Hippocampal loss of the GABAA receptor α1 subunit in patients with chronic pharmacoresistant epilepsies

Alterations of gamma aminobutyric acid (GABA)-mediated neurotransmission have been implicated in the pathogenesis of epilepsies. Here we examine the distribution of the GABA_A receptor in the hippocampus of 78 surgical specimens from patients with chronic pharmacoresistant focal epilepsies. The receptor was localized immunohistochemically with the monoclonal antibody bd-24 which selectively recognizes the ₁ subunit of the GABA_A receptor. The results were compared with the receptor distribution of 28 normal hippocampal specimens obtained at autopsy. In the great majority of the surgical specimens a loss of GABA_A receptor immunoreactivity was present in CA1 (92.3%), CA4 (78.2%), the dentate granular cell layer (70.5%) and the molecular layer of the dentate gyrus (65.4%). The subiculum revealed a normal staining pattern in all but 4 cases. In no instance did we observe an increase of immunoreactivity in any region or cell population. The decrease of GABA_A receptor immunoreactivity was closely related to neuronal loss in the respective specimen and to Ammon's horn sclerosis. There was no correlation between GABA_A receptor loss and the patient's age at surgery, duration of seizures, age at onset of seizures and to the presence or absence of secondary generalized tonic clonic seizures. The data suggest that the observed loss of GABA_A receptor immunoreactivity is a secondary phenomenon rather than an event that is relevant for the pathogenesis of epileptic seizures.     

Presynaptic opioid receptors on dopaminergic nerves in the rabbit caudate nucleus: coupling to pertussis toxin-sensitive G-proteins and interaction with D2 autoreceptors?

Slices of the rabbit caudate nucleus, preincubated with [³H]dopamine and subjected to electrical field stimulation, were used (1) to investigate the involvement of G-proteins in the signal transduction of presynaptic D₂ (auto)receptors and -opioid receptors on dopaminergic axon terminals in this tissue and (2) to study a possible mutual interaction of these two presynaptic receptors. Pretreatment of the slices with either pertussis toxin (8 g/ml; 18 h), or N-ethylmaleimide (30 M, 30 min) significantly reduced the inhibitory effects of both the D₂ agonist quinpirole and the -opioid receptor agonist U-50488H on the [³H]overflow evoked by 36 pulses (2 ms, 24 mA, 0.3 Hz), suggesting the coupling of both receptors to G-proteins.Experiments designed to study possible interactions of these two presynaptic receptors were carried out under stimulation conditions (only 1 pulse), which strongly diminish interference of endogenous transmitters released in the tissue with modulatory effects of exogenous drugs. For instance, due to the presence of endogenous dopamine, quinpirole was much less potent during 36-pulse-than during 1-pulse field stimulation, whereas the D₂ antagonist domperidone was almost without effect in the latter case. Using the 1-pulse stimulation paradigm, the concentration/response curve of quinpirole was unaffected in the presence of the halfmaximal inhibitory concentration of U-50,488 H (0.1 M). On the other hand, also quinpirole at its halfmaximal inhibitory concentration (0.1 M), hardly affected the concentration/response curve of U-50,488 H: only high concentrations of U-50,488 H (above 1 M) seemed to be slightly less effective in the presence than in the absence of the D₂ agonist. U-50,488 H, at these high concentrations, was also less potent under 36-pulse than under 1-pulse stimulation conditions. From these findings, we conclude that there is only a limited interaction between presynaptic D₂ autoreceptors and -opioid receptors on dopaminergic axon terminals in the rabbit caudate nucleus, despite they are both coupled to PTX/NEM-sensitive G-proteins. Correspondence to: R. Jackisch at the above address     

In vivo labeling of sigma receptors in mouse brain with [3H]4-phenyl-1-(4-phenylbutyl)piperidine

4-Phenyl-1-(4-phenylbutyl)piperidine(4-PPBP) is a very potent ligand for σ (Sigma) receptors. The present study was undertaken to evaluate [³H]4-PPBPas a radioligand for in vivo labeling of cerebral σ receptors. After intravenous administration of [³H]4-PPBP to mice, there is high uptake of radioactivity in the brain. The regional distribution of radioactivity in the brain 2 h after intravenous injection of [³H]4-PPBP parallels the in vitro binding of the radioligand in rat brain (pons/medulla > cerebellum ≥ prefrontal cortex ≥ parietal cortex > hypothalamus > olfactory tubercle ≥ thalamus > hippocampus > striatum). Pretreatment with haloperidol (2 mg/kg) significantly decreases the radioactivity measured in the brain 30–120 min after injection of [³H]4-PPBP. Pretreatment with unlabeled 4-PPBP or ifenprodil also significantly decreases radioactivity in the brain 2 h after injection of [³H]4-PPBP, in a dosedependent manner. The in vivo binding of [³H]4-PPBP in the brain also is significantly inhibited by SL 82.0715, BMY 14802, 1,3-di-o-tolylguanidine (DTG), and (+)-enantiomers of pentazocine, SKF 10,047, and 3-PPP, but not by the corresponding (?)-enantiomers, consistent with stereoselectivity of inhibition obtained in in vitro binding studies. In contrast, pretreatment with dizocilpine and spiperone does not inhibit in vivo binding of [³H]4-PPBP. The results indicate that [³H]4-PPBP would be a suitable radioligand for in vivo labeling of σ receptors in brain. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America

