The mechanism of morphine dependent is a complex Procedure. It involves in many complex mechanisms such as the ultra-structure of synapse of special brain areas, neurotransmitter, enzymology, and so on. These mechanisms have closely correlation. In this paper we reveiwed the development in enzymological mechanism of morphine dependent enzymes including protein kinase (PK), nitric oxide synthase (NOS), superoxide dismutase (SOD), adenylate cyclase (AC), Succinate dehydrogenase (SDH)and 3beta-Hydroxy steroid dehydrogenase (3beta-HSD).
Adenylyl Cyclases/metabolism* ; Animals ; Brain/enzymology* ; Morphine Dependence/pathology* ; Nitric Oxide Synthase/metabolism* ; Protein Kinases/metabolism* ; Substance Withdrawal Syndrome/metabolism* ; Succinate Dehydrogenase/metabolism* ; Superoxide Dismutase/metabolism* ; Synapses/enzymology*

OBJECTIVETo study the toxicity of methomyl to acetylcholinesterase (AChE) in different regions.

METHODSThe optimal temperature and time for measurement of AChE activity were determined in vitro. The dose- and time-response relationships of methomyl with AChE activity in human erythrocyte membrane, rat erythrocyte membrane, cortical synapses, cerebellar synapses, hippocampal synapses, and striatal synapses were evaluated. The half maximal inhibitory concentration (IC50) and bimolecular rate constant (K) of methomyl for AChE activity in different regions were calculated, and the type of inhibition of AChE activity by methomyl was determined.

RESULTSAChE achieved the maximum activity at 370 °C, and the optimal time to determine initial reaction velocity was 0-17 min. There were dose- and time-response relationships between methomyl and AChE activity in the erythrocyte membrane and various brain areas. The IC50 value of methomyl for AChE activity in human erythrocyte membrane was higher than that in rat erythrocyte membrane, while the Ki value of methomyl for AChE activity in rat erythrocyte membrane was higher than that in human erythrocyte membrane. Among synapses in various brain areas, the striatum had the highest IC50 value, followed by the cerebellum, cerebral cortex, and hippocampus, while the cerebral cortex had the highest Ki value, followed by the hippocampus, striatum, and cerebellum. Lineweaver-Burk diagram demonstrated that with increasing concentration of methomyl, the maximum reaction velocity (Vmax) of AChE decreased, and the Michaelis constant (Km) remained the same.

CONCLUSIONMethomyl is a reversible non-competitive inhibitor of AChE. AChE of rat erythrocyte membrane is more sensitive to methomyl than that of human erythrocyte membrane; the cerebral cortical synapses have the most sensitive AChE to methomyl among synapses in various brain areas.

Acetylcholinesterase ; metabolism ; Animals ; Cerebellum ; drug effects ; Cerebral Cortex ; drug effects ; Erythrocyte Membrane ; drug effects ; enzymology ; Hippocampus ; drug effects ; Humans ; Inhibitory Concentration 50 ; Methomyl ; toxicity ; Rats ; Synapses ; drug effects ; Toxicity Tests

This study is to explore the possible mechanisms of the antidepressant-like effect of agmatine. By using two traditional "behavior despair" model, tail suspension test and forced swimming test, we examined the effects of some monoamine receptor antagonists (including beta-adrenergic receptor antagonist propranolol, beta-adrenergic receptor antagonist/5-HT1A/1B receptor antagonist pindolol, alpha2-adrenergic receptor antagonists yohimbine and idazoxan and 5-HT3 receptor antagonist tropisetron) on the antidepressant-like action of agmatine in mice. Activity of adenylate cyclase (AC) in the synapse membrane from rat frontal cortex was determined by radioimmunoassay. Single dose of agmatine (5-40 mg x kg(-1), ig) dose-dependently decrease the immobility time in tail suspension test in mice, indicating an antidepressant-like effect. The effect of agmatine (40 mg x kg(-1), ig) was antagonized by co-administration of beta-adrenergic receptor antagonist/5-HT1A/1B receptor antagonist pindolol (20 mg x kg(-1), ip), alpha2-adrenergic receptor antagonists yohimbine (5-10 mg x kg(-1), ip) or idazoxan (4 mg x kg(-1), ip), but not beta-adrenergic receptor antagonist propranolol (5-20 mg x kg(-1), ip) and 5-HT3 receptor antagonist tropisetron (5-40 mg x kg(-1), ip). Agmatine (5-40 mg x kg(-1), ig) also dose-dependently decrease the immobility time in forced swimming test in mice. The effect of agmatine (40 mg x kg(-1), ig) was also antagonized by pindolol (20 mg x kg(-1), ip), yohimbine (5-10 mg x kg(-1), ip), or idazoxan (4 mg x kg(-1), ip). Incubation of agmatine (0.1-6.4 micromol x L(-1)) with the synaptic membrane extracted from rat frontal cortex activated the AC in a dose-dependent manner in vitro. While the effect of agmatine (6.4 micromol x L(-1)) was dose-dependently antagonized by pindolol (1 micromol x L(-1)) or yohimbine (0.25-1 micromol x L(-1)). Chronic treatment with agmatine (10 mg x kg(-1), ig, bid, 2 w) or fluoxetine (10 mg x kg(-1), ig, bid, 2 w) increased the basic activity, as well as the Gpp (NH)p (1-100 micromol x L(-1)) stimulated AC activity in rat prefrontal cortex. These results indicate that regulation on 5-HT1A/1B and alpha2 receptors, and activation AC in the frontal cortex is one of the important mechanisms involving in agmatine's antidepressant-like action.
Adenylyl Cyclases ; metabolism ; Adrenergic alpha-Antagonists ; pharmacology ; Adrenergic beta-Antagonists ; pharmacology ; Agmatine ; administration & dosage ; pharmacology ; Animals ; Antidepressive Agents ; administration & dosage ; pharmacology ; Behavior, Animal ; drug effects ; Depression ; metabolism ; physiopathology ; Dose-Response Relationship, Drug ; Fenclonine ; pharmacology ; Idazoxan ; pharmacology ; Male ; Mice ; Pindolol ; pharmacology ; Random Allocation ; Rats ; Rats, Wistar ; Receptors, Biogenic Amine ; antagonists & inhibitors ; Serotonin 5-HT1 Receptor Antagonists ; Swimming ; Synapses ; enzymology ; Yohimbine ; pharmacology

OBJECTIVETo examine modulations caused by cyclooxygenase-2 (COX-2) inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possible mechanisms.

METHODSCelecoxib (a COX-2 inhibitor) was administered 45 min prior to pilocarpine administration. The effects of COX-2 inhibitors on mIPSCs (miniature GABAergic inhibitory postsynaptic currents) of CA3 pyramidal cells in the hippocampus were recorded. Expressions of COX-2, c-Fos, newly generated neurons, and activated microgliosis were analyzed by immunohistochemistry, and expressions of alpha-subunit of gamma-amino butyric acid (GABA(A)) receptors and mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) activity were detected by Western blotting.

RESULTSPretreatment with celecoxib showed protection against pilocarpine-induced seizures. Celecoxib prevented microglia activation in the hilus and inhibited the abnormal neurogenesis and astrogliosis in the hippocampus by inhibiting MAPK/ERK activity and c-Fos transcription. Celecoxib also up-regulated the expression of GABA(A) receptors. NS-398 (N-2-cyclohexyloxy-4-nitrophenyl-methanesulfonamide), another COX-2 inhibitor, enhanced the frequency and decay time of mIPSCs.

CONCLUSIONThe COX-2 inhibitor celecoxib decreased neuronal excitability and prevented epileptogenesis in pilocarpine-induced status epilepticus rats. Celecoxib regulates synaptic reorganization by inhibiting astrogliosis and ectopic neurogenesis by attenuating MAPK/ERK signal activity, mediated by a GABAergic mechanism.

Animals ; Blotting, Western ; Celecoxib ; Cyclooxygenase 2 ; metabolism ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Disease Models, Animal ; Fibrocystic Breast Disease ; metabolism ; Hippocampus ; drug effects ; enzymology ; pathology ; Immunohistochemistry ; MAP Kinase Signaling System ; drug effects ; Male ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; Nitrobenzenes ; pharmacology ; Pilocarpine ; Proto-Oncogene Proteins c-fos ; metabolism ; Pyrazoles ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-A ; biosynthesis ; Status Epilepticus ; chemically induced ; enzymology ; pathology ; Sulfonamides ; pharmacology ; Synapses ; drug effects ; pathology