Spontaneous haemoperitoneum in pregnancy and endometriosis: a case series.

OBJECTIVE: To report pregnancy outcomes of SHiP (spontaneous haemoperitoneum in pregnancy) and the association with endometriosis. DESIGN: Retrospective case note review. SETTING: Dutch referral hospitals for endometriosis. SAMPLE: Eleven women presenting with 15 events of SHiP. METHODS: In collaboration with the Dutch Working Group on Endometriosis, unpublished cases of SHiP that occurred in the Netherlands between 2010 and 2015 were retrieved. MAIN OUTCOME MEASURES: Maternal and perinatal mortality and morbidity. RESULTS: SHiP occurred predominantly in the second and third trimester of pregnancy. The earliest and major presenting symptom was an acute onset of abdominal pain, often combined with low haemoglobin levels or signs of fetal distress. Imaging was a diagnostic tool when free peritoneal fluid could be observed. For surgical treatment of the bleeding site, a midline laparotomy was mostly needed, the median estimated amount of blood loss was 2000 mL. No fetomaternal or perinatal mortality was reported, despite a high rate of preterm births (54.5%). In all women, endometriosis was diagnosed at a certain moment in time and therefore was probably involved in the pathogenesis of SHiP. Four women showed recurrence of SHiP. In one of these cases the second event of SHiP occurred in a subsequent pregnancy. CONCLUSION: Pregnancy outcomes of SHiP are improving when compared with previous reports, with absent fetomaternal and perinatal mortality in this recent series. Growing knowledge and adequate multidisciplinary intervention may have contributed to these favourable results. Increasing awareness of this serious complication of pregnancy is advocated, especially in women diagnosed with endometriosis. TWEETABLE ABSTRACT: Growing awareness of SHiP is advocated, especially in women diagnosed with endometriosis.

Perioperative outcomes using LigaSure compared with conventional bipolar instruments in laparoscopic hysterectomy: a randomised controlled trial.

OBJECTIVE: To compare the effects of LigaSure versus the conventional bipolar technique on operating time and blood loss during laparoscopic hysterectomy. DESIGN: A randomised controlled trial. SETTING: Three teaching hospitals. POPULATION: Women undergoing a laparoscopic hysterectomy for benign indications. METHODS: 140 women undergoing a laparoscopic hysterectomy were randomised for LigaSure or conventional bipolar instruments. MAIN OUTCOME MEASURES: Primary outcome was operating time from initial skin incision till detachment of the uterus. Secondary outcome measures were total operating time (from initial skin incision till final skin closure), time to dissect the adnexal ligaments, intra-operative blood loss and subjective evaluation by the surgeon of the instrument used. RESULTS: No differences in operating time (from initial skin incision till uterine detachment and initial skin incision till final skin closure) using LigaSure versus conventional bipolar instruments: 97.6 versus 91.8 minutes (P = 0.39, 95% CI - 7.6 to 19.2), and 148.1 versus 142.1 minutes (P = 0.46, 95% CI - 10.1 to 22.3), respectively. The mean blood loss using LigaSure versus conventional bipolar was 234.1 versus 273.1 ml (P = 0.46, 95% CI -39.1 to 52.7). Various subjective efficacy and instrument handling parameters were significantly different between the two instruments and between the different participating centres. CONCLUSIONS There were no significant differences in operating time and blood loss between the use of LigaSure and the use of conventional bipolar instruments during laparoscopic hysterectomy, even after correction for potential confounders. User satisfaction parameters were assessed as significantly different by surgeons of the participating centres.

Recommendations to prevent urinary tract injuries during laparoscopic hysterectomy: a systematic Delphi procedure among experts.

STUDY OBJECTIVE: To reach consensus among experts in the field of laparoscopic gynaecology in uniform recommendations on the prevention and early detection of urinary tract injuries during laparoscopic hysterectomy (LH). DESIGN: A systematic Delphi consensus procedure (Canadian Task Force Classification III). SETTING: A tertiary-care university hospital. POPULATION: International gynecologic experts in the field of LH. METHODS: Experts were selected according to standard criteria with regard to surgical experience and research. Twenty of 40 experts were willing to participate. Three questionnaires were sent. Each questionnaire was formulated and based on the answers of the previous one. RESULTS: Fourteen experts completed the third questionnaire. In 40 of 65 proposed recommendations, consensus was achieved. Consensus was achieved with respect to required education, learning curve, equipment, restoration of distorted anatomy and on the application of diagnostic tools in early detection of urinary tract injuries. CONCLUSION: The Delphi technique is a useful tool to achieve consensus regarding urologic complications in LH. Recommendations may serve as a basis for further research and the development of educational programs.

