摘要:

Abstract–Adenosine 3′,5′‐cyclic monophosphate (cyclic AMP) levels increase about 5‐fold in the cerebral cortex and 2‐fold in the cerebellum following electroconvulsive shock (ECS). The peak levels of cyclic AMP occur at 45 s after ECS in the cerebral cortex, and at 15 s in the cerebellum. In the cerebral cortex, ECS produces twice the cyclic AMP accumulation as does decapitation in a comparable time period; however, the relative effect of a number of neurotropic agents on the cyclic AMP accumulation is essentially the same, whether stimulated by decapitation or by ECS. In the cerebellum, the levels of guanosine 3′,5′‐cyclic monophosphate (cyclic GMP) also increase following ECS. The cyclic GMP levels are greatest at 60 s after ECS during the postictal depression. An association between elevated cerebellar cyclic GMP and depression seems unlikely, since CNS depressants either lowered or had no effect on cyclic GMP levels. From these results, cyclic nucleotide profiles following treatments such as ECS or decapitation may be useful in elucidating the molecular events involved in seizures, brain in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04427.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The accumulation of adenosine‐3′,5′‐cyclic monophosphate (cyclic AMP) has been investigated in murine brain following electroconvulsive shock and decapitation. Animals were made hypothermic (20°C) to minimize the freezing time of the brain and to delay metabolic events. Cyclic AMP concentrations were decreased in the cerebral cortex of hypothermic rats and mice. Furthermore, the changes in cyclic AMP elicited by electroconvulsive shock and decapitation were delayed. In hypothermic animals, the metabolic rate as determined by high energy phosphate use was decreased to 65% of control values. The interconversions of the active and inactive forms of glycogen phosphorylase and glycogen synthase were sufficiently retarded in hypothermic animals to correlate with changes in cyclic AMP concentrations. The conversion of phosphorylase b to a and synthase a to b occurred when cyclic AMP concentrations had increased from 2 to 5 μmol/kg, following either electroconvulsive shock or decapitation. The results indicate that cyclic AMP plays a role in regulation of glycogen metabolism in cere

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04428.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The activities of sRNA‐aminoacyl synthetases (EC 6.1.1) were investigated in the cerebral white and grey matter of rabbits subjected during their prenatal life to a single X‐ray dose of 150 rad. The results of investigations have shown that ionizing radiation acting during intrauterine development of the experimental animal brings about a distinct depression of all sRNA‐aminoacyl synthetase activities in the newborn irradiated litter. During the postnatal development of these animals the activities of some of the synthetases further decreased and even at adulthood, where they are normally very low, their activities were below the control values. The activities of some other synthetases, after the initial depression, showed no further decrease and at adulthood had values comparable to controls. Our results indicate clearly that prenatal exposure to ionizing radiation also affects the step of protein biosynthesis which depends on the activity of sRNA‐aminoacyl sy

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04429.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Protein synthesis in an identified molluscan neurosecretory cell of the landsnail, Otala lacteawas examined using three different types of polyacrylamide gel electrophoresis. Cells taken from active snails synthesized specific low molecular weight proteins while those from aestivated snails did not. Most of the newly synthesized low molecular weight proteins in the active snails were lost from the cell body when the preparations was chased for 19 h in label‐free enriched medium in the presence of anisomycin, an inhibitor of protein synthesis. If colchicine, a blocker of axonal transport, was included in the chase medium, the proteins present following a pulse were largely replaced by smaller molecular weight species. The results suggest that specific low molecular weight proteins are converted to smaller species and then transported from the cell b

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04430.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The effect of short (4–6 min)‘pulses’ of elevated extracellular potassium ionsK0, in the 10–50 mmrange, on the efflux of [3H]norepinephrine [3H]NE) and [14C]α‐aminoisobutyrate (AIB) has been studied in a superfused neocortical thin slice system. At all the concentrations tested highK0increases the efflux of both NE and AIB, although thc effects on the former are greater. In the absence of calcium ions, or in the presence of 8 mm‐MnCl2, the potassium‐stimulated release of both NE and AIB is severely depressed. However, potassium induced NE release is proportional to extracellular calcium ions in the 0–1.5 mmrange, while that of AIB does not continue to increase above 0.2 mm‐calcium. This permissive role of calcium in amino acid efflux is interpreted as due to changes in the inactivation of membran

