β-Adrenoceptors in the extraorbital lacrimal gland of the Syrian hamster characterization with [125I]-iodopindolol and evidence of sexual dimorphism

Summary Saturation and competition experiments with the radiolabeled -adrenergic antagonist (–)-[¹²⁵I]-iodopindolol were used to characterize -adrenoceptor density (B_max) and receptor affinity in the extraorbital lacrimal gland of male and female Syrian hamsters. Specific binding to the receptor was saturable. Scatchard analysis of saturation isotherms revealed a single population of receptor sites. Male glands had a significantly higher B_max (38.9±5.0 vs. 23.3±2.1 fmole/mg protein, ¯x±SEM, p< 0.02) and receptor affinity (expressed in a lower dissociation constant K_d: 0.065±0.013 vs. 0.120±0.015 nM, p<0.02) than female glands. Binding of the radiolabeled ligand in competition with various adrenergic antagonists showed the receptor to be stereospecific and of the ₂-subtype.     

Chronic cobalt-induced epilepsy: Noradrenaline ionophoresis and adrenoceptor binding studies in the rat cerebral cortex

Summary Several studies indicate that brain noradrenaline (NA) depletion facilitates the occurrence of epileptogenic syndromes in various animal models. In cobalt-induced epilepsy in the rat, seizure activity is associated with a cortical NA denervation. In order to search for cortical adrenoceptor modifications, inonophoretic studies and adrenoceptor binding assays were performed. At the period of maximal seizure activity, there was a significant supersensitivity of cortical neurons to the ionophoretic application of NA. An increase in the density of-adrenoceptor binding sites was observed. No modification in ₁- and ₂-adrenoceptor binding sites was found. This suggests that in cobalt-induced epilepsy there is a denervation supersensitivity which rests on a selective involvement of-adrenoceptors.     

β-CIT SPECT demonstrates blockade of 5HT-uptake sites by citalopram in the human brain in vivo

Summary The cocaine analogue 2--carbomethoxy-3--(4-iodophenyl)-tropane (-CIT) is a potent ligand for both dopamine- and serotonin uptake sites which in its¹²³I labeled form can be used for single photon emission computerized tomography (SPECT). It was demonstrated previously by SPECT-studies in non-human primates that¹²³I--CIT binds to dopamine transporters in the striatum and to serotonin transporters in hypothalamus and midbrain. The aim of the present study was to compare¹²³I--CIT binding in the brain stem of normal controls and a group of subjects under treatment with the selective serotonin reuptake inhibitor (SSRI) citalopram.¹²³I--CIT- SPECT was performed in 12 depressed patients under 20 mg (n=5), 40 mg (n=6) and 60 mg (n=1) citalopram daily, in one untreated depressed patient and in 11 controls at regular time intervals up till 24 hours p.inj. A highly significant reduction of -CIT binding was found in an area including mesial thalamus, hypothalamus, midbrain and pons in patients under citalopram compared to controls (44.1 ± 14.4 vs. 82.3 ± 18.6 cpm's/mCi × kg body weight; specific binding 4 hrs p.inj.; p=0.0001). No differences were seen between the high and low dose group and no changes were found in the striatum.¹²³I--CIT binding in the brain stem and striatum in one untreated depressed patient fell within the range of control values.To our knowledge this is the first report directly demonstrating the effect of a selective serotonin uptake inhibitor in the brain in humans in vivo. SPECT measurements of serotonin uptake sites in patients with depression and other psychiatric disorders might provide better insights into the pathophysiology of these disorders and into mechanisms of drug action.     

Cytoplasmic and axoplasmic density variations in relation to hyperactivity

Summary The density of the cytoplasm and axoplasm of the anterior horn cell in rats was determined by X-ray microradiography. The average density of the cytoplasm of more than 400 cells from control rats was 0.31 g/³, while that of over 600 cells from rats fed IDPN (- iminodipropionitrile) was 0.43 g/³.Hyperactivity developed during the first 5 weeks and was associated with a gradual increase in cytoplasmic density to 0.51 g/³.At 6 weeks there was a drop in density to 0.36 g/³ which coincided with the appearance of axonal balloons having a density of 0.17 g/³.During the 7–12th week on the diet, the cytoplasmic density showed a gradual increase to 0.59 g/³ and the balloons to 0.29 g/³.The volume of the nerve cells remained fairly constant. The density increases were discussed in relation to hypertrophy, dystrophy, and hyperactivity.