Hysterectomy or a minimal invasive alternative? A systematic review on quality of life and satisfaction.

Nowadays, an increasing number of minimal invasive treatment alternatives to hysterectomy may be offered to the patient. In determining the appropriate treatment option, the patient has a distinct dilemma if a minimal invasive treatment with lesser effect than hysterectomy should be chosen or if a hysterectomy should be chosen which is a major surgery and requires longer recovery than the minimal invasive alternative. Quality-of-life (QoL) questionnaires that take subjective health perception into account are currently used to assess the treatment effects. The objective of this literature study is to determine and discuss the role of QoL as an outcome in randomized controlled trials (RCT) or systematic reviews of RCTs that study the treatment effect of hysterectomy compared to that of minimal invasive alternatives. A systematic literature search was performed in the PubMed database and in the Cochrane database to find randomized trials and systematic reviews of randomized trials, comparing hysterectomy with minimal invasive or conservative treatment options with sufficient follow-up using satisfaction, health status, and quality of life as outcomes. The results were based on nine randomized trials and two systematic reviews. The differences are mostly in favor of hysterectomy. In two out of four studied treatment alternatives, the satisfaction or health status is different in favor of hysterectomy while the QoL is equivalent. After 2 years of follow-up, differences between both groups have disappeared, possibly because of the crossover effect. Possible reasons for the lesser response of QoL compared to satisfaction or health status are discussed. The fundamental question if patients have a better quality of life at all times if they choose for a minimal invasive alternative of hysterectomy remains unresolved. Information, individualization, and freedom of choice before surgery probably best serve the sense of well being and quality of life thereafter.

Endogenous dopamine limits the binding of antipsychotic drugs to D3 receptors in the rat brain: a quantitative autoradiographic study.

[3H]7-hydroxy-N,N-di-n-propyl-2-aminotetralin was used as a radioligand for the autoradiographic measurements of dopamine D3 receptors in rat and human brain. Preincubation of the brain sections was necessary to obtain binding of the radioligand in the islands of Calleja and in the nucleus accumbens, but not in cerebellar lobules 9/10 of the rat. D3 receptors were also totally occluded in unwashed sections of the human striatum. The radioligand binding to D3 receptors was maximal after preincubating the sections for at least 10 min. Pretreatment of the animals with reserpine or tetrabenazine, which results in a severe depletion of endogeneous monoamines, strongly reduces the occlusion of D3 receptors in unwashed brain sections. The occlusion of dopamine D3 receptors in brain sections suggests that the in vivo access to D3 receptors may be locally inhibited by endogenous dopamine. The in vitro binding affinities of 12 antipsychotic drugs for D2 and D3 receptors were evaluated in competition binding experiments, using both rat and cloned human receptors. Most of the compounds showed only a slightly lower affinity for D3 than for D2 receptors in vitro. Affinities of the antipsychotic drugs for cloned human D21 and D3 receptors were very close to their affinities for the rat receptors. In vivo occupancy of these receptors in the rat brain was measured ex vivo by quantitative autoradiography, 2 hours after subcutaneous drug administration. For most compounds, occupancy of D3 receptors, as compared to D2 receptor occupancy, was lower than expected from the corresponding in vivo affinity ratios. For the new antipsychotic risperidone, in vivo occupancy of D3 receptors was measured both in the islands of Calleja and in the cerebellar lobules 9/10. This compound was three times less potent for the occupancy of D3 receptors in the islands of Calleja than in the cerebellum, an area lacking endogenous dopamine (ED50 = 28 and 10 mg kg-1, respectively). Based on the observations in the rat brain, it may reasonably be supposed that therapeutic dosages of antipsychotic drugs will induce in patients only a minor occupancy of D3 receptors in brain areas containing high dopamine concentrations. The role of dopamine D3 receptors as a target of antipsychotic drugs may therefore be less important than previously thought.

Risperidone compared with new and reference antipsychotic drugs: in vitro and in vivo receptor binding.

Risperidone and its active metabolite 9-OH-risperidone were compared to reference antipsychotic drugs (haloperidol, pipamperone, fluspirilene, clozapine, zotepine) and compounds under development (olanzapine, seroquel, sertindole, ORG-5222, ziprasidone) for in vitro binding to neurotransmitter receptors in brain tissue and on membranes of recombinant cells expressing cloned human receptors and for in vivo occupancy of neurotransmitter receptors in rat and guinea-pig brain following acute treatment (2 h., s.c.). An ex vivo autoradiography technique was applied to determine the receptor occupancy by the drugs administered in vivo. Of particular interest are the central 5HT2A receptors and D2-type receptors. Predominant 5HT2A receptor antagonism is supposed to add to an atypical profile of the antipsychotics (treatment of the negative symptoms, low incidence of extrapyramidal side effects). D2 antagonism is required the treatment of positive symptoms. A contribution of the new dopamine receptor subtypes D3 and in particular D4 receptors has been proposed. In vitro, all compounds, except the 'typical' antipsychotics haloperidol and fluspirilene, showed higher affinity for 5HT2A than for D2 receptors. Subnanomolar affinity for human 5HT2A receptors was observed for ORG-5222, sertindole, risperidone, 9-OH-risperidone and ziprasidone. Fluspirilene, ORG-5222, haloperidol, ziprasidone, risperidone, 9-OH-risperidone and zotepine displayed nanomolar affinity for human D2 receptors. Sertindole and olanzapine were slightly less potent. Pipamperone, clozapine and seroquel showed 2 orders of magnitude lower D2 affinity in vitro. Clozapine, but even more so pipamperone, displayed higher affinity for D4 than for D2 receptors. For most other compounds, D4 affinity was only slightly lower than their D2 affinity. Seroquel was totally devoid of D4 affinity. None of the compounds had nanomolar affinity for D1 receptors; their affinity for D3 receptors was usually slightly lower than for D2 receptors. In vivo, ORG-5222, risperidone, pipamperone, 9-OH-risperidone, sertindole, olanzapine, zotepine and clozapine maintained a higher potency for occupying 5HT2A than D2 receptors. Risperidone and ORG-5222 had 5HT2A versus D2 potency ratio of about 20. Highest potency for 5HT2A receptor occupancy was observed for ORG-5222 followed by risperidone and olanzapine. Ziprasidone exclusively occupied 5HT2A receptors. ORG-5222, haloperidol, fluspirilene and olanzapine showed the highest potency for occupying D2 receptors. No regional selectivity for D2 receptor occupancy in mesolimbic versus nigrostriatal areas was detected for any of the test compounds. Risperidone was conspicuous because of its more gradual occupancy of D2 receptors; none of the other compounds showed this property. The various compounds also displayed high to moderate occupancy of adrenergic alpha 1 receptors, except fluspirilene and ziprasidone. Clozapine, zotepine, ORG-5222 and sertindole occupied even more alpha 1 than D2 receptors. Clozapine showed predominant occupancy of H1 receptors and occupied cholinergic receptors with equivalent potency to D2 receptors. A stronger predominance of 5HT2A versus D2 receptor occupancy combined with a more gradual occupancy of D2 receptors differentiates risperidone and its 9-OH-metabolite from the other antipsychotic compounds in this study. The predominant 5HT2A receptor occupancy probably plays a role in the beneficial action of risperidone on the negative symptoms of schizophrenia, whereas maintenance of a moderate occupancy of D2 receptors seems adequate for treating the positive symptoms of schizophrenia. A combined 5HT2A and D2 occupancy and the avoidance of D2 receptor overblockade are believed to reduce the risk for extrapyra

In vitro receptor binding and in vivo receptor occupancy in rat and guinea pig brain: risperidone compared with antipsychotics hitherto used.

