The release of neurotransmitter is regulated in the processes of membrane docking and membrane fusion between synaptic vesicles and presynaptic plasma membranes. Synaptic vesicles contain a diverse set of proteins that participate in these processes. Small GTP-binding proteins exist in the synaptic vesicles and are suggested to play roles for the regulation of neurotransmitter release. We have examined a possible role of GTP-binding proteins in the regulation of protein phosphorylation in the synaptic vesicles. GTPgammaS stimulated the phosphorylation of 46 kappa Da protein (p46) with pI value of 5.0-5.2, but GDPbetaS did not. The p46 was identified as protein interacting with C-kinase 1 (PICK-1) by MALDI-TOF mass spectroscopy analysis, and anti-PICK-1 antibody recognized the p46 spot on 2-dimensional gel electrophoresis. Rab guanine nucleotide dissociation inhibitor (RabGDI), which dissociates Rab proteins from SVs, did not affect phosphorylation of p46. Ca2+/ calmodulin (CaM), which causes the small GTP- binding proteins like Rab3A and RalA to dissociate from the membranes and stimulates CaM- dependnet protein kinase(s) and phosphatase, strongly stimulate the phosphorylation of p46 in the presence of cyclosporin A and cyclophylin. However, RhoGDI, which dissociates Rho proteins from membranes, reduced the phosphorylation of p46 to the extent of about 50%. These results support that p46 was PICK-1, and its phosphorylation was stimulated by GTP and Ca2+/CaM directly or indirectly through GTP-binding protein(s) and Ca2+/CaM effector protein(s). The phosphorylation of p46 (PICK-1) by GTP and Ca2+/CaM may be important for the regulation of transporters and neurosecretion.
Animals ; Calcium/*metabolism ; Calmodulin/*metabolism ; Carrier Proteins/*chemistry/*metabolism ; Guanine Nucleotide Dissociation Inhibitors/metabolism ; Guanosine Triphosphate/metabolism/*pharmacology ; Molecular Weight ; Monomeric GTP-Binding Proteins/metabolism ; Phosphorylation/drug effects ; Rats ; Recombinant Fusion Proteins/*chemistry/*metabolism ; Synaptic Membranes/chemistry/drug effects/*metabolism ; Synaptic Vesicles/chemistry/drug effects/*metabolism

Docosahexaenoic acid(DHA) is a major fatty acid of the gray matter in brain, especially of the synaptic membranes. Modification of membrane fatty acids by dietary fatty acids may influence membrane characteristics and metabolism of neurotransmitters including it's release and reuptake. The effect of w3/w6 fatty acids in maternal diet on the brain neurotransmitters of the offsptings and their behavioral development were investigated in this study. Adult female rats were fed experimental diets with different contents of w3 and w6 fatty acids throughtout pregnancy and lactation and up to 16weekss of pup's age. Experimental diets consisted of 10 wt% fat: cornoil (CO: source of w6, LA), perilla oil (PO: source of w3, a-LNA) and fish oil(FO: source of lonfg chain w3, EPA & DHA). At 3,7 and 16weeks of age, frontal cortex, corpus striatum, thaltmus and cerebellum were dissected out of the whole brain, and the concentrations of 5-hydroxytryptamines(5-HT), catechoamines,and their metabolites were measured by HPLC-ECD. At 16weeks of age, fatty acid compositions of whole brain were determined by GLC. Physical development test in Y-water maze were performed at 15weeks of pup's age. The concentrations of 5-HT in thalamus & hypothalamus was found to be most significiantly correlated with learning ability(r=0.508, p<0.05). At 15weeks of age, the PO group showed higher learning ability compared to the CO or the FO group. Evemn though the DHA level stays rather constant in thhe brain tissue, the ratios of arachidoni c acid(AA,w6)/EPA+DHA(w3) vary significiantly with dietary fatty acids. DHA is known to fulfill very important structural and/or metabolic funtion in membrane system of the brain and AA and its metabolites may also act as transsynaptic messenger and/or second messenger and as the substrate for the production of many biologically active compounds, such as prostaglandins. Therefore, to accomplish full development of brain, proper supply of AA as well as DHA must be considered. Much more studies are needed to clarify th.
Adult ; Animals ; Brain ; Cerebellum ; Corpus Striatum ; Diet ; Fatty Acids* ; Female ; Humans ; Hypothalamus ; Lactation ; Learning ; Membranes ; Metabolism ; Neurotransmitter Agents* ; Perilla ; Pregnancy ; Prostaglandins ; Rats* ; Second Messenger Systems ; Serotonin ; Synaptic Membranes ; Thalamus

OBJECTIVETo study the possible mechanism of aqueous extract of detoxified cottonseeds (CTN-W).

METHOD AND RESULTCTN-W 0.01, 0.03, 0.10, 0.30 mg.mL-1 was incubated directly with the synaptic membrane extracted from the cerebral cortex in rats, and adenylyl cyclase (AC) activity was detected by using radio-immunoassay.

RESULTShowed that CTN-W could activate AC in a dose-dependend manner. After incubation with PC12 cells in the presence of corticosterone 2 x 10(-4)mol.L-1 for 48 h, CTN-W 0.08, 0.4, 2 mg.mL-1 protected PC12 cells from the lesion induced by corticosterone.

CONCLUSIONAntidepressant and anxiolytic effects of CTN-W are related with the activation of AC-cAMP pathway in signal transduction system, thus protecting neurons from the lesion. These two aspects maybe partly form the mechanism of CTN-W's action.

Adenylyl Cyclases ; metabolism ; Animals ; Anti-Anxiety Agents ; pharmacology ; Antidepressive Agents ; pharmacology ; Corticosterone ; antagonists & inhibitors ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Gossypium ; chemistry ; Neuroprotective Agents ; pharmacology ; PC12 Cells ; drug effects ; Plants, Medicinal ; chemistry ; Rats ; Rats, Wistar ; Seeds ; chemistry ; Synaptic Membranes ; enzymology

Low molecular weight GTP-binding proteins are molecular switches that are believed to play pivotal roles in cell growth, differentiation, cytoskeletal organization, and vesicular trafficking. Rab proteins are key players in the regulation of vesicular transport, while Rho family members control actin-dependent cell functions, i.e. the regulation of cytoskeletal organization in response to extracelluar growth factors and in dendritic neuron development. In this study, we have examined the regulation of small GTP-binding proteins that are implicated in neurosecretion and differentiation of neuron during ageing processes. Comparison of small GTP-binding proteins from the synaptosome and crude synaptic vesicles (LP2 membranes) of 2 months and 20 months old rat brain respectively showed no difference in the level of Rab family proteins (Rab3A and Rab5A). However, Rho family proteins such as RhoA and Cdc42 were elevated in LP2 membranes of the aged brain. The dissociation of Rab3A by Ca2+/calmodulin (CaM) from SV membranes was not changed during aging. Ca2+/CaM stimulated phosphorylation of the 22 and 55-kDa proteins in SV membranes from the aged rat brain, and inhibited phosporylation of 30-kDa proteins. GTPgammaS inhibited phosphorylation of the 100-kDa proteins and stimulated phosphorylation of the 70 kDa in LP2 membranes from both the young and aged rat brains, whereas GDPbetaS caused just the opposite reaction. These results suggest that protein phosphorylation and regulation of Rho family GTPases in rat brain appears to be altered during ageing processes.
*Aging ; Animal ; Brain/metabolism ; Calcium/pharmacology ; Cattle ; Comparative Study ; GTP-Binding Proteins/*metabolism ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Molecular Weight ; Phosphorylation/drug effects ; Rats ; Rats, Sprague-Dawley ; Synaptic Membranes/*metabolism ; Synaptosomes/*metabolism ; cdc42 GTP-Binding Protein/biosynthesis/metabolism ; rab3A GTP-Binding Protein/metabolism ; rab5 GTP-Binding Proteins/metabolism ; rhoA GTP-Binding Protein/biosynthesis/metabolism

Low molecular weight GTP-binding proteins are molecular switches that are believed to play pivotal roles in cell growth, differentiation, cytoskeletal organization, and vesicular trafficking. Rab proteins are key players in the regulation of vesicular transport, while Rho family members control actin-dependent cell functions, i.e. the regulation of cytoskeletal organization in response to extracelluar growth factors and in dendritic neuron development. In this study, we have examined the regulation of small GTP-binding proteins that are implicated in neurosecretion and differentiation of neuron during ageing processes. Comparison of small GTP-binding proteins from the synaptosome and crude synaptic vesicles (LP2 membranes) of 2 months and 20 months old rat brain respectively showed no difference in the level of Rab family proteins (Rab3A and Rab5A). However, Rho family proteins such as RhoA and Cdc42 were elevated in LP2 membranes of the aged brain. The dissociation of Rab3A by Ca2+/calmodulin (CaM) from SV membranes was not changed during aging. Ca2+/CaM stimulated phosphorylation of the 22 and 55-kDa proteins in SV membranes from the aged rat brain, and inhibited phosporylation of 30-kDa proteins. GTPgammaS inhibited phosphorylation of the 100-kDa proteins and stimulated phosphorylation of the 70 kDa in LP2 membranes from both the young and aged rat brains, whereas GDPbetaS caused just the opposite reaction. These results suggest that protein phosphorylation and regulation of Rho family GTPases in rat brain appears to be altered during ageing processes.
*Aging ; Animal ; Brain/metabolism ; Calcium/pharmacology ; Cattle ; Comparative Study ; GTP-Binding Proteins/*metabolism ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Molecular Weight ; Phosphorylation/drug effects ; Rats ; Rats, Sprague-Dawley ; Synaptic Membranes/*metabolism ; Synaptosomes/*metabolism ; cdc42 GTP-Binding Protein/biosynthesis/metabolism ; rab3A GTP-Binding Protein/metabolism ; rab5 GTP-Binding Proteins/metabolism ; rhoA GTP-Binding Protein/biosynthesis/metabolism