Clinical Catecholamine Neurochemistry: A Legacy of Julius Axelrod

1. Discoveries, insights, and concepts that Julius Axelrod introduced about the disposition and metabolism of catecholamines provided the scientific basis and spurred the development of clinical catecholamine neurochemistry.2. Here, we provide examples of this aspect of Axelrod's scientific legacy.     

Effect of Global Ischaemia, Under Simulated Penumbral Conditions, on Brain Monoamine Neurochemistry and Subsequent Neurological and Histological Deficits

Abstract— We have measured changes in the levels of do-pamine (DA), 5-hydroxytryptamine (5-HT), and their metabolites in striatal dialysates during 30 min of global ischaemia under simulated penumbral conditions, and compared these with neurological assessments over the following 7 days and histological damage at the end of this period. On the basis of dialysate DA levels during ischaemia, the animals fell into two subgroups; group I, with little or no DA increase (less than three times basal); and group II, with a much larger increase (greater than 30 times basal). Changes in 5-HT, though of lesser magnitude, showed a similar pattern. These findings may indicate that the amine changes depend on a critical reduction of blood flow within the range obtained by our experimental procedure. Levels of deaminated metabolites fell in all ischaemic animals, with comparable decreases of 3, 4-dihydroxyphenylacetic acid plus homovanillic acid in both groups. Decreases of 5-hydroxyindoleacetic acid were greater in group II than in group I, but the relative differences between the groups were much less marked than those of 5-HT. These neuro-chemical findings suggest that moderate ischaemia affects extracellular amine and deaminated metabolite levels by different mechanisms. Only one of the ischaemic rats (a member of group II) showed a marked neurological deficit, but histological damage, as indicated by neuronal loss and gliosis in vulnerable structures, was apparent in all ischaemic animals. Although damage tended to be greater in animals with marked increases in extracellular monoamines, differences were not significant. These findings suggest that the large increases of extracellular DA and 5-HT that sometimes occur in ischaemia may play a relatively small part in the genesis of neuronal damage, though these transmitters may well have a permissive role.     

Winter growth of juvenile plaice on the Port Erin Bay (Isle of Man) nursery ground

Juvenile plaice ( Pleuronectes platessa ) were studied in Port Erin Bay, Isle of Man, U.K. between September and March 1989/1990 and 1990/1991. Plaice (>90 mm) were tagged and individual growth rates calculated for the autumn, winter and over-winter time periods. During the study the population of fish >90 mm remained fairly stable both within a study season and between years. Autumn growth rates ranged from 0 to 0.39 mm day⁻¹ (mean₁₉₈₉=0.13 mm day⁻¹, mean₁₉₉₀=0.10 mm day ⁻¹) and winter 0 to 0.5 mm day⁻¹ (mean₁₉₉₀=0.11 mm day⁻¹ and mean₁₉₉₁=0.17 mm day ⁻¹). In general, growth rates were higher at higher mean seasonal temperatures. However, relative growth rate was significantly higher in the colder winter period of 1991 than 1990.     

Effects of insulin and streptozotocin-induced diabetes on brain tryptophan and serotonin metabolism in rats

Previous work by other authors has shown hat insulin administration increases brain tryptophan levels and serotonin (5–HT) metabolism. The present study partially replicates these results and tests whether these effects could be due to insulin-induced hypoglycemic stress, since stressers such as immobilization or food deprivation also increase brain tryptophan and 5-HT metabolism. Ingestion of a dextrose solution by rats administered insulin (2 I.U./kg) prevents the extreme fall in blood glucose concentration and rise in plasma corticosterone following insulin injections alone. This treatment, however, produces a larger increase in brain tryptophan (30%) than insulin-injected rats allowed only tap water. The greater accumulation of brain tryptophan may reflect an additive effect of the endogenously released insulin to that exogenously administered, since ingestion of the dextrose solution could trigger insulin secretion. In addition, brain tryptophan and 5-HT metabolism were measured in streptozotocin-diabetic rats maintained on several different feeding schedules to control for the effects of hyperphagia. All groups of diabetics showed significant decreases of approx 30% in brain tryptophan concentrations, while 5-HT metabolism was unchanged. This deficit in brain tryptophan is reversed within 2 h after insulin administration (2 I.U./kg). These results indicate that changes in brain tryptophan and 5-HT metabolism following insulin injections are not due to hypoglycemic stress, and that brain tryptophan is low in diabetics but increases above normal after administration of insulin. The results are discussed with respect to the effects of insulin on plasma levels of the neutral amino acids and a possible direct effect of insulin on the uptake of tryptophan by brain.     

Effect of psychotropic drugs on 3,4-dihydroxyphenylacetic acid (DOPAC) content in the medial basal hypothalamus

The effect of different psychotropic drugs on 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the medial basal hypothalamus has been studied by the use of a very sensitive radioenzymatic method. Apomorphine and haloperidol, which are known to respectively decrease and increase DOPAC levels in the caudate nucleus, fail to influence DOPAC level in the medial basal hypothalamus. Reserpine, which increases DOPAC level in the caudate nucleus, decreases it in the medial basal hypothalamus. Amphetamine decreases DOPAC level in the medial basal hypothalamus as it does in the caudate nucleus. These results suggest that DA metabolism in the medial basal hypothalamus is controlled by mechanisms different from those operating in other brain areas.     

Changes in the Amino Acid Content of Nerve Endings (Synaptosomes) Induced by Drugs that Alter the Metabolism of Glutamate and γ-Aminobutyric Acid

The study was centered on the changes in the amino acid content of nerve endings (synaptosomes) induced by drugs that alter the metabolism of glutamate or gamma-aminobutyric acid (GABA), and that possess convulsant or anticonvulsant properties. The onset of seizures induced by various convulsant agents was associated with a decreased content of GABA and an increased content of glutamate in synaptosomes. The concurrent administration of pyridoxine prevented both the biochemical changes and the convulsions. The administration of gabaculine to mice resulted in large increases in the GABA content of synaptosomes that were counteracted by decreases in glutamate, glutamine, and aspartate levels such that the total content of the four amino acids remained unchanged. The administration of aminooxyacetic acid (0.91 mmol/kg) resulted initially in seizure activity, but subsequently in an anticonvulsant action. No simple relationship existed between the excitable state of the brain induced by aminooxyacetic acid and the changes in the synaptosomal levels of any of the amino acid transmitters. A hypothesis was, however, formulated that explained the convulsant-cum-anticonvulsant action of aminooxyacetic acid on the basis of compartmentation of GABA within the nerve endings.     

Retinal Amino Acid Neurochemistry of the Southern Hemisphere Lamprey,Geotria australis

Lampreys are one of the two surviving groups of the agnathan (jawless) stages in vertebrate evolution and are thus ideal candidates for elucidating the evolution of visual systems. This study investigated the retinal amino acid neurochemistry of the southern hemisphere lamprey Geotria australis during the downstream migration of the young, recently-metamorphosed juveniles to the sea and during the upstream migration of the fully-grown and sexually-maturing adults to their spawning areas. Glutamate and taurine were distributed throughout the retina, whilst GABA and glycine were confined to neurons of the inner retina matching patterns seen in most other vertebrates. Glutamine and aspartate immunoreactivity was closely matched to Müller cell morphology. Between the migratory phases, few differences were observed in the distribution of major neurotransmitters i.e. glutamate, GABA and glycine, but changes in amino acids associated with retinal metabolism i.e. glutamine and aspartate, were evident. Taurine immunoreactivity was mostly conserved between migrant stages, consistent with its role in primary cell functions such as osmoregulation. Further investigation of glutamate signalling using the probe agmatine (AGB) to map cation channel permeability revealed entry of AGB into photoreceptors and horizontal cells followed by accumulation in inner retinal neurons. Similarities in AGB profiles between upstream and downstream migrant of G. australis confirmed the conservation of glutamate neurotransmission. Finally, calcium binding proteins, calbindin and calretinin were localized to the inner retina whilst recoverin was localized to photoreceptors. Overall, conservation of major amino acid neurotransmitters and calcium-associated proteins in the lamprey retina confirms these elements as essential features of the vertebrate visual system. On the other hand, metabolic elements of the retina such as neurotransmitter precursor amino acids and Müller cells are more sensitive to environmental changes associated with migration.     