Risperidone was compared with antipsychotics hitherto used for in vitro receptor binding using animal brain or cloned (human) receptors and in vivo receptor occupancy in rat and guinea pig brain following acute treatment. Both in vitro and in vivo, risperidone, 9-OH-risperidone, SM-9018, clozapine and clocapramine showed higher affinity for 5-HT2A- than for D2-receptors, whereas mosapramine, haloperidol, bromperidol and nemonapride had a slight to strong preference for D2- compared to 5-HT2A-receptors. In vivo, risperidone showed the highest potency for 5-HT2A-receptor occupancy; To obtain the same extent of D2-receptor occupancy, a 19-times higher dosage was required. 9-OH-Risperidone, the principal active metabolite of risperidone, showed a receptor occupancy profile comparable to that of risperidone. No regional selectivity for D2-receptor occupancy in mesolimbic vs nigrostriatal areas was detected for any of the compounds. Risperidone differed from the other compounds by the remarkably shallow slope of its D2-receptor dose-occupancy curve. A greater predominance of 5-HT2A-receptor vs D2-receptor occupancy and a more gradual occupancy of D2-receptors differentiate risperidone from the other compounds. Both properties probably assist in preventing an extensive blockade of D2-receptors, the cause for extrapyramidal symptoms (EPS). The predominant 5-HT2A-receptor occupancy most likely underlies risperidone's beneficial effects on the negative symptoms of schizophrenia and an adequately low D2-receptor occupancy adds to the treatment of positive symptoms with a low liability of EPS.

Occupancy of central neurotransmitter receptors by risperidone, clozapine and haloperidol, measured ex vivo by quantitative autoradiography.

Risperidone (Risperdal) is a novel antipsychotic drug, with beneficial effects on both positive and negative symptoms of schizophrenia, and with a low incidence of extrapyramidal side effects (EPS). These particular properties have been attributed to the predominant and very potent serotonin 5-HT2 receptor antagonism of the drug combined with less potent dopamine D2 antagonism. In order to provide data on the degree to which various central neurotransmitter receptors are occupied in vivo, we performed ex vivo receptor occupancy studies with risperidone in comparison with clozapine and haloperidol in rats and guinea pigs. Various types of receptors, to which the compounds were known to bind to in vitro, were investigated precisely using receptor autoradiography in sections of the same rat brain except for histamine H1 receptors that were measured in the guinea-pig cerebellum. Risperidone (2 h after s.c. treatment) occupied 5-HT2 receptors at very low doses (ED50 = 0.067 mg/kg). Nearly full occupancy (> 80%) was achieved before H1, D2, alpha 1 and alpha 2 receptors became occupied (ED50 = 0.45, 0.66, 0.75 and 3.7 mg/kg, respectively). Clozapine displayed occupancy of H1 and alpha 1 receptors at low doses (ED50 = 0.15 and 0.58 mg/kg, respectively) and of 5-HT2, 5-HT1C, D2, alpha 2, cholinergic muscarinic and 5-HT1A receptors at higher doses (ED50 = 1.3, 1.8, 9.0, 9.5, 11 and 15 mg/kg, respectively). Haloperidol occupied D2 and alpha 1 receptors at low doses (ED50 = 0.13 and 0.42 mg/kg, respectively) and 5-HT2 receptors at a higher dose (ED50 = 2.6 mg/kg). Occupancy of receptor types occurred with similar ED50-values in various brain areas, e.g. D2 receptors in striatum and mesolimbic areas. The ED50-values for the ex vivo measured occupancy of 5-HT2 and D2 receptors were in good agreement with ED50-values for functional effects putatively mediated by these central receptors. The dose-dependent occupancy of D2 receptors proceeded more gradually with risperidone (slope in the caudate-putamen: 0.85) than with clozapine (slope: 1.44) or haloperidol (slope: 1.51). It has previously been suggested that partial D2 receptor occupancy may suffice to control the positive symptoms of schizophrenia, whereas higher D2 receptor occupancy would induce extrapyramidal symptoms (EPS). The dose ratio for high (75%) vs. low (25%) D2 receptor occupancy in the caudate-putamen, was 37.3 for risperidone, 8.4 for clozapine, and 7.9 for haloperidol.(ABSTRACT TRUNCATED AT 400 WORDS)

Autoradiographic evidence for the occlusion of rat brain dopamine D3 receptors in vivo.

[125I]Iodosulpride binding was studied in frontal rat brain sections by quantitative autoradiography. Using preincubated (= washed) sections, selective labelling and identification of dopamine D3 receptors was obtained using 0.2 nM [125I]iodosulpride in the presence of 100 nM domperidone for the occlusion of the D2 receptors. A high density of D3 receptors was noticed in the islands of Calleja. When preincubation of the sections was omitted, no D3 receptor labelling could be achieved, indicating tight binding to the receptor of an endogenous inhibitor. Such a tight receptor occupancy was not observed for the D2 receptor and various other neurotransmitter receptors. The occlusion of the D3 receptor could be prevented by tetrabenazine-induced monoamine depletion of the rats. It can be concluded, therefore, that D3 receptors are massively occupied by a monoamine, likely to be dopamine. This observation prompts the question to what extent dopamine D3 receptors can become occupied in vivo by systematically applied exogenous compounds.

