摘要:

Abstract—The activity of cyclic AMP phosphodiesterase of rat cerebral homogenates increased several‐fold between 1 and 60 days of age. Enzyme activity in the cerebellum, on the other hand, did not increase during this period. A kinetic analysis of the phosphodiesterase activity revealed evidence for multiple forms of the enzyme and indicated that the postnatal increase in phosphodiesterase activity of rat cerebrum was due almost exclusively to the high Kmenzyme. In cerebellum, the ratio of the high and lowKmenzyme remained fairly constant during ontogenetic development.Physical separation of the phosphodiesterases contained in 100,000 g soluble supernatant fractions of sonicated brain homogenates by polyacrylamide disc gel electrophoresis confirmed the presence of multiple enzyme forms. In adult rats we found six distinct peaks of phosphodiesterase activity (designated I to VI according to the order in which they were eluted from the column) in cerebellum and 4 forms of the enzyme (Peaks I through IV) in cerebrum. Brains of newborn rats had a different pattern and ratio of phosphodiesterase activities. For example, Peak I phosphodiesterase was undetectable in cerebrum or cerebellum of newborn rats. Moreover, in the cerebellum of newborn rats Peak II was the dominant peak whereas in the cerebellum of adult rats Peak III was the largest peak. A comparison of the multiple forms of phosphodiesterase from the cerebrum of newborn and adult animals suggested that the postnatal increase in phosphodiesterase activity previously seen in crude homogenates was due largely to an increase in a high K, Peak II phosphodiesterase. The ratios of activities of the other peaks and their sensitivities to an activator of phosphodiesterase were similar in newborn and adult rats.An endogenous heat‐stable activator of phosphodiesterase was found in cerebrum, cerebellum and brain stem. In newborn rats, the cerebellum contained several‐fold less activity of this activator than did cerebrum or brain stem. However, the activity of this activator increased with age in the cerebellum and would appear to have decreased postnatally in cerebrum and brain stem.These results suggest that some multiple forms of phosphodiesterase can develop independently and that changes in activities of these phosphodiesterases may occur by increases in the quantity of enzyme or by changes in the quantity of an endogenous activator of phosphodie

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12204.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Apomorphine (A) inhibited dopamine deamination by rat brain mitochondria, but did not influence catechol‐O‐methyltransferase (COMT) activity by brain homogenates. The administration of apomorphine (10mg/kg i.p.) to normal rats increased brain dopamine (DA) by 34 per cent and decreased homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) by 60 per cent. In rats treated with reserpine 15 min prior to A, the latter prevented the rise of cerebral HVA and DOPAC and the depletion of DA produced by the former. Finally, A decreased the L‐DOPA‐induced accumulation of HVA and DOPAC in the rat basal ganglia. These results indicate that A inhibits DA deamination by monoamine oxidase.This inhibition seems to be specific since apomorphine did not influence 5‐HIAA levels in normal rats and prevented neither central 5‐HT depletion nor 5‐HIAA rise induc

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12205.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The ACh content of the rat hippocampus, visual cortex, auditory cortex and corpus striatum was estimated as so‐called free, labile‐bound and stable bound acetylcholine at different times after the learning of a brightness discrimination.In the hippocampal region the free acetylcholine was highly increased immediately after the training, whereas the stable bound ACh and the labile‐bound fraction rose 70 min and 4 h respectively‐after completion of training.Only small alterations of the ACh fractions were observed in the visual and auditory cortices. In the corpus striatum no changes

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12206.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—–Muscle of shrimps (Artemisia longinaris) were extracted with chloroform‐methanol (2:1, v/v) and the proteolipids were separated by column chromatography on Sephadex LH‐20. Three peaks of protein were eluted with chloroform and one with chloroform‐methanol (4:1, v/v). Only the first peak eluted between 16 and 26 ml of chloroform showed binding forl‐(14C]‐glutamate. The type of saturation curve obtained suggests the existence of single type of binding site. The saturation is reached at one mole ofl‐glutamate per 320,000 g protein and the purification achieved about 3200‐fold. The protein binding‐glutamate does not bind GABA, aspartate or glutamine. The binding ofl‐[14C]‐glutamate was inhibited bydl‐α ‐methyl glutamic acid andl‐glutamic acid diethyl ester. The binding properties of this hydrophobic protein fraction suggest that it may represent the isolated glutamate

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12207.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The total lipid extract of shrimp muscle (Artemisia longinaris) was precipitated with ether. The supernatant containing 95 per cent of the phospholipids and 50 per cent of the protein showed binding for L‐[14C]glutamatc in the first peak of protein. The sediment, redissolved in chloroform‐methanol was chromatographed on a Sephadex LH‐20 column. A single peak was eluted in the chloroform (20‐40 ml) having no lipid phosphorous and high affinity binding for [14C]GABA. The saturation was achieved at 1 mole per 80.000 g protein and the curve revealed a single type of binding site. The purification achieved was of about 4000‐fold. There was no binding of L‐[14C]glulamate to the ether precipitate. The specificity of the binding of [14C]GABA was further supported by competition experiments with bicuculline. picro‐toxin and muscimol. It is suggested that the hydrophobic protein isolated by us represents the GABA receptor. The findings presented in the two papers of the series suggest that the excitatory and inhibitory receptor from crustacean muscle can be separated as two dif

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12208.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—A comparative study of the concentration and fatty acid distribution in diacyl‐ and triacylgly‐cerols. free fatty acids and total phospholipids from rabbit, cattle and toad retina is presented. With respect to the toad, a comparison is made with brain, choroid and plasma lipids. Marked differences in diacylglycerol composition and levels between mammalian and toad retina are found: in the mammal arachidonate predominates (25 per cent), in the toad docosahexaenoate is the main fatty acid (42 per cent). The total phospholipid composition parallels that of the diacylglycerols only in the toad, whereas in the mammalian retina the phospholipids are richer in docosahexaenoate than are the diacylglycerols. It is suggested that there is a relationship between diacylglycerols and phosphoglyceride metabolism in the toad; in the retinas of other species the diacylglycerols may be related to specific phosphatides. In the three species, triacylglycerols show high levels of unsaturation; however, marked differences are found in the distribution of polyunsaturated acyl groups: in the cattle and toad retina docosahexaenoate predominates. whereas in the rabbit a higher proportion of 22:4 is found. Retina free fatty acid pools also show different features in the three species: the cattle retina contains the highest proportion of free 20:4 and 22:6. The triacylglycerol concentration is much higher in the toad choroid than in the retina, although the fatty acid compositions are similar. A possible relationship between these choroid lipids and those of the retina is sugg

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12209.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—–A preparative procedure for the isolation in bulk of two cellular populations of the cerebellar cortex of the immature rat, the granule cells and the Purkinje cell bodies, is described. The procedure is used to delineate the developmental pattern of succinate‐INT‐reduclase (EC 1.3.99.1) and acetylcholinesterase (EC 3.1.1.7) in the crucial period of cerebellar maturation, i.e. between 12 and 19 days postnatally. Although the overall yield of neuronal RNA diminished with age, the proportion of RNA in the Purkinje cell body fraction increased while that in the granule cells decreased and microscopic examination of the fractions confirmed this result. The yields of succinate‐INT‐reductase and of acetylcholinesterase in the fractions paralleled the yields of RNA. A significant finding was the trend toward diminishing specific activities (units/μg of RNA) with age of both enzymes in the Purkinje cell bodies as against the opposite, upward trend of their specific activities in the granule cells. An additional finding of interest was the different ratio of true acetylcholinesterase/total cholinesterase activity in the two cell types, with the granule cells consistently exhibiting higher true acetylcholinesterase values than the Purkinje cell bodies. The present report thus supplements the histoenzymological data on the developing rat cerebellum in that it reveals specific differences in the enzymatic development of two different cerebellar types, a finding which was greatly facilitated by the availability of the procedure for their bu