Effect of Transient Cerebral Ischaemia and Cardiac Arrest on Brain Extracellular Dopamine and Serotonin as Determined by In Vivo Dialysis in the Rat

The effects of 20-min transient, global, forebrain ischaemia and cardiac arrest on extracellular concentrations of dopamine (DA), serotonin (5-HT), and their respective metabolites, homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), were measured in vivo by dialysis of rat striatum and hippocampus. During the ischaemic period, striatal DA content increased (250-fold basal concentrations) with parallel but much less marked increases of both striatal and hippocampal 5-HT content (eight- to 10-fold). Baseline values were restored during reperfusion. Subsequent increases of DA and 5-HT levels on cardiac arrest were comparable after both sham operation and ischaemia. Significant decreases of HVA and 5-HIAA levels were observed following ischaemia or cardiac arrest. The differential effects of ischaemia on DA and 5-HT suggest selective alterations in disposition or metabolism of the two transmitters and that dopaminergic neurones may be more vulnerable to ischaemic insults.     

Algorithms to predict cerebral malaria in murine models using the SHIRPA protocol

Background

Metabolic changes in the host in response to Plasmodium infection play a crucial role in the pathogenesis of malaria. Alterations in metabolism of male and female mice infected with Plasmodium berghei ANKA are reported here.

Methods

¹H NMR spectra of urine, sera and brain extracts of these mice were analysed over disease progression using Principle Component Analysis and Orthogonal Partial Least Square Discriminant Analysis.

Results

Analyses of overall changes in urinary profiles during disease progression demonstrate that females show a significant early post-infection shift in metabolism as compared to males. In contrast, serum profiles of female mice remain unaltered in the early infection stages; whereas that of the male mice changed. Brain metabolite profiles do not show global changes in the early stages of infection in either sex. By the late stages urine, serum and brain profiles of both sexes are severely affected. Analyses of individual metabolites show significant increase in lactate, alanine and lysine, kynurenic acid and quinolinic acid in sera of both males and females at this stage. Early changes in female urine are marked by an increase of ureidopropionate, lowering of carnitine and transient enhancement of asparagine and dimethylglycine. Several metabolites when analysed individually in sera and brain reveal significant changes in their levels in the early phase of infection mainly in female mice. Asparagine and dimethylglycine levels decrease and quinolinic acid increases early in sera of infected females. In brain extracts of females, an early rise in levels is also observed for lactate, alanine and glycerol, kynurenic acid, ureidopropionate and 2-hydroxy-2-methylbutyrate.

Conclusions

These results suggest that P. berghei infection leads to impairment of glycolysis, lipid metabolism, metabolism of tryptophan and degradation of uracil. Characterization of early changes along these pathways may be crucial for prognosis and better disease management. Additionally, the distinct sexual dimorphism exhibited in these responses has a bearing on the understanding of the pathophysiology of malaria.     

Macronutrients and obesity: Revisiting the calories in,calories out framework

Recent clinical research has studied weight responses to varying diet composition, but the contribution of changes in macronutrient intake and physical activity to rising population weight remains controversial. Research on the economics of obesity typically assumes a “calories in, calories out” framework, but a weight production model separating caloric intake into carbohydrates, fat, and protein, has not been explored in an economic framework. To estimate the contributions of changes in macronutrient intake and physical activity to changes in population weight, we conducted dynamic time series and structural VAR analyses of U.S. data between 1974 and 2006 and a panel analysis of 164 countries between 2001 and 2010. Findings from all analyses suggest that increases in carbohydrates are most strongly and positively associated with increases in obesity prevalence even when controlling for changes in total caloric intake and occupation-related physical activity. Our structural VAR results suggest that, on the margin, a 1% increase in carbohydrates intake yields a 1.01 point increase in obesity prevalence over 5 years while an equal percent increase in fat intake decreases obesity prevalence by 0.24 points.     