[Non-sedative antihistaminics and binding to central and peripheral H1 histamine receptors]. / Antihistaminiques non-sédatifs et liaison aux récepteurs histaminergiques-H1 centraux et périphériques.

Four non-sedating antihistamines (astemizole, cetirizine, loratadine and terfenadine) were investigated for in vitro and ex vivo binding to histamine-H1 receptors in guinea-pig cerebellum and lung. In vitro, all the drugs dissociated slowly from H1 receptors (half-times greater than or equal to 100 min), Ki,app-values decreased with longer incubation times for potent lipophylic agents (astemizole and terfenadine) Ki,app-values were lower with more dilute tissue suspensions. In optimized assay conditions astemizole showed a Ki,app-value of 0.2 microM. Terfenadine, cetirizine and loratadine bound with 30-, 80- and 100-times lower affinity to H1 receptors. The occupancy of lung and cerebellar H1 receptors was investigated after oral administration of various dosages of the drugs and at several times after drug administration, using ex vivo binding techniques. Astemizole was a very potent compound showing complete differentiation between lung and cerebellar receptor occupation (with 0.63 mg/kg: 70% of lung H1 receptors were occupied, with less than 10% of cerebellar H1 receptor occupancy). A 7-times higher dose of terfenadine was required to induce the same effect. Astemizole produced a rapid and complete occupancy of lung receptors, which was maintained up to 72 h after administration. In contrast, terfenadine produced a peak effect at 1 h and was completely eliminated from lung receptors in 24 h. Loratadine and cetirizine only poorly differentiated between lung and cerebellar receptor occupancy (at 2.5 mg/kg: 70 and 60% of lung receptor occupancy, 50 and 70% of cerebellar receptor occupancy).(ABSTRACT TRUNCATED AT 250 WORDS)

The light-dark cycle modulates the effects of ritanserin on sleep-wakefulness patterns in the rat.

The 5-HT2 receptor antagonist ritanserin (0.63 mg/kg IP) produced differential effects on sleep-wakefulness patterns in rats when administered during the light or dark period: an increase in the duration of deep slow wave sleep at the expense of light slow wave sleep, paradoxical sleep and wakefulness when injected during the light period, and no major sleep alteration when given at dark onset. Since circadian variations in serotonin receptor density might modulate the sleep response, we examined the effects of ritanserin on sleep in rats exposed to continuous light for 10 days, and whether 5-HT2 receptors were affected in separate groups of rats exposed to similar conditions. No significant changes in the KD- and Bmax -values of various receptors were found. However, ritanserin produced greater effects in continuous light conditions than when given during the light period in the 12-hr light-dark condition. This suggests a possible role of 5-HT2 receptors in the organization of sleep when the environmental photoperiod is disturbed.

Receptor occupancy by ritanserin and risperidone measured using ex vivo autoradiography.

In this study, autoradiographical techniques are introduced to investigate the occupancy of serotonin 5-HT2, dopamine D2 and alpha 1-adrenergic receptors after the in vivo administration of ritanserin, a selective, potent and long-acting 5-HT2 antagonist and of risperidone, a very potent 5-HT2 antagonist and potent D2 and alpha 1 antagonist. Unoccupied 5-HT2 and alpha 1-receptors were labelled with [125I]7-amino-8-iodoketanserin ([125I]AMIK) and D2 receptors with [125I]iodosulpride in horizontal rat brain section. Receptor occupancy by the drugs was quantified by image analysis of the autoradiograms. Ritanserin produced 50% occupancy of the 5-HT2 receptors at a dose of 0.02 mg/kg s.c., while at 40 mg/kg s.c. ritanserin still did not occupy 50% of the D2 and alpha 1 receptors. Risperidone occupied 50% of the 5-HT2, alpha 1 and D2 receptors at 0.0075, 0.32 and 2.5 mg/kg s.c., respectively. Ex vivo autoradiography was found to be applicable where radioligand binding techniques using brain homogenates had failed for the study of ex vivo receptor occupancy due to rapid drug dissociation. Ex vivo autoradiography is hitherto the sole technique which allowed the measurement of alpha 1 receptor occupancy by risperidone after in vivo administration of the drug.

Rapid desensitization and down-regulation of 5-HT2 receptors by DOM treatment.

