The purpose of this study was to investigate the effects of α₂ adrenergic receptor agonist dexmedetomidine on withdrawal symptoms in alcohol-dependent rats and the underlying mechanism, so as to provide a scientific basis for the treatment of alcohol withdrawal syndrome (AWS). Adult Sprague-Dawley (SD) male rats were orally administered with 6% aqueous alcohol continuously for 28 d to establish alcohol drinking model, and then stopped drinking to induce AWS. Enzyme-linked immunosorbent assay (ELISA) was used to determine the content of norepinephrine (NE) in the locus coeruleus and hippocampus of rats. Dexmedetomidine (5, 10, and 20 μg/kg) was intraperitoneally injected respectively when the rats showed significant AWS. In some rats, α₂ adrenergic receptor antagonist yohimbine was injected into hippocampus in advance. The results showed that, compared with the control group, the 6 h withdrawal group exhibited significantly increased AWS score and amount of repeat drinking. The NE contents in hippocampus and locus coeruleus of the last drinking and the 6 h withdrawal groups were significantly increased compared with those of the control group. Dexmedetomidine intervention significantly decreased AWS score and hippocampus NE content in the 6 h withdrawal group, while yohimbine could reverse these effects of dexmedetomidine. These results suggest that dexmedetomidine might improve the withdrawal symptoms in alcohol-dependent rats via activating α₂ adrenergic receptor.
Adrenergic alpha-2 Receptor Agonists/therapeutic use* ; Alcoholism/drug therapy* ; Animals ; Dexmedetomidine/therapeutic use* ; Hippocampus/metabolism* ; Male ; Norepinephrine ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, alpha-2/metabolism* ; Substance Withdrawal Syndrome/drug therapy* ; Yohimbine/pharmacology*

OBJECTIVE: To observe the protein expression of growth associated protein-43 (GAP-43) in midbrain ventral tegmental area in morphine withdrawal rats at different time, and to evaluate the effect of GAP-43 on morphine withdrawal memory. METHODS: Rat models of morphine dependent 1 week, 2 weeks and 4 weeks were established by morphine hydrochloride intraperitoneal injection with increasing doses to establish natural withdrawal. The protein expression of GAP-43 in midbrain ventral tegmental area was observed by immunohistochemical staining and the results were analyzed by Image-Pro Plus 5.1 image analysis system. RESULTS: With prolongation of dependent time, the expression of GAP-43 was decreased then increased in midbrain ventral tegmental area. CONCLUSION GAP-43 could play a role in morphine withdrawal memory in midbrain ventral tegmental area.
Animals ; Behavior, Animal/drug effects* ; Disease Models, Animal ; Female ; GAP-43 Protein/metabolism* ; Immunohistochemistry ; Male ; Mesencephalon/metabolism* ; Morphine/adverse effects* ; Morphine Dependence/metabolism* ; Naloxone/pharmacology* ; Rats ; Rats, Sprague-Dawley ; Substance Withdrawal Syndrome/metabolism* ; Time Factors ; Ventral Tegmental Area/metabolism*

Adult rats were implanted with sleep-wake recording electrodes in our experiments. Polygraphic signs of undisturbed sleep-wake activities were recorded for 24 h before cocaine administration, cocaine withdrawal day 1 (acute), day 8 (subacute), and day 14 (subchronic). Western blot method was performed to examine the expression levels of adenosine receptor subtypes in hypothalamus and cerebellum. Non rapid eye movement (NREM) sleep was significantly increased during nighttime (P < 0.01) and daytime (P < 0.05) on withdrawal day 8. The increase of NREM sleep was significant during nighttime (P < 0.01) and slight during daytime on withdrawal day 14, whereas both daytime and nighttime rapid eye movement (REM) sleeps were reduced markedly (P < 0.01) on withdrawal day 8 and 14. In addition, A2A receptor level was significantly enhanced on cocaine withdrawal day 8 and day 14 (P < 0.05), whereas A1 receptor level reduced markedly on withdrawal day 14 (P < 0.05). However, compared with that in the control group, no significant changes existed among adenosine A1, A2A and A2B receptors in rat cerebellum on cocaine withdrawal day 1, day 8 and day 14. Our findings suggest that sleep disorder caused by subacute and subchronic cocaine abstinence may be associated with over-expression of adenosine A2A receptor in rat hypothalamus to some extent.
Animals ; Cocaine ; adverse effects ; Dyssomnias ; chemically induced ; Electroencephalography ; Hypothalamus ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Receptor, Adenosine A2A ; metabolism ; Substance Withdrawal Syndrome

OBJECTIVETo explore the effects of intrathecal injection of neuronal nitric oxide synthase (nNOS) inhibitors 7-Nitroindazole (7-Ni) and inducible nitric oxide synthase(iNOS) inhibitors aminoguanidine (AG) on the behavioral changes of morphine-induced dependent and withdrawal rats; the expression of Fos, nNOS and iNOS in spinal cord.

METHODSTo set up morphine dependence model, rats were subcutaneously injected with morphine (twice a day, for 5 d). The dose of morphine was 10 mg/kg in the first day and was increased by 10 mg/ kg every day. On day 6, 4 h after the injection of morphine (50 mg/kg), morphine withdrawal syndrome was precipitated by an injection of naloxone (4 mg/kg ip). 7-Ni, an nNOS inhibitor or iNOS inhibitors AG were intrathecally injected 30 min before the administration of naloxone respectively. The scores of morphine withdrawal symptom and morphine withdrawal-induced allodynia were observed. One hour after naloxone-precipitated withdrawal, Fos protein expression was assessed by immunohistochemical analysis and Western blot was used to detect the expression of nNOS and iNOS in the rat spinal cord.

RESULTSIntrathecal administration of nNOS inhibitor 7-Ni and iNOS inhibitors AG decreased the scores of morphine withdrawal, attenuated morphine withdrawal-induced allodynia and also inhibited the increase of Fos protein expression in the spinal cord of morphine withdrawal rats. nNOS and iNOS positive neurons in dorsal horn in nNOS group and iNOS group were significantly lower than that in withdrawal group. Compared with withdrawal group, level of nNOS and iNOS protein in spinal cord in nNOS group and iNOS group were significantly lower.

CONCLUSIONIt is suggested that nNOS and iNOS in the spinal cord may contribute to naloxone-precipitated withdrawal in rats and may play different roles in the above-mentioned effect.

Animals ; Guanidines ; pharmacology ; Indazoles ; pharmacology ; Male ; Morphine Dependence ; metabolism ; Naloxone ; pharmacology ; Nitric Oxide Synthase Type I ; antagonists & inhibitors ; metabolism ; Nitric Oxide Synthase Type II ; antagonists & inhibitors ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; drug effects ; metabolism ; Substance Withdrawal Syndrome ; metabolism

OBJECTIVETo explore if induced nitric oxide in the spinal cord mediates withdrawal syndrome in morphine-dependent rats.

METHODSMale SD rats weighing 200-250 g were employed in the present study. To set up morphine dependence model, rats were subcutaneously injected with morphine (twice a day, for 5 d). The dose of morphine was 10 mg/kg in the first day and was increased by 10 mg/kg each day. On day 6, 4 h after the injection of morphine (50 mg/kg), morphine withdrawal syndrome was precipitated by an injection of naloxone (4 mg/kg, ip). Inducible nitric oxide synthase (iNOS) inhibitors aminoguanidine (AG) was intrathecally injected 30 min before the administration of naloxone. All the rats were divided into four groups: control group, dependence group, withdrawal group, AG group. Morphine withdrawal score, touch evoked agitation scores (TEA scores), immunohistochemical and Western blot technique were used to evaluate morphine withdrawal response and the expression of iNOS in the spinal cord.

RESULTSIntrathecal injection of iNOS inhibitors AG could alleviate morphine withdrawal symptoms. Morphine withdrawal scores and touch evoked agitation scores in AG group were significantly lower than that of withdrawal group (P < 0.05). iNOS positive neurons in dorsal horn of AG group were significantly lower than that of withdrawal group (P < 0.05). Level of iNOS protein in spinal cord of AG group was significantly lower than that of withdrawal group (P < 0.05).

CONCLUSIONInduced nitric oxide in the spinal cord may mediate withdrawal syndrome in morphine-dependent rats.

Animals ; Male ; Morphine Dependence ; metabolism ; Naloxone ; pharmacology ; Nitric Oxide Synthase Type II ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; metabolism ; Substance Withdrawal Syndrome ; metabolism

The previous study indicated that aquaporin 4 (AQP4) deficiency attenuated opioid physical dependence. However, the underlying mechanism remains unknown. In the present study, the effects of AQP4 deficiency on the expression of three factors, protein kinase C (PKC) α, PKCγ and c-Fos in the spinal cord, which are known to be concerned with spinal neuronal sensitization and opiate dependence, were investigated in AQP4 knockout mice using Western blotting analysis. It was observed that AQP4 deficiency reduced the score of naloxone-precipitated abstinent jumping after repeated morphine administration compared with wild-type (P < 0.001). Meanwhile, the protein levels of PKCα and c-Fos in the spinal cord of AQP4 knockout mice were significantly higher than those in the wild-type mice; while the expression of PKCγ was decreased remarkably by AQP4 knockout during the withdrawal (P < 0.01). These data suggest that AQP4 deficiency-attenuated morphine withdrawal responses may be partially attributed to the changes in the spinal expression of PKCα, PKCγ or c-Fos.
Analgesics, Opioid ; pharmacology ; Animals ; Aquaporin 4 ; deficiency ; genetics ; Mice ; Mice, Knockout ; Morphine ; pharmacology ; Naloxone ; pharmacology ; Protein Kinase C ; metabolism ; Protein Kinase C-alpha ; metabolism ; Spinal Cord ; metabolism ; Substance Withdrawal Syndrome ; metabolism

OBJECTIVETo investigate the effects of purine nucleotide on the expressions of follicle-stimulating hormone (FSH) and luteotrophic hormone (LH) and the ultrastructures of the distal somatotrophic and gonadotrophic cells in the pituitary gland of heroin-addicted and -withdrawal rats.

METHODSNinety-two male Wistar rats were randomly divided into a control group (ip saline for 14 d), a nucleotide group (ip AMP and GMP for 10 d), a heroin group (ip heroin for 10 d), a heroin + nucleotide group (ip AMP and GMP + heroin for 10 d), a 3 d withdrawal group (ip heroin for 10 d and killed at 14 d), a 9 d withdrawal group (ip heroin for 10 d and killed at 20 d), a 3 d nucleotide group (ip nucleotide for 3 d after 10 d heroin administration and killed at 14 d), and a 9 d nucleotide group (ip nucleotide for 9 d after 10 d heroin administration and killed at 20 d). Changes in the mRNA expressions of FSH and LH in the pituitary gland of the rats were analyzed by semi-quantitative RT-PCR, and alterations in the ultrastructures of the distal somatotrophic and gonadotrophic cells were observed under the microscope.

RESULTSThe expression of FSH mRNA was significantly increased in the nucleotide, heroin + nucleotide, 3 d nucleotide and 9 d nucleotide groups (0.099 +/- 0.018, 0.177 +/- 0.046, 0.151 +/- 0.030 and 0.184 +/- 0.028) as compared with the control group (0.045 +/- 0.009) (P < 0.01); and so was that of LH mRNA in the heroin + nucleotide, 3 d nucleotide and 9 d nucleotide groups (0.950 +/- 0.169, 0.990 +/- 0.171 and 0.960 +/- 0.147) in comparison with the control group (0.700 +/- 0.099) (P < 0.01). In the heroin group, the nuclei of the distal somatotrophic and gonadotrophic cells exhibited morphological abnormality, unclear membrane, slightly pyknotic matrix, marginal and agglutinated heterochromatin, dilated rough endoplasmic reticula, swollen mitochondria, broken and vacuolated cristae in the cytoplasm, obviously decreased number of secretory granules, and myelin bodies in some cells. However, the heroin + nucleotide group showed no significant changes in the ultrastructures of somatotrophic and gonadotrophic cells compared with the control group.

CONCLUSIONShort-term use of heroin does not obviously affect the expressions of FSH and LH mRNA in the pituitary gland of rats, while heroin + nucleotide, or nucleotide following heroin withdrawal can enhance their expressions significantly. Heroin damages the ultrastructures of the distal somatotrophic and gonadotrophic cells in the pituitary gland of male rats, and purine nucleotide can diminish or inhibit this damage.

