摘要:

Abstract:The long‐term regulation of tyrosine hydroxylase (TH) by serotonin has been studied with cultures of newborn rat locus ceruleus explants. The presence of serotonin in the culture medium for a 24‐h period was followed by an inhibition of TH activity in the explants. This effect lasted several days, with a maximal effect 2 days after treatment. Moreover, the decrease was reversible and dependent on the concentration of serotonin used (from 1 μMto 1mM).The mechanisms of this regulation have been studied using drugs such as those known to act specifically on serotoninergic receptors and those known to interfere with protein synthesis. Thus, the action of serotonin (10−5M)on TH activity was suppressed with equimolar concentrations of serotoninergic antagonists such as metergoline or methiothepin.It was reproduced by quipazine, a drug capable of acting as a serotoninergic agonist. Inhibitors of protein synthesis acting either at the transcriptional or the translational levels can reproduce the inhibition ofTHactivity by serotonin alone. Furthermore, the effects of one or the other of these compounds and that of serotonin were not additive. This study confirms the hypothesis of an inhibitory control by serotonin on TH activity in the noradrenergic neurons of the locus ceruleus. Serotonin could regulate the synthesis of the enzyme through specific serotoninergic rec

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Metorphamide is a [Met]‐enkephalin‐containing opioid octapeptide with a C‐terminal α‐amide group. It is derived from proenkephalin and is, so far, the only endogenous opioid peptide with a particularly high affinity for μ opioid (morphine) receptors, a somewhat lesser affinity forKopioid receptors, and a relatively low affinity for δ opioid receptors. The concentrations of metorphamide in the bovine caudate nucleus, the hypothalamus, the spinal cord, and the neurointermediate pituitary were determined by radioimmunoassay and chromatography separation procedures. Metorphamide concentrations were compared withthe concentrations of eight other opioid peptides from proenkephalin and prodynorphin in identical extracts. The other opioid peptides were [Met]‐enkephaIyl‐Arg6‐Phe7and [Met]‐enkephalyl‐Arg6‐Gly7‐Leu8from proenkephalin; α‐ neoendorphin, β‐neoendorphin, dynorphin A(l‐8), dynorphin A(1–17), and dynorphin B from prodynorphin; and [Leu]‐enkephalin, which can be derived from either precursor. All opioid peptides were present in all four bovine neural tissues investigated. Metorphamide concentrations were lower than the concentrations of the other proenkephalinderived opioid peptides. They were, however, similar to the concentrations of the prodynorphin‐derived opioid peptides in the same tissues. Marked differences in the relative ratios of the opioids derived from prodynorphin across brain regions were observed, a finding suggesting differential posttranslational processing. Differences in the ratios of the proenkephalin‐derived opioids across brain regions were less pronounced. The results from this study together with previous findings on metorphamide's μ opioid receptor binding and bioactivities suggest that the amounts of metorphamide in the bovine brain are sufficient to make this peptide a candidate for a physiologically signif

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:The adenosine A1receptors of sheep brain membranes have been identified by the specific binding of radio‐labeled cyclohexyl [3H]adenosine ([3H]CHA). Pretreatment of membranes with periodate‐oxidized CHA causes a doseand time‐dependent decrease in the number of binding sites. No decrease occurs when membranes are pretreated with CHA. Binding of [3H]CHA to the remaining sites occurs with the same characteristics as binding to the untreated receptor popul

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00947.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Autopsy material from deceased individuals between ages 2 and 90 was used to prepare cerebellum, pons, and other selected regions of the brain, the spinal cord, and peripheral nerves. The concentration of dolichol in these different tissues varied greatly and the increase in concentration during the life span varied between 2.5‐ and 21‐fold. In contrast, dolichyl‐phosphate (dolichyl‐P) was more evenly distributed in these tissues and its concentration increased to a moderate extent only during childhood. The level of cholesterol displayed smaller regional differences and decreased about 15% between ages 35 and 90. Differences in the total phospholipid content were limited. These results demonstrate enrichment and individual regulation of various lipids in specialized regions of the human brain. The independent regulation of dolichol and dolichyl‐P levels in the brain and the possible role of dolichol in the function of the aging nerve cell are also e

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Brain tissue was obtained at autopsy from nine cirrhotic patients dying in hepatic coma and from an equal number of controls, free from neurological, psychiatric, or hepatic diseases, matched for age and time interval from death to freezing of dissected brain samples. Glutamine, glutamate, aspartame, and γ‐aminobutyric acid (GABA) levels were measured in homogenates of cerebral cortex (prefrontal and frontal), caudate nuclei, hypothalamus, cerebellum (cortex and vermis), and medulla oblongata as theirO‐phthalaldehyde derivatives by HPLC using fluorescence detection. Glutamine concentrations were found to be elevated two‐ to fourfold in all brain structures, the largest increases being observed in prefrontal cortex and medulla oblongata. Glutamate levels were selectively decreased in prefrontal cortex (by 20%), caudate nuclei (by 27%), and cerebellar vermis (by 17%) from cirrhotic patients. On the other hand, GABA content of autopsied brain tissue from these patients was found to be within normal limits in all brain structures. It is suggested that such region‐selective reductions of glutamate may reflect loss of the amino acid from the releasable (neurotransmitter) pool. These findings may be of significance in the pathogenesis of hepatic encephalopathy resulting from chronic liver disease. Key Words: Hepatic encephalopathy—Hyperammonemia— Cerebral amino acids—Glutamine—Glutamate—γ‐Aminobutyric acid. Lavoie J. et al. Amino acid changes in autopsied brain tissue from cirrhotic patients with h