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慢性癫痫大鼠脑组织生长抑素受体功能的变化

探讨癫痫发病的生化机制。方法用１２５Ｉ－ＳＯＭ作为配基,采用放射性配基受体结合分析法,对戊四氮诱导的慢性癫痫大鼠海马生长抑素（ＳＯＭ）受体功能进行了测定。结果慢性癫痫大鼠及对照组海马ＳＯＭ受体的Ｂｍａｘ值分别为２４６．０±１８．２ｐｍｏｌ／ｇ蛋白质及２２０．０±１５．３ｐｍｏｌ／ｇ蛋白质,Ｋｄ值分别为４．１９±０．３４ｎｍｏｌ／Ｌ及３．８９±０．２２ｎｍｏｌ／Ｌ。常用的抗痫药卡马西平（ＣＢＺ）、丙戌酸钠（ＶＰＡ）及钙桔抗剂尼莫地平（ＮＩＭ）能降低受体的亲和力,而苯妥因钠（ＰＨＴ）则无影响。结论ＳＯＭ受体活性增高在癫痫发病中起着重要作用,常用抗痫药的抗痫活性可能与其降低ＳＯＭ受体活性有关。     

Modification of sexual behavior of Long-Evans male rats by drugs acting on the 5-HT1A receptor

Modulation of the sexual behavior of male rats by the anxiolytic buspirone (S-20499) and its analog gepirone were compared to the effects of 8-OH-DPAT (or DPAT, a selective 5-HT1A reference agonist), and BMY-7378 (a selective 5-HT1A partial agonist). Long-Evans rats were used; modulation of copulatory behavior and alteration of penile reflexes were examined. Modulation of copulatory behavior was assessed by three indices: frequency and length of intromission, and latency of ejaculation. DPAT, at doses of 1-8 mg/kg, reduced these three indices in a time dependent manner such that the effects peaked at 45 min and normalized at 90 min. The dose-effect relationship (assessed 45 min after DPAT injection) is bell-shaped with an ED50 approximately 1 mg/kg on the ascending limb of the curve. The effects of buspirone (2 mg/kg) and gepirone (2 mg/kg) on copulatory behavior were indistinguishable from control. BMY-7378 alone and in combination with these other 5-HT1A agonists reduced copulatory behavior, though not statistically significant. Penile reflexes, including number of erections, cups and flips, were inhibited by these agents: DPAT>buspirone>gepirone (inactive at 2 mg/kg). Furthermore, the latency period to erection was at least doubled by DPAT (2 mg/kg). Buspirone and gepirone, however, reduced the latency period to erection. BMY-7378 inhibited penile reflexes when administered alone and even more in combination with DPAT or buspirone. Two butyrophenone analogs, spiperone (a 5-HT1A and dopamine D2 antagonist) and haloperidol (a D2 antagonist), were also tested for their interaction with DPAT. Both of these drugs (at 0.25 mg/kg, 60 min after administration) reduced all indices of penile reflexes and copulation. Furthermore, in combination with DPAT (2 mg/kg, 45 min), the effects were synergistic such that sexual activity came nearly to a standstill. These opposing effects on putatively brain originated copulatory behavior and spinal mediated penile reflexes indicate that the effects of buspirone and DPAT on sexual behavior in the male rat may be possible at different parts of the central nervous system. If a tentative shared target site by DPAT and buspirone is the 5-HT1A receptor, than the same 5-HT receptor sub-type at different locations (brain, raphe nuclei, spinal cord and autonomic ganglia) may modulate rat sexual behavior in opposing ways.     