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Zusammenfassung Die Dichte des Cytoplasmas und Axoplasmas der Vorderhornzellen von Ratten wurde durch Röntgenmikroradiographie bestimmt. Die mittlere Dichte des Cytoplasmas von mehr als 400 Zellen der Kontrollratten war 0,31 g/³, während die mittlere Dichte von mehr als 600 Zellen der Ratten, die mit IDPN (- iminodipropionitrile) gefüttert waren, 0,43 g/³ war.Hyperaktivität entwickelte sich während der ersten 5 Wochen und war mit einer progressiven Zunahme der Cytoplasmadichte bis auf 0,51 g/³ verbunden.Nach 6 Wochen sank die Dichte auf 0,36 g/³. Diese Tatsache traf mit dem Auftreten der Axonauftreibungen zusammen, die eine Dichte von 0,17 g/³ hatten.Nach 7–12 Wochen zeigte die Cytoplasmadichte eine progressive Zunahme auf 0,59 g/³ und die der Auftreibungen eine Zunahme auf 0,29 g/³.Das Volumen der Nervenzellen blieb ziemlich konstant.Die möglichen Zusammenhänge zwischen Zunahme der Dichte, Hypertrophie, Dystrophie und Hyperaktivität werden dargestellt.

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Supported by U. S. Public Health Grant NB 1305.     

Alterations in cerebral glutamic acid decarboxylase and3H-flunitrazepam binding during continuous treatment of rats for up to 1 year with haloperidol,sulpiride or clozapine

Summary Rats were treated continuously for 12 months with therapeutically equivalent doses of haloperidol (1.4–1.6 mg/kg/day), sulpiride (102–109 mg/kg/day) or clozapine (24–27 mg/kg/day) and examined for alterations in brain glutamic acid decarboxylase (GAD) and³H-flunitrazepam binding.Administration of haloperidol, but not sulpiride or clozapine, for 6 or 12 months increased striatal GAD activity. None of the drug treatments altered nigral GAD activity when examined after 1, 3, 6, 9 or 12 months administration.The number of specific³H-flunitrazepam binding sites (B_max) in striatal membrane preparations were not altered by 12 months administration of haloperidol, sulpiride or clozapine. Surprisingly, B_max for³H-flunitrazepam binding to cerebellar membrane preparations was decreased-by 12 months administration of all drug treatments. The dissociation constant (Kd) for³H-flunitrazepam binding in striatal and cerebellar preparations was not altered. The ability of GABA (0.25–100 M) alone, and in conjunction with sodium chloride (200 mM), to stimulate specific³H-flunitrazepam binding in striatal and cerebellar preparations was unaltered by haloperidol, sulpiride or clozapine administration for 12 months. The selective effect of haloperidol, but not sulpiride or clozapine, treatment on striatal GAD activity parallels the ability of haloperidol, but not sulpiride or clozapine, to induce striatal dopamine receptor supersensitivity in the same animals. The actions of haloperidol may reflect its greater ability to induce tardive dyskinesia compared to sulpiride or clozapine.     

Interval training in elderly men increases both heart rate variability and baroreflex activity

Abstract Aims Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health. Methods We assessed maximal oxygen consumption (VO_2max), auto- nomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in eleven elderly men (73.5±4.2 years) before and after a 14-week program of intensive cycloergometer interval training. The standard HRV indices were calculated using time domain (mean RR, PNN50, RMSSD, SDNN, SDANN and SDNNIDX), and Fourier transform (total power, ULF,VLF, LF, LFnu, HF, HFnu and LF/HF) analyses of 24-hour, daytime and nighttime Holter recordings. The SBR was calculated from 15-minute recordings of spontaneous blood pressure and RR interval variations using the sequence (slope, slSBR) and cross-spectral (SBR_HF and SBR_LF) methods. Results After the training period,VO_2max increased by 18.6 % (26.8±4.4 to 31.8±5.2 ml · kg^–1 · min^–1, p<0.01). The nocturnal parasympathetic indices of HRV increased (PNN50: 3.05±2.21 to 5.00±2.87%, RMSSD: 29.1±7.6 to 38.8±10.9 ms, HF: 117±54 to 194±116 ms²/Hz, all p<0.05) as did the SBR indices (slSBR: 7.0±1.8 to 9.8±2.1 ms·mmHg^–1, p<0.01; SBR_HF: 6.9±2.2 to 10.5±3.7 ms ·mmHg^–1, p<0.05; SBR_LF: 5.3±2.3 to 6.9±3.1 ms ·mmHg^–1, p=0.22). Conclusion Intensive endurance training in elderly men enhanced parasympathetic parameters of HRV and, interestingly, of SBR. Physiological mechanisms and long-term clinical effects on health status should be further investigated.     

A simplified radioimmunological method for the determination of human β-endorphin in cerebrospinal fluid

Summary Human -endorphin-like immunoreactive substances ( _h -EI) in human cerebrospinal fluid (CSF) were determined radioimmunologically. The cross reactivity of the antibodies to human -endorphin ( _h -E) amounted to 40% for human -lipotropin ( _h -LPH) whilst it was less than 1% for leu-and metenkephalin, - and -endorphin, fraction I and II [5], substance P and -MSH. Prior to radioimmunological determination, an adsorbtion of _h -EI from CSF with silicic acid was carried out and followed by a desorbtion, using a mixture of aceton/hydrochloric acid. This method was chosen because the ratio of _h -LPH to _h -E in the desorbat can be shifted in favour of _h -E owing to the variation in recoveries r ( =33%, =64%). On the one hand, this enables a more specific determination of _h -E and, on the other hand, and separation of any peptidase than may be present [9]. An adsorbtion/desorbtion of 2 ml CSF suffices to prove the presence of 20–150 pg/ml (6–48 fmol/ml) of _h -EI.The CSF of 28 patients with various neurological diseases was examined and 24 of them had concentrations of 20–70 pg/ml _h -EI. The remaining four, which had concentrations less than 20 pg/ml, came from meningitis patients undergoing corticoid therapy.A purchasable RIA kit was tested for its determination of _h -E and was found to be unsuitable.

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Zusammenfassung Beta-human-Endorphin-like immunreaktive Substanzen ( _h -EI) im menschlichen Liquor (CSF) wurden radioimmunologisch bestimmt. Die Kreuzreaktivität des von uns eingesetzten Antikörpers gegen Beta-human-Endorphin ( _h -E) zum Beta-human-Lipoprotein ( _h -LPH) betrug 40%, während sie zu Leu- und Met-Enkephalin, Alpha- und Gamma-Endorphin, Fraktion I und II nach Terenius [10], Substanz P und Alpha-MSH geringer war als 1%. Vor der radioimmunologischen Bestimmung wurde eine Adsorption von _h -EI aus CSF an Kieselsäure mit anschließender Desorption mittels eines Gemisches aus Aceton/Salzsäure durchgeführt. Diese Methode wurde gewählt, weil sich dadurch das Verhältnis von _h -LPH zu _h -E im Desorbat zugunsten von _h -E aufgrund der unterschiedlichen Recoveries R ( =33%, =66%) verschob. Damit wird einerseits eine erhöhte Spezifität bei der Bestimmung von _h -EI und andererseits eine Abtrennung von eventuell vorhandenen Peptidasen erreicht. Eine Adsorption/Desorption aus 2 ml CSF genügt, um _h -EI von 20–150 pg/ml (6–48 fmol/ml) nachzuweisen.Patienten (n=28) mit verschiedenen neurologischen Erkrankungen wiesen Werte von 20–70 pg/ml auf. Vier Liquores unter 20 pg/ml stammten von Meningitis-Patienten, welche unter einer Corticoidtherapie standen.Ein käuflicher RIA-Kit wurde auf seine Eignung zur Bestimmung von _h -E untersucht und verworfen.

     

Autoradiographic characterization of [3H]inositol (1,4,5) trisphosphate and [3H]inositol (1,3,4,5) tetrakisphosphate binding sites in human brain

Summary Autoradiographic techniques were used to investigate the characteristics of tritiated inositol(1,4,5)trisphosphate ([³H]IP₃) and inositol (1,3,4,5)tetrakisphosphate ([³H]IP₄) binding to human brain. In brain sections [³H]IP₃ exhibited a two-site binding with K _d values of 87 nM and 9.3 M respectively for the higher and lower affinity sites. [³H]IP₄ also bound to two sites with K _d values of 43 nM and 1.4 M, respectively. With the conditions fixed in this study, [³H]IP₃ and [³H]IP₄ autoradiography in the cortex, caudate, hippocampus and cerebellum were performed. The most prominent [³H]IP₃ binding among these regions was found in the cerebellum, particularly in the molecular layer. Within the hippocampus, the subiculum and the CA1 region showed much more prominent binding than the other subfields. [³H]IP₄ binding was fairly homogeneous in the regions studied, with the exception of a slightly higher binding in the molecular layer of the cerebellum.     

GABA and its neural regulation in rat brown adipose tissue

Summary By using a radioreceptor assay GABA was detectable in rat interscapular brown adipose tissue (IBAT), the levels being 1% those of CNS and 10-fold those of peripheral plasma. Injection of the glutamic acid decarboxylase (GAD) inhibitor 3-mercaptopropionic acid lowered IBAT GABA levels by about half while injection of the GABA transaminase inhibitor -acetylenic GABA increased them by 230%. Rats kept at 4C for 14 days exhibited IBAT GABA levels that were about half those found at 22C. Accumulation of IBAT GABA after -acetylenic GABA increased by 2-fold in cold-exposed rats. Sympathetic denervation of IBAT prevented the effect of the cold environment on GABA content and impaired that on GABA accumulation. GAD activity was detectable in IBAT homogenates and isolated brown adipocytes. Exposure of rats to cold increased V_max of GAD without modifying its Km, regardless of intactness of innervation. In binding studies with³H-GABA as a ligand, two types of sites were uncovered of K_D=14 and 146 nM, respectively. In the presence of 2.5 mM Ca²⁺ bicuculline and baclofen were 57 and 46% as effective as GABA to displace³H-GABA from IBAT binding sites. The results indicate existence, possible synthesis and type A and B receptors of GABA in rat IBAT.     

Effects of dopamine D-1 and D-2 antagonists on decision making by rats: No reversal of neuroleptic-induced attenuation by scopolamine

Summary The presynaptic actions of the potassium channel blocker Dendrotoxin (DTX) on the Ca⁺²-dependent release of endogenous glutamate (GLU) and aspartate (ASP) have been tested in synaptosome-enriched preparations from rat striatum.24 hours after the intrastriatal administration of DTX the K⁺-evoked release of GLU and ASP from the striatal synaptosomes was decreased by 40–45%. No changes in the total synaptosomal content of the amino acids were observed. Superfusion of immobilized synaptosomes with DTX or 4-aminopyridine resulted in a dose-dependent increase in the basal outflow of GLU and ASP. The release of GLU stimulated by DTX was Ca⁺²-dependent and was not abolished by supervising the synaptosomes with 50 M D-ASP. Moreover, continous superfusion of DTX (7 M) to synaptosomes almost completely dumped the subsequent release of GLU and ASP stimulated by 20mM K⁺. It is concluded that blockade of presyanptic K⁺ channels by DTX leads to a massive release of the transmitter pool of GLU (and possible also ASP) from isolated nerve terminals and to a depletion of the amino acid releasable pool.     

Orphenadrine is an uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist: binding and patch clamp studies

Summary Orphenadrine has been used as an antiparkinsonian, antispastic and analgesic drug for many years. Here we show that orphenadrine inhibits [³H]MK-801 binding to the phencyclidine (PCP) binding site of the N-methyl-D-aspartate (NMDA)-receptor in homogenates of postmortem human frontal cortex with a K_i-value of 6.0 ± 0.7 M. The NMDA receptor antagonistic effects of orphenadrine were assessed using concentration- and patch-clamp techniques on cultured superior colliculus neurones. Orphenadrine blocked open NMDA receptor channels with fast kinetics and in a strongly voltage-dependent manner. The IC₅₀-value against steady state currents at –70mV was 16.2 ± 1.6 M (n=6). Orphenadrine exhibited relatively fast, concentration-dependent open channel blocking kinetics (K_on 0.013 ± 0.002 10⁶M^–1S^–1) whereas the offset rate was concentration-independent (K_off 0.230 ± 0.004 S^–1). Calculation of the ratio K_off/K_on revealed an apparent K_d-value of 17.2 M which is nearly identical to the IC₅₀ calculated at equilibrium.     