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00949.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Axoplasmic RNA from the giant axon of the squid(Loligo pealii)comprises polyadenylated [poly (A)+] RNA, as judged, in part, by hybridization to [3H]polyuridine and by in situ hybridization analyses using the same probe. The polyadenylate content of axoplasm (0.24 ng/μg of total RNA) suggests that the poly(A)+RNA population makes up ∼0.4% of total axoplasmic RNA. Axoplasmic poly(A)+RNA can serve as a template for the synthesis of cDNA using a reverse transcriptase and oligo(deoxythymidine) as primer. The size of the cDNA synthesized is heterogeneous, with most fragments<450 nucleotides. The hybridization of axoplasmic cDNA to its template RNA reveals two major kinetic classes: a rapidly hybridizing component (abundant sequences) and a slower‐reacting component (moderately abundant and rare sequences). The latter component accounts for ∼56% of the total cDNA mass. The rapidly and slowly hybridizing kinetic components have a sequence complexity of ∼2.7 kilobases and 3.1 × 102kilobases, respectively. The diversity of the abundant and rare RNA classes is sufficient to code for one to two and 205, respectively, different poly(A)+RNAs averaging 1,500 nucleotides in length. Overall, the sequence complexity of axoplasmic poly(A)+RNA represents ∼0.4% that of poly(A)+mRNA of the optic lobe, a complex neural tissue used as a standard. Taken together, these findings indicate that the squid giant axon contains a heterogeneous population of p

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00950.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:A neurotrophic factor that promotes the survival of cholinergic parasympathetic ciliary neurons has been purified ∼20,000‐fold from bovine cardiac tissue under nondenaturing conditions using heparin‐affinity chromatography. Up to 22 μg of purified factor having a specific activity of 4 × 105trophic units/mg can be obtained from 250 g of heart muscle. Sodium dodecyl sulfate (SDS)‐polyacrylamide gels of the purified material show a broad band that is sometimes resolvable into a closely spaced pair of bands of 22 and 23 kilodaltons. Partially purified factor can be resolved into two peaks of activity (pI 5.6 and 5.0) by highresolution anion‐exchange chromatography and chromato focusing, although these procedures have not proved useful as purification methods because of the large losses of activity incurred. It is likely that these two peaks represent the two bands seen on SDS‐polyacrylamide gels. The bovine cardiac factor(s) differs from similar factors purified from chick optic tissues and pig brain in that it is irreversibly den

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00951.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:The influence on microtubule assembly in vitro of monoclonal antibodies against microtubule‐associated proteins (MAPs) was studied. Light scattering was used for measuring net polymer formation and electron microscopy for determining the influence of antibodies on microtubule morphology. Control experiments showed that nonimmune mouse IgG had no effect on either the assembly or appearance of microtubules. The same was true for monoclonal antibodies against MAPI. At low levels, antibodies against MAP2 caused the aggregation of microtubules into bundles, an effect that did not occur with antibodies against any other MAP type studied. At increasing concentrations, anti‐MAP2 progressively inhibited tubulin polymerization, producing irregular, shortened filaments. Anti‐MAP5 produced a striking fragmentation of microtubules into very short pieces that were otherwise morphologically identical to control microtubules. The different effects of these antibodies show the potential of monoclonal antibodies for investigating MAP function and form an important adjunct to cellular microinjection experi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00952.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Affinity chromatography has been used for rapid and high‐yield purification of synenkephalin (proenkephalin 1 ‐70) containing peptides present in bovine adrenal medulla (BAM) chromaffin granular lysate. A column of CN‐Br‐activated Sepharose 4B coupled to synenkephalin antiserum bound synenkephalin immunoreactivity which was eluted by a stepwise gradient of 50mMammonium acetate containing 20% (vol/vol) acetonitrile over the pH range 7–3. Synenkephalin immunoreactivity emerged as two peaks, eluting at pH 5.5 and 4.5. Characterization of the two peaks by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and immunoblotting indicated that the pH 5.5 peak contained principally low‐molecular‐weight proenkephalin species (8.6 and 12.6 kilodaltons), whereas the pH 4.5 peak contained, in addition, high‐molecular‐weight proenkephalin species (18.2 and 23.3 kilodaltons). The 8.6‐ and 12.6‐ kilodalton species were isolated from the pH 5.5 peak by TSK gel filtration HPLC, whereas the pH 4.5 peak was further purified by passage over successive affinity columns coupled to antiserum against BAM 22P (proenkephalin 182–203) and [Met5]‐enkephalin‐Arg6‐Gly7‐Leu8. The former column retains the 23.3‐kilodalton species, whereas the latter column retains the 18.2‐kilodalton species. The 23.3‐ kilodalton peptide represents a novel putative proenkephalin intermediate (proenkephalin‐1–206), cont

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00953.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Local cerebral glucose metabolism (LCMRglc) and local cerebral blood flow (LCBF) were studied following implantation of a microdialysis fiber in rat dorsal hippocampus. Recovery time after implantation varied from 0 to 24 h. All rats showed pronounced disturbances in LCMRglc and LCBF during the first 2 h of implantation. The changes consisted of (a) a general decrease in blood flow and glucose phosphorylation and (b) small areas (spots) around the fiber with increased glucose phosphorylation and decreased blood flow. Animals allowed to recover for 24 h demonstrated a near normalization of LCMRglu and LCBF, and the focal disturbances (spots) of glucose phosphorylation and blood flow disappeared. The slight reduction in blood flow and glucose metabolism at this time must be accepted, because extension of the recovery period beyond 24 h may give interpretation problems due to the developing gliosis.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb00954.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY