Analyses of adenosine and adenine nucleotides in biological materials by fluorescence reaction-high-performance liquid chromatography

A previous method of determination of adenine compounds by high-performance liquid chromatography, using bromoacetaldehyde as a fluorescent reagent and a column of Hitachi gel No. 3012-N, was improved and extended to biological materials, especially to measure enzyme activities. A column packed with finer beads, Hitachi gel No. 3013-N, was found to be better than that of No. 3012-N, judging from the analysis time and resolution. ADP, from the hydrolysis of ATP by Na, K-ATPase, was determined quantitatively, and the enzyme activity was inhibited with ouabain. cAMP obtained from ATP by reaction with adenylate cyclase was also determined in the presence of various concentrations of L-epinephrine or sodium fluoride. The ATP levels in human blood were determined, and the cellular levels of ATP and ADP in neuroblastoma N1E 115 were examined as a function of cell growth.

Decreased monoamine oxidase activity in stroke-prone spontaneously hypertensive rat kidneys

The present study was undertaken to measure kidney monoamine oxidase activity (MAO) isolated from three different rat groups: Wistar Kyoto rats (WKY), stroke-free cases of stroke-prone spontaneously hypertensive rats (SHRSP-control) and SHRSP-stroke cases (SHRSP-stroke). The SHRSP group was found to have less kidney MAO than the WKY group. Conversely, plasma norepinephrine concentration of SHRSP group was significantly higher than that of the WKY group (Jpn. Heart J., 25, 833-835, 1985). These findings suggest that the increased blood pressure in SHRSP may be related to increased plasma norepinephrine concentration caused by a decrease in degradation enzyme, MAO. An attempt was also made to determine the effects of clorgyline and deprenyl. No significant difference in MAO was observed between the kidneys isolated from the WKY, SHRSP-control and SHRSP-stroke groups. However, the inhibition curve of clorgyline reached a plateau after producing 33% inhibition of MAO. It was assumed that rat kidney mitochondrial MAO consists of 33% MAO-A type and 67% MAO-B type.

Myocardial ischemia stimulates catecholamine synthesis and catabolism in the dog adrenal medulla

The effects of regional ischemia of the myocardium upon metabolism and catabolism of catecholamines were studied in the dog adrenal medulla. Regional ischemia was induced by ligating a small branch of the left anterior descending coronary artery for 1 or 24 hours. Sham-operated controls were run in parallel. Coronary ligation for 24 hours resulted in a decrease in the level of epinephrine and an increase in the level of dopamine in the adrenal medulla, and also resulted in an increase in the activities of the phenylethanolamine-N-methyltransferase (PNMT), monoamine oxidase, and catechol-O-methyltransferase. The results after coronary ligation for 1 hour were essentially the same as those after coronary ligation for 24 hours, except that the activity of PNMT decreased. These results suggest that both synthesis and catabolism of catecholamines in the adrenal medulla are accelerated during coronary ligation for a period of 1 to 24 hours.

Simple purification of aromatic L-amino acid decarboxylase from human pheochromocytoma using high-performance liquid chromatography

We purified aromatic L-amino acid decarboxylase (AADC) homogeneously and rapidly from human pheochromocytoma using high-performance liquid chromatography. HPLC with gel permeation and hydrophobic columns was highly effective, and the entire purification could be finished within 3 days. Purified AADC showed a single band with an Mr of 50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and decarboxylated L-3,4-dihydroxyphenylalanine, L-5-hydroxytryptophan, and L-threo-3,4-dihydroxyphenylserine (a synthetic precursor of natural norepinephrine). Amino acid analysis of purified AADC was performed.

Natural variations in brain phenylethanolamine-N-methyltransferase activity during different phases of the oestrous cycle: effect of chronic dexamethasone treatment

The activity of phenylethanolamine-N-methyltransferase (PNMT) was studied in the hypothalamus, hypophysis, striatum and the rest of the brain during the four different phases of the oestrous cycle of the rat. The oestrous phase was marked by high level of enzyme activity in all the regions except the hypophysis. The hypophysis showed maximum increase in activity at the metoestrous phase of the oestrous cycle. Chronic treatment of rats with dexamethasone for 10 days led to decreased level of PNMT activity in the hypophysis, hypothalamus and the rest of brain. These decreases were important in the hypothalamus and the hypophysis which represented only 25 and 20% of the control activity after dexamethasone administration.

Probable role of reverse transcription in learning: correlation between hippocampal RNA-dependent DNA synthesis and learning ability in rats

The activities of RNA-dependent DNA polymerase and DNA-dependent DNA polymerase were measured in hippocampus of fast and slow learning Wistar rats. The RNA-dependent DNA polymerase activity in the hippocampus of fast learning rats exceeds two-fold that in the slow learning ones, while the rates of the DNA-dependent DNA polymerase activities are similar. A significant increase in RNA-dependent DNA polymerase only was found in the hippocampus of rats 20 min after training for the conditioned food response before the trace consolidation registered 40 min after the training session. The data obtained are consistent with the suggestion that reverse transcription plays an important role in memory consolidation.

Role of a non-ionic detergent upon maintenance and radioisotopic determination of enzymes catechol-O-methyltransferase and monoamine oxidase in brain and adrenal tissues

1. The effect of different concentrations of Triton-X-100, used as homogenization media for enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), was investigated. 2. Brain and adrenal COMT showed significant activation when treated with 0.2% Triton-X-100. 3. The activity of MAO in the brain and adrenal tissue was markedly inhibited by Triton-X-100 and the concentration required to provoke the inhibition was found to be much lower than that required to activate COMT. 4. When the tissues were kept in KCl-Triton-X-100 (0.9%-0.2%) for longer periods to study time related responses, brain COMT showed progressive increases in activity up to 4 hours of treatment and the increase persisted till 24 hours. Similar treatment of MAO enzyme preparation with Triton-X-100 induced strong inhibition of the enzyme activity (60% at 5 minutes and 55% at 24 hours). 5. The results suggest that the use of Triton-X-100 should be considered with extra care for determination of catecholamine regulating enzymes. It can activate one enzyme system whereas inhibit the other one. Therefore, different homogenization medias are required for the assay of enzymes of metabolism (MAO and COMT) and synthesis (tyrosine hydroxylase, phenylethano-l-amine-N-methyltransferase and dopamine beta hydroxylase).

Enzymes for epinephrine synthesis and metabolism in the myometrium, endometrium, red blood cells, and plasma of pregnant human subjects

The enzyme phenylethanolamine-N-methyl transferase (PNMT) converts norepinephrine (NE) to epinephrine (E), and cathechol-O-methyl transferase (COMT) and monoamine oxidase (MAO) both metabolize NE and E. We were able to measure the activity of these enzymes in myometrial and endometrial samples obtained from 27 pregnant women between 32 and 40 weeks' gestation at the time of cesarean section. In addition, these enzymes were measured in red blood cells and plasma obtained from 45 normal pregnancies between 10 and 40 weeks' gestation. PNMT activity was significantly higher in myometrium than in endometrium. During labor myometrial and red blood cell PNMT activity is significantly lower than in specimens from patients at term not in labor, while myometrial PNMT activity is significantly elevated in patients with dystocia. Under these conditions no significant alterations in myometrial, red blood cell, or plasma COMT or myometrial MAO activities were observed. This study identifies for the first time the presence of PNMT in myometrium, endometrium, and red blood cells and provides the necessary step for the conversion of NE to E, a concept previously limited to the adrenal bland, brain, and heart. This could provide an important physiologic mechanism for the control of uterine activity during pregnancy and parturition.

Regulation of central and peripheral carbohydrate reserves after selective inhibition of enzyme monoamine oxidase: comparison between fed and starved rats

1. Maintenance of brain, liver and heart glycogen after selective inhibition of enzyme monoamine oxidase with clorgyline and deprinil was studied in normally fed or starved rats. 2. The administration of clorgyline to fed rats produces an important decrease in glycogen of the brain after 3 h of injection whereas the same treatment to starved rats resulted in complete exhaustion of brain glycogen stores. 3. Deprinil administration provoked a complete disappearance of glycogen in brain in fed rats after one and three hours of the injection but the same dose given to starved rats had a similar effect only after one hour since three hours after brain glycogen reserves of starved rats were close to the control values. 4. Clorgyline did not modify hepatic glycogen in fed rats but in starved rats in increase after three hours of administration took place. 5. Deprinil decreased liver glycogen in fed rats but the starved rats showed increases after one and three hours. 6. Heart glycogen increased in fed rats after clorgyline injection but starved rats showed slight decreases. Deprinil decreased cardiac glycogen slightly in fed as well as starved rats. 7. After one hour of deprinil injection glycemia was at the lowest value in fed rats but the decrease in starved rats was less marked. Three hours after deprinil or clorgyline administration both groups showed increases in glycemia. 8. Marked differences in the degree of MAO inhibition between fed and starved rats were observed after clorgyline and deprinil administration. The brain of starved rats showed only 49% inhibition whereas fed rats had 91% enzyme inhibition after three hours of deprinil treatment.

Influence of the hypophysio-adrenocortical system on the metabolism of 3H-adrenaline in the hypothalamus, hypophysis and the rest of the brain of rats

Possible correlation between modified state of the adrenocortical system and the metabolic fate of 3H-adrenaline in central regions was studied. The formation of 3H-acid metabolites from 3H-adrenaline showed high increase in brain and hypothalamus of hypophysectomized rats from the value of normal animals. Adrenalectomy was also found to be associated with increased acid metabolite formation in the whole of the brain. Preadministration of metopirone increased formation of acid metabolites in the hypothalamus and hypophysis of normal rats. The transformation of radioactive normetanephrine was significantly higher in the hypothalamus of rats administered with elliptone as well as with metopirone. The hypophysis showed increase in metanephrine formation only by pretreatment with elliptone. Brain tissue demonstrated increased rate of normetanephrine formation after adrenalectomy and hypophysectomy. Hypophysectomy increased physiological accumulation of 3H-adrenaline in all the three regions studied but the maximal effect was observed in the hypothalamus. The preadministration of elliptone and metopirone decreased accumulation of labeled adrenaline in the brain and hypophysis of normal rats. The results suggest that inactivation of adrenocortical system either pharmacologically or physiologically leads to activation of the the processes of catecholamine metabolic degradation whereas the physiological accumulation of adrenaline slows down and this conclusion is valid for a great majority of observations presented in this study.

Variations in mitochondrial monoamine oxidase during progressive starvation in the brain of developing rats

Effects of progressive starvation of 12, 24, 48 and 60 h upon brain mitochondrial monoamine oxidase activity were studied. The enzyme activity was determined by three different substrates: 14C-labeled tryptamine, dopamine and kynuramine. With dopamine as substrate, the enzyme activity showed decline during 24 and 48 h of starvation. Monoamine oxidase when determined by tryptamine as the substrate, showed a decrease after 60 h of starvation. The use of kynuramine as substrate also produced a decrease in enzyme activity after 48 and 60 h of starvation. Refeeding the 60-h-starved rats for the following 24 h resulted in further decrease of monoamine oxidase activity of brain mitochondria from the 60 h starved values. The results suggest that oxidative deamination of biogenic amines is greatly inhibited during progressive starvation and remains low even after feeding the 60 h starved rats for 24 h.

Developmental changes in the activity of catechol-O-methyl transferase in rat and rabbit fetuses

Variations in the activity of catechol-O-methyltransferase (COMT) in peripheral organs in the brain of rat and rabbit fetus during development have been studied. The pattern of changes in COMT activity in rat fetus differed to a great extent according to the respective organs studied. In kidney and liver sharp declines occurred between days 18 and 20 and days 16 and 18 of fetal life respectively, followed by progressive increases up to onset of birth. Brain COMT of rat fetus declined progressively from day 16 of fetal life up to 0 hours after birth, while COMPT activity in adrenal and heart showed its maximum value at the 20th day of fetal life and at 0 hours after birth respectively. In the contrary, the developmental changes in activity of rabbit fetus were very similar in all the organs except in the adrenals, since it decreased between day 24 to 8 hours after birth in heart, liver, brain and kidney. In the adrenals an important increase could be seen between the 24th and 28th days of fetal life. Rat COMT activity during 4 and 8 hours of postnatal life in heart, liver and kidney declined from 0-hour value but it increased in the brain and adrenals. COMT in rabbit increased after birth in all the organs studied. The results suggest that metabolic degradation of catecholamines by 3-O-methylation in rat and rabbit fetus may have different developmental patterns to some extent according to the physiological status of the organ concerned. These species related differences for monoamine inactivation during fetal development may suggest a physiological role for COMT as a marker of the maturation of the autonomic nervous system.

Influence of progressive starvation upon brain and adrenal monoaminergic activity in developing rats of two different ages

Experiments show the influence of progressive starvation upon the synthetic and metabolic activity of monoaminergic function in the brain and the adrenal gland of young rats of two different ages. Brain and adrenal monoamine oxidase (MAO) showed a tendency to decline with the prolongation of the starvation interval. After 60 h of starvation, MAO activity was irreversibly decreased, even with 24 h of feeding, in the two age groups. Cerebral catechol-O-methyltransferase (COMT) activity was very slightly affected in response to the starvation in the older group, but the younger group showed an increased level of enzyme activity, and refeeding after 60 h of starvation of the young rats produced further increases. 60 h of starvation produced an increase in COMT activity of the adrenal gland of the older rats whereas the younger group did not show any marked change. Adrenal phenylethanolamine-N-methyltransferase (PNMT) declined after 24 and 48 h of starvation in the older rats, but the younger rats showed progressive increases after similar intervals of starvation. After 60 h of starvation, PNMT in the adrenal gland of the old rats increased significantly when compared to the control value, but the younger rats did not show any important change. Adrenal stores of adrenaline rose progressively up to 60 h of starvation in the old rats whereas the younger group responded in a contrary manner. Adrenal noradrenaline followed a similar pattern of evolution in both groups up to 60 h of starvation (when the results are expressed per milligram of adrenal protein), and refeeding had very little influence on the effects of starvation. The effects of starvation upon adrenal and cerebral MAO activity were verified with two different substrates. The results provide evidence that the metabolism of monoamines by oxidative deamination can be markedly affected by starvation, and this can be irreversible even after 24 h of feeding of starved rats. COMT activity augments when MAO activity declines.

Fate of vasoactive biogenic amines and activity of enzyme phenylethanolamine-N-methyltransferase in rat adrenal gland during the course of pregnancy, parturition and postpartum

Influence of pregnancy, parturition and postparturition upon natural evolution of adrenaline, dopamine and enzyme of adrenaline synthesis, phenylethanolamine-N-methyltransferase in the adrenal gland was studied. Adrenaline content of the adrenal gland showed a progressive decrease from the 14th to the 18th day postcoitum. The mean values for adrenaline remained lower than the value of day 14 throughout the course of pregnancy up to day 21 postcoitum. At parturition (0 to 4 h) adrenaline declined again to its minimum value but was accompanied by an increase in the adrenal adrenaline level 24 h postpartum. The activity of enzyme phenylethanolamine-N-methyltransferase followed a similar pattern of evolution as that of adrenaline during pregnancy and postpartum. Dopamine concentration of the adrenal gland showed nonsignificant increases during days 14--18 postcoitum. At day 20 postcoitum adrenal dopamine was decreased to its minimum value and this decrease persisted up to day 21 postcoitum. At day 22 postcoitum, adrenal dopamine increased sharply to its maximum value but was again back to the level of day 21 at 0 h parturition. At 24 h postpartum, dopamine content decreased maximally again. The results presented here suggest that the content of vasoactive biogenic amines and the enzyme of adrenaline synthesis go through important natural variations during pregnancy, parturition and postpartum from day 14 postcoitum to 24 h postpartum. This phenomenon does not seem to be merely a cyclic effect. All these variations can be attributed to modified endocrine activity of the pregnant animals by correlating natural variations in steroid hormone levels with the observed changes in biogenic amines, since it is well established that most of the hormonal and nonhormonal steroids affect catecholamine regulation. The observed changes in amine levels could have important influence for the termination of pregnancy.