Alpha-1 and alpha-2 adrenoceptor binding in cerebral cortex: Competition studies with [3H]prazosin and [3H]idazoxan

Summary The tritiated adrenergic antagonists prazosin ([³H]PRZ) and idazoxan ([³H]IDA, or RX-781094) bind specifically and with high affinity in membrane preparations from cerebral cortex to alpha-1- and alpha-2-adrenoceptors respectively. Saturation experiments, performed to determine the density of receptors (B_max; maximum binding capacity) and the dissociation constant (K_d 25 °C), were analyzed by the methods of Eadie and Hofstee, iterative modelling, and the procedure of Hill. The pharmacologic properties and specificity of the labelling was verified by displacement experiments using alpha-adrenergic antagonists and agonists. The antagonist drugs showed the following order of potency to displace [³H]prazosin: prazosin phentolamine corynanthine > pyrextramine yohimbine piperoxan > benextramine > idazoxan; for the agonists: clonidine (–)-noradrenaline (–)-adrenaline phenylephrine, while other drugs, such as (–)-propranolol, dopamine, (–)-isoproterenol and serotonin only competed with the alpha-1-ligand at concentrations above 20 M. The alpha₂-sites labelled by [³H]idazoxan were characterized by the antagonist displacement sequence idazoxan phentolamine > yohimbine = > piperoxan pyrextramine benextramine prazosin corynanthine. The agonists order of potency to compete with [³H]idazoxan was clonidine phenylephrine = > (–)-adrenaline > (–)-noradrenaline, and for other related drugs it was (–)-propranolol dopamine serotonin > (–)-isoproterenol. These competition experiments clearly showed two pharmacologically distinct sites, but question the relative specificity of some of the adrenergic drugs.Abreviations [³H]PRZ [³H]prazosin - [³H]IDA [³H]idazoxan - B_max maximum binding capacity - K_d dissociation constant - IC 50 inhibitory concentration that reduces binding by 50% - K_i inhibition-dissociation constant - nH Hill coefficient - CMC coefficient of multiple correlation - fmol/mg p fentomoles per mg of protein - nM nanomolar Recipient of a F.R.S.Q. Studentship.     

Effect of 1-methyl-4-phenylpyridinium (MPP+) on mitochondrial membrane potential in cerebellar neurons: Interaction with the NMDA receptor

Summary The effect of MPP⁺, a dopaminergic neurotoxin, in mitochondrial membrane potential was investigated in dissociated cerebellar granule cells using rhodamine 123 and flow cytometry. MPP⁺ (1 mM) decreased the mitochondrial membrane potential by 30%. Antagonists of the NMDA receptor complex, such as MK-801 (IC₅₀ value of 20.92 ± 0.02 nM), 5,7-dichlorokynurenic acid (IC₅₀ value of 6.46 ± 1.06 M) and D-AP5 (IC₅₀ value of 8.29 ± 0.63 M), inhibited the action of MPP⁺. Neither NBQX, nor riluzole, nor desipramine modified the action of MPP⁺. Dibucaine restored the basal values of mitochondrial membrane potential altered by MPP⁺. Since, in the presence of NMDA, MPP⁺ antagonized the effect of this total agonist, it can be concluded that, in this preparation, MPP⁺ interacts with the NMDA receptor complex as a partial agonist. This interaction could be the result of an allosteric modulation of the NMDA receptor complex by MPP⁺. The decrease of mitochondrial membrane potential induced by MPP⁺ is antagonized by dibucaine, suggesting that this effect is mediated by an activation of phospholipase A₂.     

