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Notes: Abstract: β-Trace protein from pooled human CSF was purified to homogeneity. An apparent molecular mass of 23–29 kDa was determined for the polypeptide on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Amino-terminal sequencing of the polypeptide yielded the unique amino acid sequence APEAQVSVQPNFQQDKFLGRWFSA24. Alignment of amino acid sequences obtained from tryptic peptides with the sequence previously deduced from a cDNA clone isolated by other investigators allowed the identification of β-trace protein as prostaglandin D synthase [prostaglandin-H2 D-isomerase; (5Z, 13E)-(15S)-9α, 11 a-epidioxy-15-hydroxyprosta-5,13-dienoate D-isomerase; EC 5.3.99.2]. A conservative amino acid exchange (The instead of Ser) was detected at amino acid position 154 of the β-trace polypeptide chain in the corresponding tryptic peptide. The two N-glycosylation sites of the polypeptide were shown to be almost quantitatively occupied by carbohydrate. Carbohydrate compositional as well as methylation analysis indicated that Asn29and Asn56 bear exclusively complex-type oligosaccharide structures (partially sialylated with α2–3- and/or α2–6-linked N-acetylneuraminic acid) that are almost quantitatively α1-6 fucosylated at the proximal N-acetylglucosamine; ∼70% of these molecules contain a bisecting N-acetylglucosamine. Agalacto structures as well as those with a peripheral fucose are also present.

Notes: Abstract The effect of antidepressant and neuroleptic drugs on the electrically evoked release of serotonin (5-HT) was investigated in rat brain cortical slices preincubated with 0.1 μmol/l 3H-5-HT. Zimelidine, trazodone, clomipramine, doxepin, and viloxazine (1 μmol/l each) enhanced the electrically-induced 3H overflow by 20–44%. Six other antidepressants and five neuroleptics did not increase the evoked transmitter release. Only trazodone and viloxazine also increased the 3H overflow in experiments in which neuronal 5-HT reuptake was already blocked by 6-nitroquipazine. 5-HT and clonidine inhibited the electrically-induced 3H-5-HT release by stimulation of presynaptic 5-HT autoreceptors and α2-adrenoceptors, respectively; trazodone and viloxazine had no effect on the concentration-response curves of 5-HT and clonidine. Other psychotropic agents with well known antiserotonergic activities also failed to block presynaptic 5-HT autoreceptors. It is concluded that zimelidine, clomipramine, and doxepin enhanced the 3H-5-HT overflow by inhibition of neuronal 5-HT uptake, whereas the increase produced by trazodone and viloxazine cannot be explained by reuptake inhibition or interaction with presynaptic receptors.

Notes: Summary The influence of thyroid hormones on the concentration and properties of α1-adrenoceptors in a crude membrane fraction obtained from the rat cerebral cortex was investigated using the [3H]-WB 4101 binding assay. Animals were made hypothyroid by feeding 6-propyl-2-thiouracil for 8 weeks. Hyperthyroidism was induced by triiodothyronine injections (50 μg/100 g body weight) for 9 days. 1. The binding of [3H]-WB 4101 was saturable and of high affinity in controls as well as in hyper- and hypothyroid animals. The maximal number of binding sites (B max), which amounted to 95 fmol/mg protein in control animals, was increased by 27% in cortical membranes from hyperthyroid rats and reduced by 23% in the hypothyroid group. 2. The reduction in [3H]-WB 4101 binding due to 6-propyl-2-thiouracil feeding was reversible by triiodothyronine treatment. 3. Dissociation constants (K D) calculated from saturation experiments (0.25 nM) or kinetic data (0.21 nM) remained unchanged in altered thyroid states. 4. Inhibition of [3H]-WB 4101 binding by adrenergic agonists and antagonists revealed no differences between euthyroid and hypothyroid animals. The higher affinity of prazosin to the binding sites compared with yohimbine indicated that [3H]-WB 4101 predominantly labeled α1-adrenoceptors. It is concluded that thyroid hormones regulate the number of α1-adrenoceptors in membranes of the rat cerebral cortex, leaving their affinities unchanged.