The regulation of the 5-HT2 receptor-mediated head twitch response and of 5-HT2 receptor binding in the frontal cortex was studied in rats treated repeatedly with the 5-HT2 agonist 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) (2.5 mg/kg, s.c.). Four injections in 24 h produced a near maximal reduction in the behaviour (-70%) and in the Bmax for [3H]ketanserin binding (-41%). The KD values tended to increase slightly. 5-HT2 receptors reappeared, with half-lives of 5.5 to 3 days. In view of the reported anomalous 5-HT2 receptor regulation by antagonists and the regular regulation by agonists, we propose a refinement in the receptor regulation theory.

Receptor interactions of dopamine and serotonin antagonists: binding in vitro and in vivo and receptor regulation.

The advent of receptor binding techniques has provided new ways of studying the mechanism of action of drugs. In vitro radioligand binding is now currently applied to investigate the specificity or multiple action of compounds. By using the same technique, the binding affinity of a drug can be measured for a variety of neurotransmitter, drug, peptide and ion channel receptor binding sites, providing the drug's receptor binding profile (LEYSEN et al. 1981; LEYSEN 1984). However, in vitro receptor binding is only the initial step in the investigation of drug-receptor interactions. Investigations in vivo are required to allow evaluation of how and where a drug acts. In fact, the study of drug-receptor interactions comprises three main stages: (a) in vitro radioligand receptor binding; (b) in vivo receptor binding, providing information on the accessibility of the drugs to the receptors localized in various central and peripheral tissues, on the drug potency for occupying various receptors, on the duration of receptor occupation and on the relationship between the degree of receptor occupation and pharmacological effects; and (c) the study of receptor regulation: the effect of chronic drug treatment on receptor alterations compared with alterations in functional responses in vivo. In this article, we will illustrate the three stages of investigation of receptor interactions and discuss the relevance and importance of the findings, using as examples three drugs known in psychopharmacological research: (a) the neuroleptic haloperidol, a prototype of a dopamine D2 antagonist: (b) Setoperone, a potential antipsychotic agent with very potent serotonin S2 and moderate D2 antagonistic activity (CEULEMANS et al. 1985; LEYSEN et al. 1986); and (c) ritanserin, a potent and long-acting S2 antagonist (LEYSEN et al. 1985), which has revealed therapeutic activity in dysthymia and negative symptoms of schizophrenia (REYNTJENS et al. 1986; GELDERS et al. 1986). Particular attention will be paid to the problem of receptor regulation. We challenge the general applicability of the receptor regulation theory, which states that persistent receptor stimulation causes desensitisation and receptor downregulation, whereas chronic deprivation of receptor stimulation leads to supersensitivity and receptor upregulation. Recent research has revealed that the theory does not hold for S2 receptor alterations, which were found to downregulate following chronic receptor blockade.

Axonal transport of the synaptic vesicle monoamine carrier identified by [3H]dihydrotetrabenazine binding in rat sciatic nerve.

The monoamine carrier of noradrenergic synaptic vesicles was assayed in the rat sciatic nerve by in vitro binding of [3H]dihydrotetrabenazine. The number of binding sites increased with time on both sides of a ligature, indicating fast anterograde and retrograde axoplasmic transports of comparable amplitude. Anterogradely and retrogradely transported binding sites had similar pharmacological properties, which were characteristic of binding to the monoamine carrier embedded within a lipid bilayer. Contrary to the secreted synaptic vesicle matrix constituents, the intrinsic monoamine carrier assayed by [3H]dihydrotetrabenazine binding is a marker adapted to retrograde transport studies.

Impaired axonal transport of opiate and muscarinic receptors in streptozocin-diabetic rats.

Axonal transport of receptors was studied in streptozocin-diabetic rats using two different binding models. Streptozocin-induced hyperglycemia caused a reduced accumulation of muscarinic receptors above a ligature placed on rat sciatic nerves when the binding assay was performed in vitro with [3H]QNB. In the vagus nerve, the retrograde axonal transport of receptor-bound opiate was strongly decreased in the streptozocin-treated rats when [3H]lofentanil was used in vivo to label opiate receptors. Insulin partly reversed the changes observed in the streptozocin-treated rats. These findings suggest that impaired axonal transport of receptors may explain part of the neurological disturbance which is seen in diabetic patients.

Opiate receptors in brain labelled in vivo with [3H]lofentanil.