Postmortem- and cryostability of the potassium-evoked release of [3H]5-hydroxytryptamine from rat cerebral cortical miniprisms

Summary A prerequisite for the study of neurotransmitter release from human brain autopsy samples with histories of different diseases is that the cryo- and postmortem stability of the release process is good. In the present study, the effect of post-mortem delay and of storage at –70 °C by the slow freeze — fast thaw method of Hardy et al. [J Neurochem (1983) 40: 608–614] (which allows for the retention of metabolic activity of the tissue after the storage and thawing) of rat cerebral cortex samples upon the release of [³H]5-hydroxytryptamine ([³H]5-HT) from prelabelled miniprisms has been investigated. Storage of samples at –70 °C by this method resulted in samples that accumulated less [³H]5-HT but showed an increased sensitivity to the Ca²⁺-dependent releasing properties of K⁺ when compared with fresh samples. On the other hand, the sensitivity of the K⁺-evoked release to the inhibitory effects of the serotoninergic agonist 5-methoxy-N,N-dimethyltryptamine were reduced by storage. The effects on [³H]5-HT accumulation and on K⁺-evoked release were due mainly to the freeze-thaw procedure, the length of storage at –70 °C having only a minor influence on these parameters. A post-mortem interval of 5 hours at either +4 or +22°C prior to storage of the tissue reduced the K⁺-evoked release of tritium, but did not affect the accumulation of [³H]5-HT or the inhibitory effects of 5-methoxy-N,N-dimethyltryptamine on the K⁺-evoked release over and above the effects produced by the storageper se.     

Apolipoprotein E co-localizes with newly formed amyloid β-protein (Aβ) deposits lacking immunoreactivity against N-terminal epitopes of Aβ in a genotype-dependent manner

Different types of amyloid -protein (A)-containing plaques occur in brains of Alzheimers disease (AD) patients. Diffuse plaques seen during early stages of AD differ from neuritic plaques in later stages both with respect to the length of the A peptides and the presence of other proteins, e.g., apolipoprotein-E (apoE). Since apoE is involved in A transport and clearance, and the 4-allele of the apolipoprotein-E gene (APOE) is a major risk factor for sporadic AD, it is plausible to speculate that apoE plays a pathophysiological role in the initiation of A deposition. To address the issue of whether binding of apoE to A is involved in initial A deposition, we studied the human medial temporal lobe of 60 autopsy cases encompassing the full spectrum of AD-related pathology. In temporal lobe regions, which become involved for the first time at a given stage of -amyloidosis, all plaques represent newly formed plaques, and these were studied with immunohistochemical methods. ApoE was present in 36 cases, and was frequently co-localized with newly formed A deposits detectable with anti-A₄₂ but not with antibodies raised against N-terminal epitopes of A. In 10 additional cases, immunoreactivity against apoE was completely lacking in newly formed plaques, which, at the same time, displayed immunoreactivity against N-terminal epitopes of A. The failure of N-terminal epitopes of A to co-localize with apoE in newly formed plaques indicates that these deposits presumably contain apoE-A complexes, in which the N-terminal epitopes of A are often concealed after complexing with apoE, thus preventing subsequent binding of antibodies. Moreover, apoE-positive newly formed plaques were seen more frequently in APOE 4/4 cases than in non-APOE 4/4 individuals, thereby underlining the potentially crucial role of apoE for the development of A deposits.     

β-Carbolines as selective monoamine oxidase inhibitors:In vivo implications

Summary The inhibitory action of a range of-carbolines on human and rat monoamine oxidase (MAO) A and B has been studied. Concentrations of 5-hydroxytryptamine and phenylethylamine, approximately at their K_m values, were used as substrates for MAO A and B respectively. A wide variation in selectivity was found, with harmaline being 10,000 times more potent an inhibitor of A than B whereas, using tetrahydro--carboline and harmane, the difference was nearer to ten-fold. Of the carbolines which have been found endogenously, tetrahydro--carboline, 6-methoxytetrahydro--carboline and harmane are all sufficiently potent inhibitors of human MAO A, with I₅₀ values of 5×10^–6, 10^–6, 5×10^–7M respectively, for this property to be of possible physiological significance. Harmane, with an I₅₀ of 5×10^–6M, might also play a role as an inhibitor of MAO B.     

Personality characteristics,environmental factors and glycemic control in adolescents with diabetes

Metabolic control in adolescents with diabetes is difficult to achieve and seems to depend in part on personality and the family environment. We tried to identify relevant characteristics in this study. We administered the Children's Manifest Anxiety Scale, a Self-Competence scale, a Locus of Control Scale, and a structured interview, to 40 adolescent diabetics and 39 healthy controls, and the Rotter Locus of Control Scale to mothers. There were indications of more depressive thoughts and feelings (P=0.036) and slightly more anxiety (P=0.065) in the diabetics than in the controls. The diabetics who put in more effort at school had better metabolic control. Also, the diabetics who worried about their illness (P=0.021) and the ones who belonged to lower social class (P=0.011) had poorer metabolic control than others. The diabetics did not differ in locus of control and self-competence from controls. Locus of control, self-competence and anxiety were not correlated to HbA_1c values.