Animals ; Follicle Stimulating Hormone ; genetics ; metabolism ; Gene Expression ; drug effects ; Heroin ; adverse effects ; Heroin Dependence ; genetics ; metabolism ; Luteinizing Hormone ; genetics ; metabolism ; Male ; Pituitary Gland ; drug effects ; metabolism ; ultrastructure ; Purine Nucleotides ; pharmacology ; Rats ; Rats, Wistar ; Substance Withdrawal Syndrome ; genetics ; metabolism

OBJECTIVETo explore the effects of intrathecal injection of mitogen-activated protein kinases inhibitors U0126 on the behavioral changes of morphine-induced dependent and withdrawal rats and the expression of nitric oxide synthase (NOS) in spinal cord.

METHODSAll the rats were divided into 4 groups: control group, dependent group, withdrawal group, U0126 group (5 microg). Global withdrawal score, Touch evoked agitation scores (TEA score), immunohistochemical and Western blot technique were undertaken to evaluate behavioral changes and expression of FOS, nNOS and iNOS in spinal cord respectively.

RESULTSThe results showed that intrathecal administration of U0126 significantly alleviated withdrawal symptom, withdrawal scores of U0126 group (22.5 +/- 4.09) were significantly lower than than those of withdrawal group (28.6 +/- 4.89) (P < 0.05). TEA scores of withdrawal group were 13.5 +/- 2.55, which were significantly higher than those of U0126 group (10.0 +/- 2.76, P < 0.05). Fos-like positive neurons in dorsal horn of withdrawal group were 380 +/- 71, which were higher than those of U0126 group(287 +/- 54, P < 0.05). Also nNOS and iNOS positive neurons in dorsal horn of U0126 group were 180 +/- 32, 10.8 +/- 2.8 respectively, which were significantly lower than that of withdrawal group (239 +/- 45, 16.8 +/- 5.1, P < 0.05). Compared with withdrawal group, levels of nNOS and iNOS protein in spinal cord of U0126 group were significantly lower.

CONCLUSIONMEK inhibitors could alleviate withdrawal symptom of morphine-induced dependent rats and could suppress expression of NOS in spinal cord, and extracellular signal-regulate kinase (ERK) might involve the expression of NOS in spinal cord.

Animals ; Behavior, Animal ; drug effects ; Butadienes ; pharmacology ; Enzyme Inhibitors ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Male ; Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; Morphine ; adverse effects ; Morphine Dependence ; metabolism ; Nitric Oxide Synthase ; metabolism ; Nitriles ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; metabolism ; Substance Withdrawal Syndrome ; metabolism

Actins ; metabolism ; Animals ; Male ; Morphine ; adverse effects ; Morphine Dependence ; metabolism ; Prefrontal Cortex ; metabolism ; Proteome ; metabolism ; Rats ; Rats, Sprague-Dawley ; Substance Withdrawal Syndrome ; metabolism ; Synaptosomal-Associated Protein 25 ; metabolism

OBJECTIVETo investigate the effects of clobenpropit and histidine on reinstatement of morphine-induced conditioned place preference (CPP) in rats.

METHODSThe persistence, extinction and reinstatement of morphine-induced CPP were established.In clobenpropit group three different doses of clobenpropit (2, 5 and 10 microg/rat, i.c.v.) were administered 15 min after morphine (1 mg/kg, i.p.) was injected. In histidine group histidine (100, 200, 500 mg/kg) was given 1 h prior to morphine treatment (1 mg/kg i.p).

RESULTThe CPP was reinstated by priming injection of 1 mg/kg morphine. Clobenpropit (5, 10 microg/rat) significantly inhabited the reinstatement by a priming dose of morphine-induced CPP compared with the morphine control group; histidine (100, 200, 500 mg/kg) significantly inhibited the reinstatement in a dose-dependent manner.

CONCLUSIONClobenpropit and histidine inhibit the revival of morphine-induced CPP in a dose dependent manner, indicating that endogenous histamine may inhibit relapse of morphine to some extent.

Animals ; Conditioning, Operant ; drug effects ; Histidine ; metabolism ; Imidazoles ; pharmacology ; Male ; Morphine Dependence ; physiopathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Cell Surface ; antagonists & inhibitors ; Substance Withdrawal Syndrome ; physiopathology ; Thiourea ; analogs & derivatives ; pharmacology