The in vivo binding of [3H]lofentanil was studied in various regions of the brain in rat. After intravenous injection of [3H]lofentanil the disposition of the labelled drug in the brain paralleled exactly the regional distribution of opiate receptors measured in in vitro binding assays. The labelling was saturable and could be prevented by naloxone when given before [3H]lofentanil, in all the regions except in the cerebellum. The long-lasting occurrence of the specific labelling was entirely compatible with the extremely slow dissociation rate of lofentanil and its long duration of action. This explains why [3H]lofentanil is not displaceable by naloxone in vivo. Subcellular fractionation experiments revealed that all the labelling in the frontal cortex but not in the cerebellum was particulate-bound and entirely displaceable by naloxone. The advantages of [3H]lofentanil in vivo are its extremely low non-specific binding and its ability to reveal very low occupancy of opiate receptors in brain.

Receptor-binding properties in vitro and in vivo of ritanserin: A very potent and long acting serotonin-S2 antagonist.

In vitro and in vivo receptor-binding properties of the new serotonin antagonist, ritanserin, are reported. In in vitro binding assays, ritanserin shows high affinity binding to serotonin-S2 sites in rat frontal cortex tissue: IC50 = 0.9 nM without drug preincubation and 0.3 nM with 30-min drug preincubation; IC50 values for histamine-H1, dopamine-D2, and adrenergic-alpha 1 and -alpha 2 sites were 39-, 77-, 107-, and 166-fold higher, and at up to 1 microM, the drug did not bind to serotonin-S1 sites. In in vitro assays, ritanserin dissociated very slowly from serotonin-S2 (t1/2 = 160 min) and histamine-H1 sites (t1/2 = 77 min) and rapidly from dopamine-D2 sites (t1/2 = 11 min). Half-times of dissociation from adrenergic-alpha 1 and -alpha 2 sites were 18 and 26 min. The inhibition by ritanserin of [3H]ketanserin binding was found to be partially noncompetitive and the inhibitory potency increased with drug preincubation. Due to the slow dissociation of ritanserin from the serotonin-S2 sites, the drug cannot be displaced completely by [3H]ketanserin. In contrast, inhibition by ritanserin of [3H]haloperidol binding to dopamine-D2 sites in rat striatum was fully competitive, in agreement with the rapid dissociation of the drug from the latter sites. In ex vivo binding assays using brain areas of rats and guinea pigs treated subcutaneously with ritanserin, occupation of serotonin-S2 sites was observed at very low dosage (50% occupation at 0.08-0.1 mg/kg) and sites remained occupied during a prolonged time period (greater than 70% occupation up to 48 hr after 2.5 mg/kg ritanserin). Histamine-H1 receptor sites in guinea pig cerebellum became occupied at dosages 25-fold higher than the dosage producing occupation of frontal cortical serotonin-S2 sites. Dopamine-D2 sites in rat striatum and cortical adrenergic-alpha 1 sites became only slightly occupied (less than 20%) at higher dosages and the effect was not dose-dependent. Adrenergic-alpha 2 sites were not occupied up to doses of 160 mg/kg given subcutaneously. In vivo binding assays using [3H]spiperone confirmed the occupation of frontal cortical serotonin-S2 sites following low dosage of ritanserin and a minor occupation of striatal dopamine-D2 sites. Levels of dopamine and serotonin and their metabolites remained unchanged in brain areas of rats orally treated with ritanserin up to dosages of 40 mg/kg. At 160 mg/kg, there seemed to be a slight reduction in dopamine and serotonin content.(ABSTRACT TRUNCATED AT 400 WORDS)

Retrograde axonal transport of receptor-bound opiate in the vagus and delayed accumulation in the nodose ganglion.

Opiate receptors measured in vivo with [3H]lofentanil in the rat vagus nerve were found to accumulate on both sides of a ligature. The time-course of accumulation was completely different in the proximal and the distal segments; the labelling was maximal 4 h after injection of [3H]lofentanil above the ligature but 16-24 h below the ligature. In unligated rats, a peak of radioactivity appeared in the nodose ganglion 16 h after injection; vagotomy, vinblastine or chronic treatment with capsaicin prevented the appearance of this delayed accumulation in the ganglion. These foregoing experiments suggest that opiate may act in the cell body of sensory neurones after being internalized at the nerve terminals and then transported retrogradely through fast axoplasmic mechanisms.