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Zusammenfassung Eine gute Einstellung eines Jugendlichen-Diabetes ist schwer zu erreichen und scheint zum Teil von der betreffenden Persönlichkeit und dem familiären Umfeld abzuhängen. Wir haben versucht, relevante Merkmale in dieser Studie zu identifizieren. Wir wandten die Children's Manifest Anxiety Scale, eine Selbstkompetenz Skala, eine Skala zur Feststellung von Kontrollüberzeugungen und ein strukturiertes Interview an, um 40 jungendliche Diabetiker und 39 gesunde Kontrollen zu untersuchen, außerdem die Rotter Locus of Control Scale für die Untersuchung der Mütter. Es fanden sich Hinweise auf mehr depressive Gedanken und Gefühle (p=0,036) und leicht erhöhte Angstskalen (p=0,065) bei den Diabetikern im Vergleich zu den Kontrollen. Die Diabetiker, die sich in der Schule stärker bemühten, hatten eine bessere Einstellung. Ferner zeigten die Diabetiker, die sich aufgrund ihrer Erkrankung Sorgen machten (p=0,021), ebenso wie die, die einer niedrigeren sozialen Schicht angehörten, eine schlechtere Einstellung. Die Diabetiker unterschieden sich nicht von Kontrollen im Hinblick auf ihre Kontrollüberzeugung und Selbstkompetenz. Kontrollüberzeugung, Selbstkompetenz und Angst korrelierten nicht mit den HbA_1c-Werten.

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Résumé L'équilibre métabolique des adolescents diabétiques est difficile à obtenir et dépend en partie de la personnalité et de l'environnement familial. Nous avons essayé dans cette étude d'identifier les caractéristiques significatives. Nous avons administré l'échelle d'anxiété manifeste des enfants, une échelle d'auto-compétence, une échelle de contrôle et un entretien structuré à 40 adolescents diabétiques et à 39 témoins-contrôles sains et l'échelle Rother de point de contrôle aux mères. Il y avait des indications en faveur de plus de sentiments et de pensées dépressives (p=0.036) et légèrement plus d'anxiété (p=0.065) chez les diabétiques que chez les sujets contrôles. Les diabétiques qui fournissaient plus d'efforts à l'école avait un meilleur équilibre métabolique. Egalement les diabétiques préoccupés par leur maladie (p=0.021) et ceux qui appartenaient à des classes sociales inférieures (p=0.0011) avaient un contrôle métabolique moins bon que les autres. Les diabétiques ne différaient pas dans le point de contrôle de l'auto-compétence des cas témoins. Les points de contrôle, l'auto-compétence et l'anxiété n'étaient pas corrélés aux valeurs HbA_1c.

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This paper was partly presented at the 6th International Congress of Psychiatry. Athens, October 1989.     

Neurochemical evidence for a neuronal GABAergic system in the rat sympathetic superior cervical ganglion

Summary Some characteristics of gamma aminobutyric acid (GABA) uptake and release in rat superior cervical ganglion (SCG) were investigated. Kinetic analysis of GABA uptake indicated the existence of both high affinity (Km=18.6 M) and low affinity (Km=485 M) uptake systems.³H-GABA influx was decreased by inhibitors of glial (-alanine), neuronal (2,4-diaminobutyric acid, DABA), or glial and neuronal GABA uptake (nipecotic acid).³H-GABA efflux was elicited by K⁺ depolarization in a dose-dependent manner, an effect unaltered by severing the preganglionic nerve fibers. Superfusion of SCG expiants with DABA or -alanine resulted in increased³H-GABA efflux from tissue, an effect amplified by the absence of calcium in the superfusion medium.³H-GABA loading in the presence of DABA, but not in the presence of -alanine, resulted in abolition of K⁺-elicited³H release. At 20 mM, but not at 50 mM K⁺, the release of³H-GABA was inhibited by replacing Ca²⁺ by Mg²⁺ and by adding EGTA, or by incubating SCG in the presence of the Ca²⁺-channel blocker verapamil. Veratrine evoked GABA release in a Ca²⁺-independent manner. None of several putative SCG autacoids or agonists (nicotine, muscarine, norepinephrine, dopamine, serotonin, baclofen, muscimol) significantly modified GABA release.     

A carrier for GABA uptake exists on noradrenaline nerve endings in selective rat brain areas but not on serotonin terminals

Summary -Aminobutyric acid (GABA) increased in a concentration-dependent way (3–300M) the basal release of tritium from rat cerebral cortex and hippocampus synaptosomes, prelabelled with³H-noradrenaline (³H-NA); however, GABA was ineffective on hypothalamic nerve endings. The effect displayed by low concentrations (<10M) of GABA was largely bicuculline-sensitive. Muscimol mimicked GABA, while (–)baclofen was inactive.The releasing effects produced by concentrations of GABA higher than 10M were largely prevented by SK&F89976A, SK&F 100330A and SK&F 100561, three novel GABA uptake inhibitors. When present together, GABA uptake blocker and bicuculline counteracted entirely the GABA effects. The basal release of³H-5-hydroxytryptamine (³H-5-HT) in synaptosomes from various CNS regions was not affected by GABA. In conclusion: GABA can enhance³H-NA release not only through GABA-A receptors but also by penetrating into NA terminals through a GABA uptake system. This implies coexistence of carriers for NA and GABA uptake on a same nerve terminal. The carrier coexistence occurs in selective CNS areas. The phenomenon appears to be transmitter-selective.     

Electron microscope studies of Schwann cells during the Wallerian degeneration with special reference to the cytoplasmic filaments

Summary The fine structure of Schwann cells of the sciatic nerve of adult rabbits during the several phases of Wallerian degeneration was studied. For electron microscopy buffered osmium tetroxide, Vestopal W and the lead and uranyl staining was used As a result of the axon degeneration, the Schwann cells are activated and the myelin sheaths break down. During the phase of intraplasmatic digestion of the myelin, the ribosomes increase considerably and the ER swells. Afterwards a conspicuous granular thickening of the ground plasm is to be noted (stage of dark cells). The granular ground plasm forms into filaments, which stand out clearly before the light background as tender strings about 60–80 Å in thickness (stage of light cells). During this stage, the ribosomes have disappeared almost completely and the ER has collapsed. The Schwann cell has entered into its stage of rest which is characterized by a high amount of plasmatic filaments. Schwann cell filaments differ from so-called neurofilaments in respect of their genesis and their ultrastructure. In conclusion, the differences in genesis and morphology between the two filamentous structures are discussed.

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Zusammenfassung Elektronenoptisch wurden die verschiedenen Phasen untersucht, die Schwannsche Zellen während der Wallerschen Degeneration durchlaufen. Als Untersuchungsmaterial dienten der N. ischiadicus des erwachsenen Kaninchens. Für die Elektronenmikroskopie wurden Osmium-tetroxyd, Vestopal W sowie die Bleiund Uranylkontrastierung verwendet.Als Folge der Axondegeneration werden die Schwannschen Zellen aktiviert und die Markscheiden fragmentiert. In der Phase des intraplasmatischen Myelinabbaus findet eine hochgradige Vermehrung der Ribosomen und eine Schwellung des endoplasmatischen Reticulums statt. Danach tritt eine starke granuläre Verdichtung des Grundplasmas in Erscheinung (Phase der dunklen Zellen). Aus dem granulären Grundplasma formieren sich anschließend die Filamente, die sich vor dem hellen Untergrund als zarte, etwa 60–80 Å dicke Fäden abzeichnen (Stadium der hellen Zellen). In diesem Stadium sind die Ribosomen bis auf kleine Reste verschwunden, und das ER ist abgeschwollen. Die Schwannsche Zelle hat ihr Ruhestadium eingenommen, das durch eine starke Anhäufung der Plasmafilamente charakterisiert ist. Die Schwannschen Zellfilamente unterscheiden sich von sogenannten Neurofilamenten in bezug auf die Genese und die Feinstruktur. Abschließend werden die Unterscheidungsmerkmale in der Genese und der Morphologie beider filamentärer Strukturen diskutiert.

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Supported by the Deutsche Forschungsgemeinschaft.