Effects of Endogenous Glutamate on Extracellular Concentrations of GABA, Dopamine, and Dopamine Metabolites in the Prefrontal Cortex of the Freely Moving Rat: Involvement of NMDA and AMPA/KA Receptors

Using microdialysis, interactions between endogenous glutamate, dopamine, and GABA were investigated in the medial prefrontal cortex of the freely moving rat. Interactions between glutamate and other neurotransmitters in the prefrontal cortex had already been studied using pharmacological agonists or antagonists of glutamate receptors. This research investigated whether glutamate itself, through the increase of its endogenous extracellular concentration, is able to modulate the extracellular concentrations of GABA and dopamine in the prefrontal cortex. Intracortical infusions of the selective glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) were used to increase the endogenous extracellular glutamate. PDC (0.5, 2, 8, 16 and 32 mM) produced a dose-related increase in dialysate glutamate in a range of 1–36 M. At the dose of 16 mM, PDC increased dialysate glutamate from 1.25 to 28 M. PDC also increased extracellular GABA and taurine, but not dopamine; and decreased extracellular concentrations of the dopamine metabolites DOPAC and HVA. NMDA and AMPA/KA receptor antagonists were used to investigate whether the increases of extracellular glutamate were responsible for the changes in the release of GABA, and dopamine metabolites. The NMDA antagonist had no effect on the increase of extracellular GABA, but blocked the decreases of extracellular DOPAC and HVA, produced by PDC. In contrast, the AMPA/KA antagonist blocked the increases of extracellular GABA without affecting the decreases of extracellular DOPAC and HVA produced by PDC. These results suggest that endogenous glutamate acts preferentially through NMDA receptors to decrease dopamine metabolism, and through AMPA/KA receptors to increase GABAergic activity in the medial prefrontal cortex of the awake rat.     

A History of the Origin and Development of Japanese Society for Neurochemistry: International Cooperation to Overcome Dementia and Mental Illness

“Neurochemistry” in Japan was established by intensive cooperation between psychiatrists and their collaborators, biochemists, who have sought to investigate the etiology of mental illness to establish treatments. It was a completely different direction from the flow of modern biochemistry that was born using microorganisms or eukaryotic cells as research materials. Neurochemists aimed to elucidate the physiological or pathological functions of the brain through chemical analysis of the morphologically and functionally unique complexity and characteristics of brain. I here describe some of the origin and history of neurochemistry in Japan how researchers estabIished Japanese Society for Neurochemistry in1958 Yasuzo Tsukada as a president in collaboration with Isamu Sano, Genkichiro Takagaki and Masanori Kurokawa. The formation of research groups with the support of MEXT played a major role in promoting neurochemistry. Many international conferences held in Japan promoted the activity of neurochemistry: The International Society of Physiology (Tokyo) in 1965, and the Japan-US Neurochemistry Conference (Oiso) in 1965, and in 1967 the International Conference on Biochemistry (Tokyo). These meetings offered excitements to younger researchers by close interaction with the world top class researchers. Government established Brain Research Institutes in several national universities. The Asia–Pacific Society for Neurochemistry (APSN) was established in 1991 subsequent to an initiative by JSN. APSN presidents: Yasuzo Tsukada, Kazuhiro Ikenaka, and Akio Wanaka contributed to promote neurochemistry. The 4th ISN meeting was organized at Tokyo (Yasuzo Tsukada, president) in 1973 and the 15th ISN meeting at Kyoto (Kinya Kuriyama, president) in 1995. Kunihiko Suzuki and Kazuhiro Ikenaka as ISN Presidents greatly contributed in promoting the activity of ISN.

     

Progress toward Global Reduction in Under-Five Mortality: A Bootstrap Analysis of Uncertainty in Millennium Development Goal 4 Estimates

Background

Millennium Development Goal 4 calls for an annual rate of reduction (ARR) of the under-five mortality rate (U5MR) of 4.4% between 1990 and 2015. Progress is measured through the point estimates of the United Nations Inter-agency Group for Child Mortality Estimation (UN IGME). To facilitate evidence-based conclusions about progress toward the goal, we assessed the uncertainty in the estimates arising from sampling errors and biases in data series and the inferior quality of specific data series.