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12210.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Synaptosomes prepared by differential and Ficoll density gradient centrifugation took upd‐galactose by two saturable transport systems: one. a high affinity system with aKmof 0‐25 mn and Vmaxof 075 nmol/mg protein 3 min, the other, a low affinity system with aKmof 47 mM and aVmaxof 135 nmol/mg protein/3 min. The high affinity system was inhibited by 1‐5 mM phlorizin but was unaffected by the absence of sodium ion or the presence of 1 mM ouabain. The low affinity system was unaffected by phlorizin or ouabain. Both systems were inhibited by high concentrations of glucose. 2‐deoxyga‐lactose. and inositol, and by 2.4‐dinitrophcnol. Galactose was rapidly converted in synaptosomes to phos‐phorylatcd intermediates and was more slowly

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12211.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The calcium‐dependent incorporation of choline, ethanolamine and L‐serine into the phospholipids of isolated rat brain microsomes has been studiedin vitro,and various properties of the incorporation have have been examined. The optimum pH for the incorporation of each base was found to vary inversely with the Ca2‐concentration. Conversely, the optimal Ca2 +concentration for the exchange of the bases increased with decreasing pH values. The enzymic system for the incorporation of ethanolamine appeared to be saturated by two substrate concentrations, i.e. 0‐2 and 1‐7‐2‐0 mM. At low ethanolamine concentration (0‐2 mM] much less incorporation of the base occurred into the alkenylacyl‐ and alkylacyl‐derivatives of ethanolamine phosphoglycerides compared to that into the diacyl species, whereas the difference becomes smaller at a high substrate concentration (1‐7 mM). At pH 81 and 2 mM‐Ca2+the apparentKmof ethanolamine at low substrate concentration was 80 × 10‐5M, and this value increased to 16‐2 × 10‐4.viat 10mM‐Ca2+concentration. At similar pH theKmvalues for choline and L‐serine were 5.88 × 10‐4M and 40 × 10‐4M at 2 mM‐ and 10mM‐Ca2 +concentrations, respectively. The properties of the enzyme system show differences for the three substrates when various factors are changed during incubation. These and other results indicate that more than one enzyme is probably involved in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12212.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Several sulphatases (arylsulphatases A, B and C, cholesterol sulphatase, dehydroepiandroster‐one sulphatase, cerebroside sulphatase and psychosine sulphatase) were deficient in various tissues from two patients with a variant form of metachromatic leukodystrophy. Deficient activities of cerebroside sulphatase and psychosine sulphatase, using physiological substrates, in tissues from metachromatic leukodystrophy with multiple sulphatase deficiencies provided another example that these enzymes may be identical to arylsulphatase A. β‐Galactosidase activity was reduced to about 30‐50 per cent of normal in brain and liver. Other lysosomal enzyme activities were found to be normal or elevated five to eight times. Arylsulphatase B isolated from the liver of one patient was abnormal, with respect to pi (70) and enzyme kinetics. In mixing experiments with normal enzymes the reduced activities of arylsulphatases A. B and C, cerebroside sulphatase and steroid sulphatases were shown not to be due to the presence of endogenous inhibitors. No arylsulphatase A or B activity in the brain specimen from the patient with multiple sulphatase deficiencies could be detected on isoelectric focussing. In normal brain tissue arylsulphatase A had a pi of 4‐6‐4‐8 while arylsulphatase B had a pi of 7‐8 and 8‐1. When 4‐methylumbelliferyl sulphate was used as a substrate the elution patterns of normal brain and liver arylsulphatase B were more heterogeneous and showed more variation than that whenp‐nitrocatechol sulphate was used. Arylsulphatase C and steroid sulphatases (cholesterol sulphatase, dehydroepiandrosterone sulphatase and oes‐trone sulphatase I were solubilized by the addition of lysolecithin and Triton X‐100 and subjected to isoelectric focussing. The pi of cholesterol sulphatase, oestrone sulphatase and arylsulphatase C was 6‐8, and the elution patterns of the activities of these enzymes were similar. The pattern of dehydroepiandrosterone sulphatase was more heterogeneous and two major peaks were observed at pi 6 5 and 70. Residual enzyme activities of arylsulphatase C and steroid sulphatases from the brain of the patient with multiple sulphatase activities were not detectable by isoelectric focussing. Simultaneous deficiencies of arylsulphatase C and steroid sulphatases plus isoelectric focussing findings in tissues suggest that these enzymes are closely related in regard to their function. The nature of the genetic defect in metachromatic leukodystrophy with multiple sulphata

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12213.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY