摘要:

Abstract:Cyclic AMP content was determined in 12 brain regions of young adult female mice at 30 min and at 24 h following an intraperitoneal injection of the tri‐substituted adrenocorticotropic hormone(4–9) [ACTH(4–9)] analogue Organon 2766 [ORG 2766]. Animals were killed by focused 3.5 kW microwave radiation applied for 350 ms. Unlike previously reported responses in male mice, at 30 min post‐injection there were no detectable differences in cyclic AMP content between the placebo and ORG 2766‐treated animals. By contrast, 24 h after injection, the content of cyclic AMP was changed significantly in 8 of the 12 brain regions examined: medulla‐pons, septal area, thalamus, hypothalamus, hippocampus, olfactory bulb, and parietal and occipital cortices. In most of the regions examined, differences consisted of 50% or greater reductions of tissue cyclic AMP content. The changes were unrelated to the estrus cycle of t

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12520.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The Egyptian fruit batRousettus aegyptiacusdevelops severe vitamin B12deficiency when fed a diet of fresh peeled fruit and water. In a group of bats fed this diet, B12concentrations in the serum and brain were low, and neurological impairment, evidenced by deficient or absent hindlimb groping or grasping ability and climbing difficulties, was manifest. Control bats fed the identical diet supplemented with B12showed no such changes. Fatty acid analysis of whole brain homogenates showed a higher level of 20:4 in the deficient group. Phosphatidylcholine showed a marginally higher percentage of 18:3. The total percentage of branched chain fatty acids of phos‐phatidylethanolamine was four times higher in deficient brains, comprising 2% of the total. Sphingomyelin showed a slightly higher percentage of 15:0, and a significantly lower percentage of long chain fatty acids C‐24 and longer (p<0.01). The compositions of nonhydroxy fatty acids in cerebroside were unchanged. Examination of phospholipids showed that 8.9 ± 0.4% of total phosphorus was present as sphingomyelin in deficient bats, compared with 11.9 ± 1.2% in control animals (p<0.05). There were no statistically significant differences in the concentrations of total brain lipid, protein, phospholipid, glycosphingolipid, cholesterol and plasmalogen between B12‐deficient and contr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12521.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The PO protein of the myelin of chick sciatic nerve was isolated and purified by propanoic acid extraction of peripheral nervous system (PNS) myelin, delipidation, Sepharose CL‐6B chromatography in the presence of sodium dodecyl sulfate (SDS), and preparative SDS‐polyacrylamide gel electro‐phoresis (PAGE). Approximately 15% of the PO protein in the sciatic nerve myelin was recovered in a homogeneous state. The purified protein monomer has an apparent molecular weight of 32.1K as determined by gel electrophoresis. The PO protein undergoes extensive aggregation during exhaustive dialysis and freeze‐drying and yields stable dimers, trimers, and tetramers. The aggregation of the PO protein after freeze‐drying is independent of the presence of a reducing agent (2‐mercaptoethanol) in the solubilizing medium. The PO protein is a glycoprotein. The amino acid composition of the chick PO protein indicates a definite species difference when compared with mammalian PO proteins although the NH2‐terminal isoleucine residue seems to have been retained dur

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12522.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Adenylate cyclase was solubilized from washed paniculate fraction of rabbit cerebral cortex with the nonionic detergent Lubrol 12A9 and subjected to either gel filtration on Ultrogel AcA 34 or chromatography on DEAE Bio‐Gel A. By both procedures the enzyme was resolved into two components, one insensitive to guanyl 5′‐yl imidodiphosphate [Gpp(NH)p] and NaF but stimulated by Ca2+and calmodulin, and another that was sensitive to Gpp(NH)p and NaF but relatively insensitive to Ca2+and calmodulin. The data support the possibility that two independent forms of adenylate cyclase exist in cerebral cortex, one regulated by guanine nucleotide regulatory protein and another by Ca2+‐calmodulin. Fractions containing the guanylnucleotide‐sensitive activity were found to contain a factor that inhibited basal and Ca2+‐stimulated adenylate cyclase in the Ca2+‐sensitive fraction. The inhibitor was inactivated by heating at 60°C and by incubation with trypsin. Inhibition was not time‐dependent, and it was not due to destruction of cAMP by phosphodiesterase or of ATP by ATPase. Inhibitory action was not reversed by calmodulin and therefore it does not appear to be a calmodulin binding protein. Sucrose density gradient sedimentation indicated a sedimentation coefficient of 4S for the inhibitor; by this technique it co‐sedimented with the adenylate cyclase sensitive t

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12523.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The catecholamine secretory function of a preparation of isolated bovine adrenal chromaffin cells has been further characterized under conditions designed to elucidate the mechanism of calcium channel activation and the possible role of cytoskeletal elements in stimulus‐secretion coupling. Three related sets of data were obtained: (1) Differences in kinetics, Ca dependence, strength, and additivity of the secretory response to acetylcholine (ACh) versus excess K; (2) the effects on secretion of the Ca channel‐blocking agents, Ni, Mg, and verapamil; and (3) the Ca dependence of vinblastine action on ACh‐ and K‐evoked secretion. The results suggest that a major portion of the Ca influx required for catecholamine release enters the cell via voltage‐dependent Ca channels with some additional Ca influx via the ACh receptor channel. Comparison of the present secretion data with corresponding known electrophysiological properties of isolated chromaffin cells provides added evidence for a role of chromaffin cell action potentials in regulation of Ca influx and the secretory response. Elevated Ca concentrations enhanced K‐evoked secretion to levels comparable to that of ACh but did not induce a vinblastine block of K‐evoked release. This provides further evidence against a role of microtubules in the common exocytosis event per se. However, a role of cytoskeletal elements in directing the movement of secretory granules, or an action of vinblastine at cholinergic receptors, remain distinct

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12524.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Evidence based on the ability to accumulate [3H]noradrenaline by a mechanism sensitive to desmethylimipramine suggests that there is a period of hyperinnervation of the cerebellum by noradrenergic fibres around the beginning of the second postnatal week. Different developmental profiles for specific noradrenaline uptake and noradrenaline content indicate that invasion of the tissue by noradrenergic fibres precedes their full acquisition of transmitter. Developmental increases in the density of β‐receptors and adenyl cyclase responsiveness to isoproterenol lags behind those of the presynaptic components and does not begin until the hyperinnervation is declining around day

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12525.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:When rat brain mitochondria are incubated with [γ‐32P]ATP, there is a rapid (10 s) phosphorylation of proteins designated E, and F of M.W. 42,000 and 32,000, respectively. Although [γ‐32P]ATP was the preferred substrate for protein F, a small amount of labeling did occur with [γ‐32P]GTP. Phosphorylation of E1was absolutely ATP‐dependent. On the other hand, a 32,000 M.W. protein from rat liver mitoplasts (mitochondria devoid of an outer membrane) was highly phosphorylated when [γ‐32P]GTP was used but not at all phosphorylated within short time periods with [γ‐32P]ATP. Both the ATP‐labeled brain phosphoprotein F and GTP‐labeled liver protein migrated to identical positions on high‐resolution two‐dimensional polyacrylamide gels, and both contained acid‐labile phosphoryl groups. Furthermore, both phosphoproteins were identified as the autophosphorylated subunit of succinyl‐CoA synthetase (SCS, EC 6.2.1.4) by using antibody directed against purified GTP‐dependent porcine SCS. However, immunotitration experiments with anti‐porcine SCS revealed that ATP‐ and GTP‐labeled protein F in brain differed in their interactions with antibody, suggesting that in rat brain mitochondria two different forms of the enzyme exist that are immunologically distinct and differ in substrate specificity. When mitochondrial preparations enriched in particular brain cell or subcellular types were examined, an unequal distribution of E1and the two forms of protein F were observed. A brain subfraction containing neuronal cell body and glial mitochondria (CM) was found to contain E1and approximately equal amounts of the ATP‐ and GTP‐dependent forms of protein F. Light synaptic mitochondria(SM1) contained ATP‐dependent protein F almost exclusively and were depleted in E1. Dense synaptic mitochondria (SM2) are rich in the ATP form of SCS but

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12526.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:In the present study, the properties, such as pH optima, detergent requirement, and effects of various lipids, of cholesterol ester hydrolase in human cerebrospinal fluid (CSF) were examined, and the activity levels of the enzyme in CSF from multiple sclerosis (MS) patients and non‐MS individuals were compared. Our data indicate that the enzyme in CSF exhibits two pH optima: pH 6.0 in the presence of Triton X‐100 and pH 7.0 in the presence of sodium taurocholate. Both phosphatidylethanolamine (PE) and phosphatidylserine (PS) enhanced the hydrolase activity at pH 6.0. The activity at pH 7.0, on the other hand, was enhanced slightly in the presence of PE but was inhibited in the presence of PS. These data suggest the presence of two cholesterol ester hydrolases in CSF and also indicate that the activity at pH 6.0 may be due to microsomal enzyme in brain and that at pH 7.0 may be due to myelin enzyme. The hydrolase activity at pH 7.0 was significantly lower in CSF from MS patients. The activity at pH 6.0 in CSF from MS and non‐MS patients, however, did not differ significantly. This indicates that the reduction in pH 7.0 hydrolase activity in CSF may be related to demyelin

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12527.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Treatment of PC 12 pheochromocytoma cells with nerve growth factor (NGF) resulted in increased levels of neuron‐specific enolase (NSE). Neither insulin, growth hormone, cytochromec, nor sodium butyrate increased NSE levels. Epidermal growth factor (EGF) did increase NSE levels, although not to the same extent as NGF. As little as 1 ng/ml NGF induced the maximal increase in NSE. As PC 12 cells increased in density, the NSE levels increased even in untreated cell

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12528.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Time courses of the activation‐inactivation sequence in rat midbrain tryptophan hydroxylase after preincubation with calcium, ATP + MgCl2, or sulfhydryl reagents and after freezing and thawing suggest that the activated enzyme is more vulnerable to loss of activity. The sequence induced by calcium was prevented by the protease inhibitor leupeptin, and an accelerated decline in activity after activation by ATP + MgCl2was reduced greatly by increasing levels of tetrahydrobiopterin (BH4) cofactor. The effects of calcium and ATP + MgCl2were additive, which suggests independent mechanisms. The findings suggest that time courses of enzyme activation and inactivation processes may offer a useful way to study the influence of a range of effectors on tryptophan hydroxylase functio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12529.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY