Norman Weiner

THE DISTRIBUTION OF MONOAMINE OXIDASE AND SUCCINIC OXIDASE IN BRAIN

MONOAMINE oxidase is a widely distributed enzyme which oxidatively deaminates a variety of aliphatic amines (BLASCHKO, 1952). It was first described in rat liver by HARE (1928) and was found to exist in the central nervous system by PUGH and QUASTEL (1937). It was indirectly implicated in central nervous system function by MANN and QUASTEL (1940) when they observed the inhibitory effect of amphetamine on this system. BIRKHAUSER (1941) studied the distributions of monoamine oxidase and cholinesterase in a few parts of the human brain. H e found monoamine oxidase activity was highest in the thalamic and globus pallidus regions, slightly lower in the caudate nucleus and putamen, and lowest in the cortex. The variation in activity from the regions of highest to lowest activity extended only over a two-fold range. Cholinesterase activity was most concentrated in the candate nucleus and putamen, and considerably less concentrated in the thalamus and cortzx. Here the variation was much greater, extending over a 35-fold range. In a more extensive study on dogs BOGDANSKI et al. (1957) found inonoamine oxidase to be somewhat more active in the hypothalamic region, with little differences in activity in most other regions of the brain. Monoamine oxidase is a particulate enzyme, believed to be localized in rnitochondria (COTZIAS and DOLE, 195 1). Succinic dehydrogenase and cytochrome oxidase are also well known mitochondria1 enzymes, though their localization in brain is quite dissimilar from that of monoamine oxidase. These enzymes, according to BURGEN and CHIPMAN (1951) and t o more recent histochemical studies by SHIMIZU and MORIKAWA (l957), predominate in the cellular areas of brain, especially the cerebral and cerebellar cortices. Because of the discrepant distribution of these mitochondrial enzymes it seemed worthwhile simultaneously to examine their distribution in different parts of the brain, both in whole homogenates and in mitochondria1 preparations obtained by differential centrifugation.

A STUDY OF CATECHOLAMINE NUCLEOTIDE COMPLEXES BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY.

SummaryThe direct chemical interaction of catecholamines with adenine nucleotides has been examined using the technique of nuclear magnetic resonance spectroscopy. Preferential stabilization of the alpha and beta carbons of the side chain of epinephrine has been demonstrated by selective changes in the relaxation times of the protons attached to these carbons. By varying the concentrations of amine and nucleotide, it has been shown that at pH 5.6, three molecules of epinephrine can interact with one molecule of ATP and one molecule of epinephrine can interact with one molecule of AMP. An additional catecholamine molecule may be attached to the adenine nucleotide complexes at a higher pH. The complex appears to involve an ionic bond between the catecholamine nitrogen and the phosphate moiety of the nucleotide and a hydrogen bond between the beta hydroxyl group of the catecholamine and a phosphate oxygen. The very small preferential stabilization of the side chain carbons of dopamine in the presence of ATP indicates that the beta hydroxyl group of the catecholamine plays a role in the interaction.

Substrate specificity of brain amine oxidase of several mammals.

Abstract The substrate specificity of brain monoamine oxidase of rat, mouse, dog, cat, rabbit, guinea pig, and human has been determined. The substrate specificity patterns are similar for rat, mouse, dog, cat, and human. Tyramine and dopamine are most readily oxidized. Isoamylamine is a slightly poorer substrate, and epinephrine, norepinephrine, tryptamine, 5-hydroxytryptamine and phenylethanolamine are only moderately readily oxidized. n -Amylamine and phenylethylamine are poor substrates for these five species. Rat and mouse brain in general oxidatively deaminate these amines most rapidly. Human and cat brain contain a considerably less active amine oxidase. Rabbit brain amine oxidase differs from the amine oxidase of rat, mouse, dog, cat, and human in being considerably better able to oxidize n -amylamine, phenylethylamine, and tryptamine. Guinea pig brain amine oxidase has a substrate specificity intermediate between those of rabbit and the other species.

The content of adenine nucleotides and creatine phosphate in brain of normal and anaesthetized rats: a critical study of some factors influencing their assay.