Methods and Findings

We implemented a bootstrap procedure to construct 90% uncertainty intervals (UIs) for the U5MR and ARR to complement the UN IGME estimates. We constructed the bounds for all countries without a generalized HIV epidemic, where a standard estimation approach is carried out (174 countries). In the bootstrap procedure, potential biases in levels and trends of data series of different source types were accounted for. There is considerable uncertainty about the U5MR, particularly for high mortality countries and in recent years. Among 86 countries with a U5MR of at least 40 deaths per 1,000 live births in 1990, the median width of the UI, relative to the U5MR level, was 19% for 1990 and 48% for 2011, with the increase in uncertainty due to more limited data availability. The median absolute width of the 90% UI for the ARR from 1990 to 2011 was 2.2%. Although the ARR point estimate for all high mortality countries was greater than zero, for eight of them uncertainty included the possibility of no improvement between 1990 and 2011. For 13 countries, it is deemed likely that the ARR from 1990 to 2011 exceeded 4.4%.

Conclusions

In light of the upcoming evaluation of Millennium Development Goal 4 in 2015, uncertainty assessments need to be taken into account to avoid unwarranted conclusions about countries'' progress based on limited data. Please see later in the article for the Editors'' Summary     

Experimental induction of luteal cyclicity in roe deer (Capreolus capreolus).

Concentrations of progesterone and luteinizing hormone in plasma were analysed for two consecutive years in samples from nonpregnant female roe deer. Three animals were treated with monthly prostaglandin injections (325 micrograms cloprostenol) from October 1989 to April 1990 and from October 1990 to March 1991, and three were kept as controls. In control animals, a small increase in progesterone concentrations in July 1990 occurred at the same time as the commencement of the rut in other husbanded roe deer. In prostaglandin-treated animals, progesterone concentration was high at the time of the rut and remained so until late February 1990. After the next rut (August 1990), progesterone concentration remained high until March 1991. Between October and February-March, injections of prostaglandins induced dramatic, but temporary (lasting 72 h), decreases in plasma progesterone concentrations, indicating luteal regression and subsequent ovulation. We infer that roe deer can ovulate repeatedly and should therefore not be regarded as an obligate monoestrous species.     

Acoustic telemetry to assess post-stocking dispersal and mortality of razorback sucker Xyrauchen texanus

Acoustic telemetry and scuba revealed immediate and high post-stocking mortality of razorback sucker Xyrauchen texanus in Lake Mohave, U.S.A., a Colorado River impoundment. At the conclusion of this 6 month study, only three of 19 (16%) study fish remained active. Concurrently, 20 X. texanus implanted with acoustic transmitters and held in a hatchery raceway remained healthy throughout the experiment and no transmitters were shed. Post-stocking mortality was probably due to predation by striped bass Morone saxatilis , a piscivorous non-native fish.     

血液循环在大脑信息处理过程中的时序控制作用

自2006年以来,作者已陆续在一些杂志,网站和学术会议[1-3]上发表一些文章和证据,主要探究如下几个问题:(1)讨论各种脑电波现象的起源,大脑信息处理过程,血液循环三者之间关系.(2)提出了血液循环在大脑处理信息的过程中起到了基础时钟的作用;提出其可能的一个分子机制,其中H 浓度,O2浓度,微循环系统的工作机制,NMDA受体的H 位点是几个关键因素.(3)大脑如何感知时间的生理机制.提出时间感(或者时间流逝感)其实是一种压感,来源于当血液流经大脑的血管网的时候,造成的压感;而大脑对连续物理过程的感知则是大脑中记录情景(照片)的一个细胞群序列兴奋的信号和压感通过"捆绑效应"整合给人的感觉(即有点像放电影).在本文中,将对这些观点和证据进行回顾:文章第1节在整体上叙述所建立的脑电波模型,和"血液循环在大脑处理信息上具有时序控制作用"的观点.第2～5节将从各方面给出支持第1节中所叙述模型和观点的证据,并对一些问题进行澄清.第6～8节将该模型应用于解释一些脑电波和神经生理现象,解决目前一些问题(例如α波的起源问题,睡眠的脑电现象等).     

The European Weed Research Society and the Management and Ecology of Freshwater Plants

Attendance at the 9th International Symposium on Aquatic Weeds, held in Dublin in 1994, by 270 delegates from 35 different countries demonstrated the continuing interest in the management and ecology of freshwater plants. The relative importance of the various topics covered in this meeting is compared with that of the previous symposia (1967–1990) for which published proceedings are available. A shift of interest away from aquatic weed control towards ecology, plant-environment interactions and distribution is noted and demonstrates a growing recognition of the need for aquatic plant management. The interest in physical control has remained constant (5–12% of papers) whilst the interest shown in biological control over the period 1971 to 1982 has not been sustained in recent symposia. The international nature of the symposia has increased over the years with papers published rising from eight countries in the 1967, 1971 and 1974 symposia to 23, 18 and 20 in the last three. Consistent numbers of contributions have been made by delegates from the Netherlands, the Czech Republic and the United Kingdom with a significant and sustained increase since 1967 from the United States of America.     

Unloading-induced remodeling in the normal and hypertrophic left ventricle

To date, no study has assessed the degree of similarity between left ventricular (LV) reverse remodeling and atrophic remodeling. Stable LV hypertrophy was induced by creation of an arteriovenous fistula (AVF) in Lewis rats (32 days). LV unloading was induced by heterotopic transplantation of normal (NL-HT) and/or hypertrophic (AVF-HT) hearts (7 days). We compared indexes of remodeling in AVF, NL-HT, and AVF-HT groups with those of normal controls. LV unloading induced decreases in cardiomyocyte size in NL-HT and AVF-HT hearts. NL-HT and AVF-HT LV were both characterized by relative increases in collagen concentration that were largely a reflection of decreases in myocyte volume. NL-HT and AVF-HT LV were associated with similar increases in matrix metalloproteinase (MMP-2 and -9) zymographic activity, without change in the abundance of the tissue inhibitors of the MMPs. In contrast, AVF-HT, but not NL-HT, was associated with a dramatic increase in collagen cross-linking. Our findings suggest an overall similarity in the response of the normal and hypertrophic LV to surgical unloading. However, the dramatic increase in collagen cross-linking after just 1 wk of unloading suggests a potential difference in the dynamics of collagen metabolism between the two models. Further studies will be required to determine the precise molecular mechanisms responsible for these differences in extracellular matrix regulation. However, with respect to these and related issues, heterotopic transplantation of hypertrophied hearts will be a useful small animal model for defining mechanisms of myocyte-matrix interactions during decreased loading conditions.     

Thrombin's effects on osteoblastic cells. I. Cytosolic calcium and phosphoinositides

Thrombin, a blood coagulation factor, has been shown to be a very effective in vitro bone resorbing agent whose mechanism of action on osteoblastic cells remains to be elucidated. In the present study, the effects of highly purified human thrombin on Saos-2 and G292 cells, two human osteoblast-like osteosarcoma cell lines, were investigated. Thrombin (0.6-16 U/ml) caused a significant, dose-dependent increase in osteoblastic cell proliferation. Thrombin also elicited a dose-dependent increase in cytosolic calcium concentration in both Saos-2 and G292 cells (maximal increases were 38% and 200% over baseline, respectively). Addition of thrombin to the osteoblast-like cells resulted in significant time- and dose-dependent changes in phosphoinositide levels: the percentage of inositol monophosphate levels were decreased, whereas the percentage of inositol bisphosphate, inositol trisphosphate and inositol tetrakisphosphate levels were increased. The relative magnitude of the changes in phosphoinositide levels was similar to the changes in cytosolic calcium concentration. These results suggest that thrombin's mechanism of action on bone cells may involve increases in cytosolic calcium levels and in phosphoinositide metabolism.