. (3) Application of immunohistochemistry ,detected the CB1 receptor are widely distributed in in rat cortex, hippocampus, brain stem, cerebellum. (4) Application RT-PCR method to detect the CB2 receptor mRNA expression levels were significantly different in cortex , brain stem and hippocampus between morphine treated and control rats. (5) Application of western immunoblotting, detected the CB2 receptor protein levels were significantly different in cortex, hippocampus and brain stem between morphine treated and control rats. (6) Application of immunohistochemistry ,detected the CB2 receptor are widely distributed in in rat cortex, hippocampus, brain stem, cerebellum. However, significantly less than the number of the CB1 receptor. (7) Application directly ELISA method to detect the chronic morphine dependence and control rats serum, IgM expression decreased; IgG expression increased.
The results suggest that cannabinoid receptors belong to the rhodopsin subfamily of G-protein-coupled receptor superfamily (seven transmembrane domain receptors)
that couple to Gi/Go GTP-binding proteins . Indeed, activation of both types of receptors reduces the cellular levels of cyclic adenosine monophosphate(cAMP) by inhibiting the adenylyl cyclase activity.The stimulation of cannabinoid has been associated with an increase in the activity of mitogen-activated protein kinase pathway and the modulation of potassium conductances through protein kinase C signalling.
Through the above results can be summarized as follows: (1) We verify the CB1 receptor mRNA and protein expression levels were significantly different in cortex and hippocampus between morphine treated and control rats.And the CB1 receptor are widely distributed in in rat cortex, hippocampus, brain stem and cerebellum.So it is likely to play an important role in the process, at least in part involved in the process of chronic morphine addiction.(2) we first confirmed the CB2 receptor mRNA and protein expression levels were significantly different in cortex and hippocampus between morphine treated and control rats.And the CB2 receptor are widely distributed in in rat cortex, hippocampus, brain stem and cerebellum.So it is likely to play an important role in the process, at least in part involved in the process of chronic morphine addiction. (3) We verify the expression of CB1 and CB2 cannabinoid receptors in rat brain tissue indicating that endocannabinoids system may be involved in a broad variety of neurological diseases.It is likely to become a new therapeutic target. (4) We verify compared to the chronic morphine dependence and control rats serum, IgM expression decreased; IgG expression increased. Morphine effects occur through cannabinoid receptor signaling mechanisms and the modulation of cytokines
and other gene products. It appears the immunocannabinoid system is involved in regulating the brain-immune axis and might be exploited infuture therapies for chronic diseases and immune deficiency. |
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