SPECIAL procedures are required in the analysis of labile phosphate compounds of brain because of the rapid breakdown of these substances during the manipulation of the animal prior to killing and before the enzymes of the brain are denatured by a protein precipitant (MCILWAIN, 1952). KERR (1935) observed that CP* levels in dog and cat brain were extremely low unless the animal was anaesthetized, the skull removed under artificial respiration, and liquid oxygen poured on the brain surface. With smaller animals, immersion of the whole animal in liquid air was required to obtain high levels of CP. LEPAGE (1 946a, b), using the immersion procedure, studied levels of labile phosphate compounds and carbohydrate intermediates in rat tissues, and found that animals which were not anasthetized with pentobarbitone before immersion possessed considerably lower brain levels of ATP and CP, and higher levels of ADP and AMP than those which had been anasthetized. MCILWAIN, BUCHEL, and CHESHIRE (1951) showed that if guinea pigs were decapitated and the brain was dropped into liquid oxygen within twenty seconds, there was almost complete disappearance of CP from the tissue. KRATZING and NARAYANASWAMI (1953), comparing whole body immersion with guillotining followed by immersion of the head, reporteda slight depletion of brain CP and ATP in guinea pigs. The number of animals employed was too small to permit evaluation of the sipficance of these differences. KORANSKY (1958), using the decapitation procedure, found considerably lower levels of labile phosphate compounds in rat brain than those reported by workers who killed animals by whole body immersion in liquid nitrogen. In the present report, an evaluation of some of the factors involved in the preservation and analysis of labile phosphate compounds of brain is attempted with the use of specific enzymic methods for the analysis of adenine nucleotides. The levels of labile phosphate compounds in etherand pentobarbitone-anasthetized rats and studies on the enzymes involved in their catabolism are presented.

Effect of chlorpromazine on levels of adenine nucleotides and creatine phosphate of brain.

~ U ~ W R O M A Z I N E is a tranquilizing agent which is capable of modifying a large number of metabolic processes. The drug is able to inhibit oxidative metabolism of brain homogenates (BERNSOHN, AMAJUSKA and COCHRANE, 1955; CENTURY and HORWTT, 1956; DECSI and MBHES, 1957; MESSER, 1958), slices (FINKLESTEIN, SPENCER and RIDGEWAY, 1954; RAU et al., 1956), and mitochondrial preparations (MD, 1955). The increased oxygen consumption of cortical slices due to electrical stimulation or potassium stimulation is especially sensitive to the presence of the drug (MCILWAIN and GREENGARD, 1957; LINDAN, QUASTEL and SVED, 19574. Chlorpromazine has been reported to inhibit several of the steps of the respiratory chain (BERGER, 1957), including DPNH-cytochrome c reductase (DAWKINS, JUDAH and RE=, 19596) and cytochrome oxidase (BERNSOHN et al., 1955; ABOOD, 1955; BERNSOHN, NAMAJUSKA and BOSHES, 1956; DAWKINS, JUDAH and REES, 19594. Several workers have demonstrated that the drug is capable of uncoupling oxidative phosphorylation, in some instances in concentrations which do not affect oxidative metabolism (CENTURY and HORWITT, 1956; DECSI and M~HES, 1957; ABOOD, 1955; ANDREJEW el al., 1956~). BERGER (1957) noted that oxidative phosphorylation in liver mitochondria was more sensitive to chlorpromazine than that in brain mitochondria, and concluded brain mitochondria1 effects were relatively nonspecific. However, DAWKINS et al. (1959a), using a somewhat different system, found that brain mitochondria were quite sensitive to the uncoupling action of chlorpromazine. M ~ E R (1958) concluded that reduced phosphorylation due to chlorpromazine was secondary to the depression of oxidative metabolism. Chlorpromazine is known to inhibit both aerobic and anaerobic glycolysis (BERNSOHN etal., 1955; ANDREEW and ROSENBERG, 1957). ATP-ascs are inhibited by the drug (ABO~D, 1955; ANDRETEW et al., 19566; BERNSOHN et a)., 1956; MESSER, 1958). In addition the drug has been reported to inhibit cholinesterases (BERNSOHN et al., 1956; ERDOS, BAART, SHANOR and FOLDES, 1958), glutamine synthesis (MESSER, 1958), the incorporation of glycine into protein (LINDAN, QUASTEL and SVED, 19573), D-amino acid oxidases (YAGI, NAGATSU and OZAWA, 1956; LASSLO and MEYER, 1959), and the turnover of brain phospholipid phosphorus (ANSELL and DOHMAN, 1956; RICHTER, 1957). The vast number of biochemical processes affected by chlorpromazine renders the elucidation of the primary pharmacological action of the drug exceedingly difficult. The reactions listed, however, can be grouped into two large categories: (1) those which are believed to be primarily involved in oxidative phosphorylation and the

Hyperlipoproteinemia and Cholesterol Deposition at the Arteries of I131-Treated Dogs.∗

Summary Dogs maintained for a year after I131 administration were found to achieve average maintenance levels of serum cholesterol in excess of 430 mg % and comparably elevated concentrations of other serum lipid and lipoprotein parameters. Tissue analysis at autopsy revealed significantly elevated levels of coronary artery, aorta, and liver cholesterol in male treated dogs, as compared with control males. Treated female dogs differed from treated males in developing significantly higher levels of Sf 0–12 blood lipoproteins, and slightly, possibly significantly, lower levels of coronary artery cholesterol. No correlation between altered tissue cholesterol content and any of the serum lipid or lipoprotein moieties was observed.