Maintenance of central and peripheral monoamine oxidase activity in developing rats subjected to disturbed alimentary rhythms and undernutrition

Monoamine oxidase (MAO) activity was studied in whole brain, hypothalamus, adrenals and liver of developing rats subjected to disturbed feeding patterns or undernutrition for 3 weeks. The rats were divided into six groups: (1) normally fed controls; (2) rats starved for 24 h, fed for the following 8 h and killed after the last starvation period (PAS); (3) same treatment as in (2) but killed after the last feeding period (PAF); (4) rats starved for 16 h, fed for the following 8 h at a constant schedule, and killed after the last starvation period (PS); (5) same treatment as in (4) but killed after the last feeding period (PF), and (6) undernourished (U). Alteration of the feeding time resulted in significant decreases of MAO activity in the brain and the adrenal gland whereas the hypothalamus and the liver showed a slight increase in activity in the PAS group. In PS rats, MAO activity increased in the brain, adrenals and hypothalamus; in PF rats, the effects of the treatment were inverse. Both in the PS and PF rats, hepatic MAO activity was strongly decreased when assayed with kynuramine. In U rats, hepatic MAO activity was highly increased when assayed with kynuramine but the other tissues responded differently. The adrenaline and noradrenaline stocks of the adrenal gland were markedly increased in all the treated groups; the maximum increase in noradrenaline was observed in the PS rats. The results suggest that any disturbance in the feeding pattern affects the MAO activity in the central and peripheral regions of the young rat during postnatal development. The developing rat seems to get accustomed to new alimentary rhythms, and normal monoaminergic function is rapidly restored when the rat is given a compensatory diet. Increased adrenal catecholamines after a disturbance in the feeding patterns seem to be a response to stress.

Effects of cortisol on adrenal phenylethanolamine-N-methyltransferase: antagonistic effects of vitamin D in hypophysectomized rats fed a vitamin D free diet

The influence of individual or combined administration of vitamin D and hydrocortisone on adrenal phenyl-N-methyltransferase (PNMT) in hypophysectomized rats deprived of vitamin D for 1 month has been studied, as well as adrenal and urinary epinephrine and norepinephrine. Daily administration of vitamin D for 11 days decreased PNMT activity and increased adrenal norepinephrine, whereas adrenal epinephrine remained unaffected. Epinephrine and norepinephrine urinary excretion increased after four and nine injections of vitamin D from the hypophysectomized rats fed a vitamin D free diet for 1 month. Hydrocortisone treatment produced increases in adrenal PNMT and epinephrine as well as in urinary excretion of both monoamines. The effects of individual administration are neutralized when the two products are injected together.

Central and peripheral catecholamines and phenylethanolamine-N-methyl-transferase activity during the oestrus cycle

Natural variations in monoamine levels in the adrenal gland, whole brain, hypothalamus and plasma during the oestrus cycle were determined in Sherman rats. Noradrenaline content of adrenal gland was at its highest level during met-oestrus phase while adrenaline was at its lowest level. During pro-oestrus adrenaline in the adrenal gland was at the maximum value. Plasma adrenaline did not change significantly during the oestrus cycle. However plasma noradrenaline was significantly higher during metoesrus compared to the value of di-oestrus and pro-oestrus. In the hypothalamus noradrenaline level was at its highest value during di-oestrus and at its lowest during met-oestrus, while brian noradrenaline reached its maximum value during pro-oestrus. The sum of plasma adrenaline and noradrenaline showed maximum level during met-oestrus phase but at the same time total adrenal adrenaline plus noradrenaline was lowered. The variations in adrenaline and noradrenaline in the adrenal gland did not correspond to the changes in the activity of enzyme, phenylethanolamine-N-methyltransferase (PNMT). The activity of PNMT reached its maximum value during met-oestrus phase of the oestrus cycle. The observed variations in adrenal, brain, hypothalamus and plasma catecholamines can be attributed to the modification in endocrine activity which takes place during the oestrus cycle.