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04431.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Administration of cycloheximide, 10 mg/kg s.c. led within 4 h to an approx 30% reduction of dopamine‐β‐hydroxylase (DBH) activity in the abdominal portion of rat sciatic nerves. At least two more hours elapsed before DBH activity in the distal part of these nerves began to fall. This pattern suggests reduced synthesis or delivery of DBH into axons but continued transport of previously delivered enzyme. Coinciding with the time at which DBH activity began to fall in distal segments of sciatic nerve, there was a marked reduction in the accumulation of DBH activity above a ligature in this region. Between 4 and 8 h after administration of cylcoheximide, 10 mg/kg, accumulation above a ligature was 70% less than in untreated nerves (P<0.001), a reduction significantly greater (P<0.05) than the accompanying 28% loss of baseline DBH activity. At the same time, the clearance of DBH activity from nerve regions distal to a ligature was greatly reduced. This pattern is consistent with the depletion of a minor but rapidly transported compartment of DBH. Six hours after administration of cylcoheximide, 10 mg/kg, the apparent subcellular distribution of DBH in distal regions of sciatic nerve was altered by a significant 36% loss in sedimentable DBH activity, with non‐significant changes in othcr fractions. This suggests that rapidly transported DBH, depleted from the nerve by cycloheximide‐induced inhibition of protein synthesis, is more highly associated with intraneuronal particles than is slowly transported or stat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04432.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Neuronal and oligodendroglial cell fractions isolated from trypsinized brain contain trypsin. Neuronal cell bodies contained approximately 5μg of trypsin/mg of cell protein; oligodendroglial cells had approx 1μg of enzyme activity. Studies with fluorescein‐conjugated trypsin suggested that least a portion of the fluorescent enzyme was internalized in ne

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04433.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract–Mammalian brain contains 2N‐acylamino acid amidohydrolases resembling the respective kidney enzymes. The anatomical and subcellular distribution of the enzymes; the substrate specificities and interspecies activities of the partially purified amidohydrolases have been studied. A considerable proportion of the amidohydrolase activity of subcellular fractions was found to be associated with the paniculate matter. The increased activities of the particulate enzymes in the presence of Triton X‐100 and chloroacetyl amino acid substrates suggest that significant amounts of the enzymes are in the bound or latent

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04434.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Rat pineal serotoninN—acetyltransferase activity increases 30–70‐fold at night in the dark and then decreases rapidly when animals are exposed to light. Activity of the enzyme is also stimulated byl‐norepinephrine in organ culture. When homogenates of glands stimulated by darkin vivoor NEin vitroare incubated at 37°C, enzyme activity will also rapidly decrease. This decrease can be prevented by one of the cosubstrates of the enzyme, acetyl–CoA. Protection can also be conferred by cysteamine (β‐mercaptoethylamine, HS–CH2–CH2–NH2) which is the terminal portion of the CoA molecule. This protection mechanism could be involved in the physiological contr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04435.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Measurements of the incorporation of [14C]NaHCO3into orotic acid, uridine nucleotides and RNA in tissue minces establish the occurrence of the complete orotate pathway for thede novobiosynthesis of pyrimidines in rat brain. Selective inhibition of the incorporation of various radiolabelled precursors into orotic acid by uridine demonstrates the operation of a feedback control mechanism in brain minces and indicates carbamoylphosphate synthetase to be the site of inhibition; purine nucleosides were similarly found to inhibit thede novobiosynthesis of pyrimidines.The activity of the orotate pathway, as assessed by the rate of incorporation of [14C]NaHCO3into orotic acid, was found to be very high in fetal brain and to decline rapidly with neurological development; the mature rat brain exhibits less than 1% of the activity of the fetal brain at 18 days of gestation. Comparative studies on the ability of minces of the brain and several extraneural tissues to utilize [14C]NaHCO3and [14C]aspartate as precursors of orotic acid lead us to speculate that variations in the ability of tissues to synthesize orotic acidde novoare determined by similar variations in their ability to synthesize carbamoylphosphat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04436.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY