Activation of dopamine D1 receptors or α1 adrenoceptors is not involved in the EEG effect of nicotine in rats

Based on previous own EEG-studies and behavioural studies of other authors, it has been claimed recently that D₁ receptors are involved in addictive properties of drugs. It seemed, therefore, of interest to study whether nicotine produces D₁-characteristic EEG alterations in rats. EEG was recorded in non-anesthetized, freely moving rats, transmitted telemetrically and underwent power spectral analysis.Nicotine (0.1, 0.2, 0.4 mg/kg s.c.) produced a desynchronization in the EEG and a decrease of power in all of the frequency bands (h577066/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">, h577066/xxlarge920.gif" alt="THgr" align="BASELINE" BORDER="0">, h577066/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">₁, h577066/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">₂, h577066/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁) except in h577066/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₂. With regard to behaviour, an increase of locomotor activity and some discontinuous sniffing was manifest. The effect of nicotine (0.2 mg/kg) was not antagonized by blockade of dopamine D₁ receptors by SCH 23390 (0.1 mg/kg s.c., 30 min before nicotine), although this drug by itself increased the power in most of the frequency bands. Prazosine (0.2 mg/kg i.p.), a selective antagonist at h577066/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">₁ adrenoceptors, by itself increased the power in all of the frequency bands, but also failed to antagonize the effects of nicotine (0.2 mg/kg). In contrast, the blocker of nicotinic cholinoceptors mecamylamine (1 mg/kg i.p.) was effective in antagonizing the action of nicotine on the EEG.The results suggest that in nicotine-mediated desynchronization and decrease of power in the EEG, the activation of dopamine D₁ or h577066/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">₁ adrenoceptors is not involved. Correspondence to: K. Kuschinsky at the above address     

Effect of ω-conotoxin on cholinergic and tachykininergic excitatory neurotransmission to the circular muscle of the guinea-pig colon

The aim of this study was to compare the stimulus-response characteristics of the cholinergic and tachykininergic excitatory transmission to the circular muscle of the guinea-pig proximal colon and their susceptibility to inhibition by the N-type calcium channel blocker h2j56815/xxlarge969.gif" alt="ohgr" align="BASELINE" BORDER="0">-conotoxin (CTX). All experiments were performed in the presence of guanethidine (3 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M), indomethacin (10 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M), L-nitroarginine (L-NOARG, 30 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M) and apamin (0.1 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M). In the presence of the tachykinin receptor antagonists, FK 888 (10 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M) and GR 94800 (3 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M), to block NK₁ and NK₂ receptors, respectively, electrical field stimulation (EFS) produced frequency-dependent atropine- (1 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M) sensitive contractions. In the presence of atropine (1 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M), EFS produced tachykininergic contractions which were abolished by the combined administration of FK 888 (10 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M) and GR 94 800 (3 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M). The maximal responses produced by cholinergic and tachykininergic neurotransmission ranged between 80 and 100% of the maximal contractile response to 80 mM KCI. The frequency of stimulation, pulse width and voltage required to produce 50% of the maximal cholinergic and tachykininergic contraction were not different from each other, although cholinergic transmission appeared more efficient in producing twitch contractions in response to single pulse EFS. Furthermore, cholinergic transmission was more efficient than tachykininergic transmission in producing contraction in response to short periods of EFS.CTX (0.1 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M for 30 min) produced a large and comparable rightward shift of the cholinergic and tachykininergic frequency-response curve (19 and 17 fold increase in the frequency of stimulation producing 50% of the maximal response, respectively) and markedly depressed (51 and 43% inhibition, respectively) the maximal concentrations response. CTX failed to affect the contraction of the colon produced by submaximally effective concentrations of the muscarinic receptor agonist, methacholine (0.1–0.3 h2j56815/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M) and those produced by the tachykinin NK₁ and NK₂ receptor selective agonists [Sar⁹] substance P sulfone and [\Ala⁸] neurokinin A (4–10) (1–3 nM).The present findings demonstrate that the cholinergic and tachykininergic components of the excitatory transmission to the circular muscle of the guinea-pig colon are activated at comparable intensities of nerve stimulation and are both inhibited, in a qualitatively and quantitatively comparable manner, by CTX at the prejunctional level. These findings are consistent with the idea that acetylcholine and tachykinins are co-released from the same population of enteric motoneurones which innervate the circular muscle of the colon. Correspondence to: C. A. Maggi at the above address     

Up-regulation of β1-adrenergic receptors in rat brain after chronic citalopram and fluoxetine treatments

Quantitative receptor autoradiography was used to study the effects of the selective serotonin reuptake inhibitors citalopram and fluoxetine and the tricyclic antidepressant imipramine on the regulation of h7575110n/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-adrenergic receptors in the rat brain. Rats were treated with saline, citalopram (10 mg kg^–1), fluoxetine (10 mg kg^–1), or imipramine (15 mg kg^–1) SC once daily for 14 days. [¹²⁵I]Iodocyanopindolol binding to h7575110n/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-adrenergic receptors was found to increase significantly in the caudate-putamen and the somatosensory areas of the frontal cortex after both citalopram and fluoxetine treatments. Imipramine treatment elicited a marked decrease in h7575110n/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁ binding in the outer laminae of the cingulate cortex, as well as in the motor and somatosensory areas of the frontal cortex. In a separate experiment, rats were treated with saline, citalopram (2.5, 10 and 20 mg kg^–1) or fluoxetine (2.5, 10 and 20 mg kg^–1) SC once daily for 14 days. The effects of citalopram and fluoxetine on h7575110n/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁ receptors in the somatosensory cortex and caudate-putamen were replicated. These results demonstrate that chronic administration of selective serotonin reuptake inhibitors, in contrast to imipramine, can cause a regional up-regulation of h7575110n/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-adrenergic receptors in the rat brain.     

A Simple and Rapid Fluorometric Determination Method of α1-Acid Glycoprotein in Serum Using Quinaldine Red

We examined different fluorescent probes suitable for fluorometric determination of h1x15w76v738/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">₁-acid glycoprotein (AGP) in serum. Quinaldine red (QR) was shown to bind strongly and selectively to AGP. Taking advantage of the enhanced fluorescence of QR in the presence of AGP, we developed a direct method for the determination of serum AGP without removal of other serum proteins such as albumin. AGP concentrations in serum of healthy volunteers and patients correlated well with results from the conventional single radial immunodiffusion (SRID) method (r = 0.93, slope = 1). The newly developed method is faster and has a larger analytical concentration range than the SRID method. This method can also be used to determine AGP in serum of experimental animals, and it can serve to monitor AGP serum concentrations for pharmacokinetic evaluation of basic drugs.     

Response of multicellular tumor spheroids to liposomes containing TNF-α

Summary This publication describes a new model to investigate the influence of tumor necrosis factor-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> (TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">) on a three-dimensional glial cell aggregate under defined, standardized, reproducible conditions using the glioma cell line A 172.The cells are initially grown as normal monolayer culture until they reach a cell density of up to 1×10⁶. Subsequently they are grown as spheroids by the liquid overlay technique. Spheroids grown in this way were divided into ten groups of more than 50 cell aggregates. Three groups were coincubated with free TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> in increasing dosages (100 ng/ml, 200 ng/ml and 1000 ng/ml); three groups were incubated with empty liposomes (0.2 mg/ml, 0.4 mg/ml and 2 mg/ml); three groups received liposomes which had been loaded with TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">, and one group, which received no treatment, served as control.The diameter of the spheroids ranged from 80 h6135232q3q/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">m to 350 h6135232q3q/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">m. There was no significant difference in growth between the 3 groups treated with h6135232q3q/xxlarge8216.gif" alt="lsquo" align="BASELINE" BORDER="0">freeh6135232q3q/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0"> TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">. Comparing spheroids treated with TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> with those which had been coincubated with empty liposomes, there was a significant difference (p<0.001) in growth, which correlated with the amount of liposomes. Similarly, free TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> had a significantly (P<0.001) stronger growth-inhibiting effect as compared to liposomes loaded with TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">. Comparing the groups treated with liposomes only to those treated with liposomes loaded with TNF-h6135232q3q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">, the latter exhibited a more marked (although not significantly) growth-inhibiting effect.The preliminary conclusion is that the major growth-inhibiting effect seems to be mediated by the liposomes. This phenomenon is in agreement with results obtained in monolayer cultures.     

Seroquel (ICI 204 636), a putative “atypical” antipsychotic,in schizophrenia with positive symptomatology: results of an open clinical trial and changes of neuroendocrinological and EEG parameters

Preclinical data indicated that seroquel (ICI 204 636), a dibenzothiazepine with 5-HT₂ and D₂-like receptor antagonistic properties, might be an effective antipsychotic agent, causing fewer extrapyramidal side effects than typical neuroleptics. In the present study, 12 patients suffering from schizophrenia or schizophreniform disorder with predominantly positive symptomatology were treated in an open clinical trial for 4 weeks with seroquel at a maximum dosage of 750 mg/day. The drug was generally well tolerated, and virtually no adverse extrapyramidal side effects such as acute dystonia, parkinsonism or akathisia were observed. Total scores for BPRS (item score 0–6; baseline: 42.0±2.3; mean±SeM), SAPS (64.5±4.8) and SANS (55.0±4.3) showed a moderate decrease at the end of treatment (BPRS: 30.0±3.5; SAPS: 36.1±6.7; SANS: 42.5±5.9), when intention-to-treat analysis was applied. There were considerable interindividual differences in treatment response, with some subjects showing almost full remission of positive symptoms, in contrast to about half of the patients who showed no satisfactory clinical improvement. Interestingly, patients showing good antipsychotic response reported slight initial side effects like mild sedation. Prolactin and TSH levels were not altered during seroquel administration. As to pharmaco-EEG investigations, seroquel caused a moderate increase of the absolute power in the alpha, theta, and beta frequency bands, paralleled by a decrease of delta activity. There were no signs of paroxysmal EEG activity under seroquel. Our results suggest that seroquel may be a well tolerated drug with some antipsychotic properties, exhibiting no extrapyramidal side effects that could be of use in the treatment of schizophrenic patients with positive symptomatology. Further double-blind studies with higher doses, in order to test presumably better efficacy, and with monitoring of plasma levels, are needed to extend the present results.     

Regioselectivity and Enantioselectivity of Metoprolol Oxidation by Two Variants of cDNA-Expressed P4502D6

Purpose. The oxidative metabolism of metoprolol was investigated in two human lymphoblastoma cell-lines transfected with variants of cDNA for cytochrome P4502D6. Methods. The regioselective and enantioselective features of the oxidations of deuterium-labeled pseudoracemic metoprolol were characterized by GC/MS analysis of the substrate and products. Results. There were significant differences between the two P4502D6 variants in the formation kinetics of O-demethylmetoprolol and -hydroxymetoprolol. The h2D6-Val microsomes highly favored the formation of the O-demethylmetoprolol regioisomer 6.3:1 and 2.8:1, respectively from (R)-metoprolol-d₀ and (S)-metoprolol-d₂, while the corresponding ratios for h2D6v2 microsomes were much lower. For both variants, O-demethylmetoprolol formation favored the (R)-substrate 1.5 to 2-fold, while -hydroxymetoprolol formation was non-enantioselective. Similar Km values of metoprolol oxidation, 10-20 µM, were observed for the two microsomal preparations. Conclusions. The regioselectivity, enantioselectivity, and Km values for the h2D6-Val microsomes resemble those observed for the native P4502D6 in human liver microsomes, whereas the h2D6v2 microsomes deviated remarkably in regioselectivity.     

Clinical application of18F-FUdR in glioma patients — PET study of nucleic acid metabolism

Summary Positron emission tomography was used to investigate the metabolism of nucleic acids by¹⁸F-fluoro-2h36uh1/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-deoxyuridine (¹⁸F-FUdR) in 22 patients with gliomas. Sixteen cases of high grade glioma clearly demonstrated a region of high activity with a differential absorption rate (DAR) of 0.64 ± 0.34. Six cases of low grade glioma failed to reveal a positive image of the tumor and the DAR in tumor was 0.21 ± 0.042 (p < 0.01). This PET-¹⁸F-FUdR study succeeded in differentiating high and low grade gliomas from the view point of nucleic acid metabolism.     

Infective endocarditis in paediatrics

Infective endocarditis is a result of infection of the endocardium, particularly of the heart valves (native or prosthetic valves). The most common causative organisms in the paediatric population are: Streptococci, Staphylococci and Enterococci. The classical signs of infective endocarditis like Roth spots, Janeway lesions, splinter haemorrhages and Osler's nodes are relatively rare in children. A high index of suspicion in a febrile child with a new murmur, detailed history, meticulous examination, repeated blood cultures, and echocardiography are essential in establishing the diagnosis. Management of infective endocarditis involves a prolonged course of antibiotics, at least for 4–6 weeks depending upon the causative organism and underlying heart condition. Complications of infective endocarditis include congestive heart failure resulting from valvular damage/regurgitation, infective emboli leading to abscesses in other organs and abnormal host immunological responses. Prophylactic antibiotics for dental and other medical procedures like genitourinary tract procedures are no longer recommended in the UK. The emphasis should be on educating children and their parents in early recognition of infective endocarditis. Children at high risk of developing endocarditis should be assessed urgently after clinical suspicion.     

Catecholamines modulate growth and differentiation of human preosteoclastic cells

Using a clonal cell line of human osteoclast precursors (FLG 29.1 cells), that after treatment with 12-O-tetradecanoyl phorbol 13-acetate (TPA) show many functional characteristics of osteoclasts, we demonstrated that catecholamines act as inducers of osteoclast maturation in vitro and as stimulators of osteoclast activity via the binding to h332124hq1/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₂ adrenergic receptors. Scatchard analysis of¹²⁵I-labelled iodocyano-pindolol to untreated (undifferentiated) or TPA-treated (differentiated) FLG 29.1 cells revealed the presence of a single high-affinity site with aK _d value around 24 pM and 8 pM respectively and with superimposable binding capacity (1.18 fmol/mg protein). Catecholamines increased in a dose-dependent fashion the intracellular cyclic AMP (cAMP) accumulation in both undifferentiated and TPA-treated FLG 29.1 cells. Pretreatment of untreated and TPA-treated FLG 29.1 cells with propranolol inhibited the catecholamine effect on cAMP accumulation, while pretreatment with clonidine had no effect. Catecholamines also reduced cell proliferation, increased tartrate-resistant acid phosphatase (TRAcP) activity, interleukin 6 (IL-6) production, multinuclearity and response to salmon calcitonin (sCT) in undifferentiated FLG 29.1 cells. In differentiated FLG 29.1 cells only IL-6 release was induced by catecholamine treatment. These findings support a potential role for catecholamines in modulating osteoclast differentiation and mature osteoclast activity.