George L. Ellman

A NEW AND RAPID COLORIMETRIC DETERMINATION OF ACETYLCHOLINESTERASE ACTIVITY

Abstract A photometric method for determining acetylcholinesterase activity of tissue extracts, homogenates, cell suspensions, etc., has been described. The enzyme activity is measured by following the increase of yellow color produced from thiocholine when it reacts with dithiobisnitrobenzoate ion. It is based on coupling of these reactions: The latter reaction is rapid and the assay is sensitive (i.e. a 10 μ1 sample of blood is adequate). The use of a recorder has been most helpful, but is not essential. The method has been used to study the enzyme in human erythrocytes and homogenates of rat brain, kidney, lungs, liver and muscle tissue. Kinetic constants determined by this system for erythrocyte eholinesterase are presented. The data obtained with acetylthiocholine as substrate are similar to those with acetylcholine.

TRITON SOLUBILIZED ACETYLCHOLINESTERASE OF BRAIN

—The total AChE of brain can be readily extracted into aqueous Triton X‐100. By column chromatography of these extracts a preparation was obtained at least six times as active as the original material and in yields of 60‐80 per cent of the original amounts. The molecular weight of this material was estimated to be over 200,000. When brain tissue was treated with venom or bacterial protease, a water‐soluble AChE was obtained with an overall purification of 150‐fold. The most active preparation of AChE hydrolysed 880 μ‐moles of acetylthiocholine/hr/mg of protein. The molecular weight of this preparation was estimated to be about 100,000. The enzyme which was extracted by Triton X‐100 is probably the precursor of the more water‐soluble enzyme that can be prepared from brain tissue by treatment with venom or protease.

Alcohol, habituation and the patterning of aggressive responses in a cichlid fish ☆

Territorial cichlids were presented for 30 min with a conspecific male intruder (contained in a clear glass tube). Eight hr prior, 2 groups were administered alcohol (0.15 or 0.30 percent in the aquaria water). A third group served as a control. Three responses were recorded to allow analysis of topographic changes in behavior as well as changes in absolute levels. During the habituation phase, the normal group showed a sequence of long displays, followed by shorter ones as the frequency of attacks increased. The occurrence of threat which gradually gives way to attack is characteristic of the agonistic behavior of this species. In contrast to the controls, the 0.15 percent group was hyperaggressive, while the 0.30 percent group was hypoaggressive. Furthermore, the patterning of responses were abnormal. The 0.15 percent group gave abbreviated threats and more attacks (interpreted as a tendency to attack without warning); whereas, the 0.30 percent group gave many long threat displays, but few attacks. A stimulus specificity test provided strong evidence that the waning found during the initial phase was habituation.

Responses of the cells of the supra-optic nucleus; Kinetic aspects

SummaryRats of two strains were provided with 2.5% salt water to drink instead of tap water. This stress to the adrenal-hypophysis system results in a series of changes in the cells of the supra-optic nucleus; the progress of these changes was studied. The enlargement of the cells occurs at a very early stage, whereas the development of rough endoplasmic reticulum occurs somewhat later. These changes are discussed in terms of a model of neuron reactivity to firing.

Cortisol and Behaviorally Conditioned Histamine Release

During the experiments on conditioning of blood histamine levels in the guinea pig which preceded the studies reported by Dark, Peeke, Ellman and Salfi,4 we noticed that the animals that seemed most agitated could be conditioned better than the calmer ones. We had no hard data to substantiate the impression. The prior stress conditioned experiment described by Dark et aL4 was a successful attempt to experimentally manipulate the stress variable. The group that was mildly stressed prior to conditioning conditioned much better than the unstressed group. In addition to the assays for plasma histamine, we also assayed part of each sample for corticoid levels. The methods are described in more detail in Dark et al.4 In brief, guinea pigs were sensitized with bovine serum albumin (BSA), and then 3 weeks later they were classically conditioned using a discrimination conditioning procedure where one neutral odor was paired with BSA and another was not paired. Hence all animals received one odor paired with an allergen and another that was not. After ten weekly trials, five with odor plus allergen and five with a different odor not paired, three extinction trials were administered, one each week. The first and third extinction trials presented the odor previously paired with the allergen, but not presented alone. The second trial was the neutral odor always unpaired with allergen. The results showed that there was no differences between animals that were conditioned and those that were not with respect to cortisol levels before sensitization or during and after handling, even though handling was clearly stressful as judged by behavioral data collected during handling.

Lithium ion and water balance in rats

Abstract Rats were required to drink 15–50 m m lithium chloride instead of water. Profound depletion of the neurosecretory material in the hypophysis and swelling of the cells of the supra-optic nucleus were observed. Serum concentration of lithium ion was 0.3–0.4 m m . These effects were qualitatively similar to those seen on ingestion of 430 m m NaCl; however, an opposite effect on drinking behavior was observed. These changes are interpreted in terms of interference with the normal functions of vasopressin.

Effects of alcohol congeners and acetaldehyde on aggressive behavior of the convict cichlid

Ethanol and three beverage alcohols were examined for their effects on the aggressive responses of the convict cichlid. At an ethanol concentration that gave negligible effects on the basal level of these responses, rum was observed to depress aggression. As its concentration of acetaldehyde was significantly higher than that of the other beverage alcohols, we assessed the effects of acetyldehyde on the aggressive responses, as well as the locomotor activity of the fish. At 4mg/l, acetaldehyde completely inhibited aggressive responses, without affecting locomotor activity. It is likely, however, that acetaldehyde does not explain the entire inhibitory effect of rum on the aggressive responses of the cichlid.

BINDING OF 5-HYDROXYTRYPTAMINE TO ACIDIC LIPIDS IN AN AQUEOUS MEDIUM

The affinities of 5‐hydroxy‐[3H]tryptamine (5‐HT) for cerebroside sulfate, 1‐phosphatidylinositol, 1‐phosphatidylinositol 4‐phosphate, 1‐phosphatidylinositol 4,5‐bisphosphate, phosphatidic acid, and phosphatidyl serine were determined in an aqueous medium. They were observed to be, in general, much lower than and poorly correlated with the values previously reported by Johnsonet al (1977a), measured in isobutanol. This suggested that these lipids probably are not 5‐HT receptors and that drug affinities measured in organic media must be evaluated with caution.

Sulfhydryl Groups in Nissl Bodies

SummaryStructures which contain the major part of the insoluble cytoplasmic sulfhydryl material have been identified with the protein components of the Nissl bodies of neurons. This was done by showing with histochemical techniques the topographical coincidence of reactive sulfhydryl cell regions, and areas selectively stained for nucleic acids. This identification is of considerable interest with respect to nervous tissue, as it was possible to show that the staining for sulfhydryl and nucleic acids in Nissl bodies was increased or decreased as the cells were stimulated or undergoing chromatolysis.

Lifetime antipsychotic-drug exposure, dyskinesia and related movement disorders in the developmentally disabled

The relationship between dyskinesia and related movement disorders was examined as a function of cumulative exposure to antipsychotic drugs (APD). Lifetime drug-exposure histories were obtained for 162 developmentally disabled (DD) persons; drug-exposed groups were compared to nondrug-exposed groups. There were no statistically significant relationships between dyskinesia and the amount of lifetime APD exposure, nor between dyskinesia and the number of long-term APDs, mean exposure, peak exposure, recency of exposure, duration of exposure, changes in medication levels, number of drug interruptions, age, gender, cerebral palsy, epilepsy, or IQ. Of the other movement disorders, a positive relationship was noted only between akathisia and long-term APD exposure; the increased prevalence of akathisia persisted beyond four years after APD withdrawal.