Notes: Summary Cardiovascular alterations in hypo- and hyperthyroidism have been ascribed to changes of noradrenergic neurotransmission. In the present study the influence of thyroid hormones on adrenoceptors in the rat heart was further characterized. The effect of artificial hypothyroidism (induced by feeding 6-propyl-2-thiouracil, PTU) and hyperthyroidism (induced by daily injections of triiodothyronine, T3) on myocardial adrenoceptor binding, catecholamines, some physiological responses, and their interdependence was examined. 1. The density of myocardial β-adrenergic binding sites (3H-dihydroalprenolol, 3H-DHA) was reduced after PTU (by 38%) and enhanced after T3 treatment (by up to 82%). The increase was dose- and time-dependent and reversible within 4 days. No changes of the affinity of 3H-DHA to its binding sites were observed. Only L-T3 and L-T4 proved to be active, D-T3 and reverse T3 had no effect. The rise in β-adrenoceptor density caused by T3 was prevented by concomitant administration of cycloheximide, indicating its dependence on protein synthesis. 2. The density of myocardial α 1-adrenergic binding sites (3H-prazosin) was significantly reduced in the PTU group (by up to 28%) and even more distinctly by T3 treatment (by up to 50%). K D values remained unaltered. 3. The noradrenaline content and turnover of rat hearts was significantly reduced by T3-induced hyperthyroidism. PTU treatment had no influence on content and turnover of noradrenaline. Plasma noradrenaline as well as adrenaline levels in freely moving rats were increased by PTU treatment 9- and 5-fold, respectively. In T3-injected animals no significant changes were measured. 4. The density of adrenoceptors is known to be inversely correlated with catecholamine levels in several organs. Neither α- nor β-adrenoceptor changes in the myocardium of dysthyroid rats could be attributed to such a homologous regulation, since they still occurred after chemical sympathectomy with 6-hydroxydopamine and adrenalectomy. 5. Hypertrophy of the heart due to T3 could not be explained by prolonged β-adrenergic stimulation because it was not inhibited by 6-hydroxydopamine or high doses of propranolol. A T3-induced tachycardia was recorded in pithed and in intact rats. It was not reduced to normal levels by the β-adrenoceptor antagonist sotalol and, thus, was independent of sympathetic influence. Hypothyroid pithed rats displayed a marked bradycardia, whereas in intact hypothyroid animals a normal heart rate was measured at rest. Obviously, an enhanced availability of catecholamines which seems to reflect an increased release and/or a central nervous compensatory mechanism was responsible for the maintenance of the normal heart rate. 6. In pithed rats the β-adrenoceptor-mediated increase in heart rate was attenuated by PTU treatment. The isoprenaline dose-response curve was shifted to the right, the maximal response was reduced. After T3 injections, the sensitivity to isoprenaline was not affected, but the maximal heart rate that could be obtained was increased. These results are compatible with the β-adrenoceptor changes described above. It is concluded that cardiovascular signs of hypo- and hyperthyroidism can only be explained by a complex interaction of several factors. Beside the changes of adrenoceptor density and an altered sensitivity to noradrenaline, a central nervous regulation and subsequent changes of catecholamine release as well as effects independent of the sympathetic nervous system have to be considered.

Notes: Summary We used novel highly subtype-selective antagonists to study whether α1A- and/or α1B-adrenoceptors mediate the stimulation of inositol phosphate generation by noradrenaline in rat cerebral cortex. Phentolamine (10 μM) and prazosin (100 nM) completely abolished the stimulated inositol phosphate generation. The α1A-selective antagonists 5-methyl-urapidil (100 nM) and (+)− and (−)-niguldipine (10 nM) caused only weak inhibition or none at all although these concentrations occupied α1A-adrenoceptors almost completely. In contrast, pretreatment with the irreversible α1B-selective chloroethylclonidine reduced the noradrenaline-stimulated inositol phosphate generation by 76 ± 8%. These data demonstrate that α1B-adrenoceptors couple to inositol phosphate generation; the signal transduction system of α1A-adrenoceptors remains unclear.

Notes: Summary The effect of different neurolepitc drugs (levomepromazine, haloperidol, thioridazine, clozapine and sulpiride) on (−)-3H-noradrenaline uptake and release by parieto-occipital slices of the rat cerebral cortex was investigated. 1. All neuroleptic drugs tested increased the 3H-efflux from electrically stimulated cortical slices preincubated in (−)-3H-noradrenaline already at 1 μM, clozapine was the most potent compound followed by haloperidol, thioridazine, levomepromazine and sulpiride. The enhanced 3H-efflux due to field stimulation was found at concentrations, which did not increase the basal 3H-efflux. Only haloperidol raised the basal 3H-efflux at 1 μM. 2. All neuroleptic drugs failed to inhibit (−)-3H-noradrenaline (10−7M) accumulation by cortical slices at 1 μM. Sulpiride was inactive in concentrations up to 100 μM. Clozapine again proved to be most potent at 10–100 μM. 3. Clozapine was able to enhance the stimulated transmitter overflow when noradrenaline uptake was already blocked by cocaine thus indicating a different mode of action. 4. Clozapine and levomepromazine antagonized the presynaptic α-adrenergic effect of clonidine. 5. The antidepressant drug amitriptyline increased the transmitter efflux at the same concentrations and to a similar extent as neuroleptic agents. It is concluded that neuroleptics enhance the stimulation induced noradrenaline release mainly by acting on presynaptic α-adrenoceptors. The effect of clozapine, however, includes a noradrenaline uptake inhibition. These findings may explain the increased noradrenaline turnover produced by neuroleptic drugs and the weak antidepressant action of low potent neuroleptics as well.