Binding sites with high affinity and specificity for [3H]quinuclidinyl benzilate (QNB) are present in homogenates of rat brain. The characteristics of the binding sites resemble those of muscarinic cholinergic receptors. Specific binding is saturable with respect to [3H]QNB and tissue concentration and is time-, temperature-, and pH-dependent. The bimolecular rate of association (2.0 × 108 M-1 min-1) and dissociation (1.2 × 10-2 min-1) at 35° indicate a dissociation constant of 60 pM and a density of 65 pmol/g of brain. Muscarinic antagonists and agonists displace specific [3H]QNB binding, while nicotinic and non-cholinergic drugs possess little affinity for [3H]QNB-binding sites.

https://www.pnas.org/content/pnas/71/5/1725.full.pdf

Muscarinic Cholinergic Binding in Rat Brain

1. The methods for the assay of choline acetyltransferase were based on the reaction between labelled acetyl-CoA and unlabelled choline to give labelled acetylcholine. 2. Both synthetic acetyl-CoA and acetyl-CoA formed from sodium [1-(14)C]acetate or sodium [(3)H]acetate by incubation with CoA, ATP, Mg(2+) and extract from acetone-dried pigeon liver were used. 3. [1-(14)C]Acetylcholine was isolated by extraction with ketonic sodium tetraphenylboron. 4. [(3)H]Acetylcholine was precipitated with sodium tetraphenylboron to remove a ketone-soluble contaminant in sodium [(3)H]acetate and then extracted with ketonic sodium tetraphenylboron. 5. The values of choline acetyltransferase activity obtained in the presence of sodium cyanide or EDTA and synthetic acetyl-CoA were similar to those obtained with acetyl-CoA synthesized in situ. 6. The assay of acetylcholinesterase was based on the formation of labelled acetate from labelled acetylcholine. The labelled acetylcholine could be quantitatively removed from the acetate by extraction with ketonic sodium tetraphenylboron. 7. The methods were tested with samples from central and peripheral nervous tissues and purified enzymes. 8. The blank values for choline acetyltransferase and acetylcholinesterase corresponded to the activities in 20ng. and 5ng. of brain tissue respectively.

Radiochemical micro assays for the determination of choline acetyltransferase and acetylcholinesterase activities.

A rapid microfluorimetric determination of monoamine oxidase

Subcellular Distribution of Adenyl Cyclase and Cyclic Phosphodiesterase in Rat Brain Cortex

Brain cholinergic dysfunction and memory in aged rats

PREVIOUS studies have indicated that levels of activities of 5-hydroxytryptophan decarboxylase (5-HTPD) and monoamine oxidase (MAO) may have a significant role in regulating tissue concentrations of 5-HT. Investigations of such enzyme activities in brain tissue have been performed on relatively gross areas (100 mg or more) which contain varying amounts of grey and white matter. For better assessment of the contribution of each of various cell types, microdissection of cortical and cerebellar areas was performed. Since the sample size of a relatively homogeneous cellular population is of the order of a few pg, new, sensitive micromethods had to be devised for the measurement of M A 0 and 5-HTPD activities. Methods currently used for the quantitative estimation of M A 0 activity by oxygen consumption, ammonia production, disappearance of amine, and fluorimetric assay of indole acetic acid formed are not sufficiently sensitive for such studies. The method frequently used for estimating the activity of the enzyme which decarboxylates 5-HTP and dihydroxyphenylalanine, is based on the fluorimetric estimation of the products 5-HT and dopamine, respectively. KUNTZMAN, SHORE, BOGDANSKI and BRODIE (1961) recently described modifications of these methods which increase their sensitivity, but, even with modifications, approximately 20-100 mg of brain tissue are required. In this paper, procedures are described for quantitative estimation of M A 0 and 5-HTPD activities in samples of nervous tissue weighing as little as 2-5 pg dry weight. Certain properties of the enzymes in various tissue homogenates, as well as distribution of activities within discrete areas of the nervous system, are presented. Preliminary descriptions of these methods have been previously reported (MCCAMAN, R. E., 1961 ; MCCAMAN, 1962). METHODS All the reagents used were analytical grade. Preparations of 14C-labelled 5-HT, 3-hydroxytyramine and tyramine with different specific activities were obtained from various commercial sources, and all tested gave equivalent answers in the described procedures. The DL-[~-'*C]~-HTP was obtained from New England Nuclear Corporation. This material is now available from ChemTrac Corporation, Boston, Massachusetts. The general techniques for handling small amounts of tissue and the appropriate volumes have been previously described (LOWRY, 1953 ; LOWRY, ROBERTS, LEINER, WU and FARR, 1954). The buffer substrate solution (0.1 M-potassium phosphate, pH 7.2; 0.8 m~-[3-'~C]serotonin) was stored at -20\" until needed. Ten pl of ice-cold buffer substrate were added to the sample, which was equivalent to 1-20 pg dry brain or 1 pl of homogenate (1 g tissue per 25 ml H,O), in a pointed microtube of 2.5 mm I.D. x 4 cm. The tube was placed in a tray of M A 0 determination.

Microdetermination of monoamine oxidase and 5-hydroxytryptophan decarboxylase activities in nervous tissues.

THIS study was initiated to develop a simple and sensitive procedure for the determination of choline acetylase (ChAc) activity in microgram or submicrogram samples of nervous tissue. Currently available methods require milligram quantities of nervous tissue and can not be utilized even with severe modification. This communication describes in detail a method which has been successfully applied to samples of rabbit nervous tissue weighing as little as 0.4 pg dry weight. A preliminary report of this study has been published (MCCAMAN, 1963).

Microdetermination of choline acetylase in nervous tissue.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

J. M. Hunt

Author Tools

Chat about Author

Papers

Microdetermination of monoamine oxidase and 5-hydroxytryptophan decarboxylase activities in nervous tissues.

Microdetermination of choline acetylase in nervous tissue.