Neuropeptide families and their receptors: evolutionary perspectives

Examination of families of neuropeptides and their receptors can provide information about phyletic relationships and evolutionary processes. Within an individual a given signal molecule may serve many diverse functions, mediated via subtypes of the receptor which may be coupled to their transduction mechanisms in different ways. The rate of evolution of a peptide may reflect or be reflected in the rate of evolution of its receptor. For example, in the neuropeptide Y (NPY) family, pancreatic polypeptide (PP) shows significant structural diversity, while NPY is highly conserved. Molecular forms of a given subtype of NPY receptor that is selectively activated by NPY (Y1 or Y2 or Y5) are also highly conserved, but the subtype that is primarily activated by PP (Y4), shows remarkable diversity. Also, between receptor subtypes there can be remarkable diversity. This is evident in several neuropeptide families, where a neuropeptide sequence is highly conserved across a wide range of species but where the receptor homology of subtypes with species tends to be much lower than homology between species. For example, human and rat vasopressin are identical, but the human V₁- or V₂-vasopressin receptors are approximately 80% homologous with rat V₁- or V₂-receptors, but within humans or rats the V₁-receptor is less than 50% homologous with the V₂-receptor. Furthermore, duplication of an ancestral gene is thought to have led to the co-presence in eutherian mammals of oxytocin and vasopressin, which have maintained a close structural similarity, yet in many species the oxytocin receptor is only 30 to 50% homologous with vasopressin receptors. Thus it appears that there has been greater evolutionary pressure to conserve the signal molecule, than to conserve the structure of the receptor. Evaluation of the evolution of neuropeptides and their receptors may be useful in determining phyletic relationships. Traditional classification places the guinea pig as a hystricomorph rodent within the same order (Rodentia) as the muriform or myomorph rat and mouse. However, molecular analyses of polypeptides have led to the suggestion that guinea pigs belong to a distinct order. Analysis of several neuropeptide sequences and the Y4 receptor supports this view. In general terms for both neuropeptides and receptors, sequence homology reflects phylogeny and taxonomy as based on morphological features. Within the oxytocin/vasopressin family in which peptides and receptors have been characterised in invertebrate representatives as well as fish and amphibia in addition to mammals, the molecular diversity correlates well with evolutionary diversity.     

Regional differences of the effect of σ receptor ligands on the acetylcholine release in the rat brain

Summary We found that a receptor ligands differentially regulated the acetylcholine (ACh) neurotransmission in the rat brain. Acute administration of (+)-N-allylnormetazocine [(+)-SKF-10,047], a prototype ₁ receptor ligand, and 1,3-di(2-tolyl)guanidine (DTG), a non-specific receptor ligand, increased the extracellular ACh level in the rat hippocampus. This increase of hippocampal extracellular ACh level elicited by (+)-SKF-10,047 was more potent than that elicited by DTG. On the other hand, the striatal extracellular ACh level was slightly affected by (+)-SKF-10,047. In addition, DTG did not affect the striatal extracellular ACh level. Our previous studies have shown that both (+)-SKF-10,047 and DTG increased the extracellular ACh level in the rat frontal cortex. Taking all these data into consideration, the regulation of ACh neurotransmission by receptor ligands are different depending upon the brain region.     

Correlation of interleukin-2 receptor and neopterin secretion in rheumatoid arthritis

Summary In rheumatoid arthritis (RA) an immuno dysregulation alters the release of neopterin from human monocytes/macrophages, probably by activation of a feed-back regulation mechanism in pterin metabolism. With the overactivation of T-lymphocytes, the secretion of interleukin-2 and its receptor (IL-2R) is influenced. Investigation on 84 RA patients has shown that this immunoactivation is accompanied by an increased secretion of neopterin and soluble IL-2R in the serum, and that both parameters are very suitable for detection of inflammatory disease activity. The significant correlation between neopterin and IL-2R (r=0.65; p0.001) in RA points out a possible connection in pathomechanisms of the immune system.     

20例原发性输卵管癌组织中ER、PR与p~(53)蛋白的表达

目的：分析原发性输卵管腺癌的ＥＲ、ＰＲ及ｐ５３蛋白的表达，研究其与该肿瘤的临床分期、病理分级及患者预后的关系。方法：材料选自２０份原发性输卵管腺癌及１０份正常输卵管组织的存档石蜡包埋标本，采用免疫组化法检测。结果：在２０份原发性输卵管癌标本中，ＥＲ、ＰＲ的阳性表达率分别为２５％和１５％，稍高于正常输卵管组的１０％，但差异无显著性（Ｐ＞０．０５）；ｐ５３蛋白在癌症组的阳性表达率为４０％，对照组则无１例阳性表达，差异有显著性（Ｐ＜０．０５）；ｐ５３蛋白在晚期、分化差及预后不良的输卵管癌病例中的表达呈上升趋势，但未达到统计学意义（Ｐ＞０．０５）；对侧输卵管炎症的存在与ｐ５３蛋白的阳性表达呈负相关（Ｐ＜０．０５）。结论：在原发性输卵管癌中，ＥＲ、ＰＲ有一定程度的表达，但均较低；ｐ５３基因的突变可能参与了该肿瘤的发生，并可作为综合判断其恶性程度及患者预后的指标之一。     

血管内皮生长因子及其受体对喉癌细胞生长的影响

为探讨血管内皮生长因子（ＶＥＧＦ）在喉癌中的作用及可能的作用方式，用抗ＶＥＧＦ抗体及其受体ｆｌｔ抗体通过微波处理暴露抗原后，进行标准化的ＥｌｉｔｅＡＢＣ染色；将不同浓度的抗ＶＥＧＦ及抗ｆｌｔ抗体分别加入ＨＥＰ－２细胞的培养液中，培养５ｄ后测ＨＥＰ－２细胞的活性（ＭＴＴ法）。结果：免疫组化染色显示ＶＥＧＦ及其受体ｆｌｔ主要在喉癌细胞和血管内皮细胞表达；不同浓度的ＶＥＧＦ抗体及抗ｆｌｔ抗体对ＨＥＰ－２