The cyclooxygenase-2/prostaglandin E2 pathway is involved in the somatostatin-induced decrease of epileptiform bursting in the mouse hippocampus

The neuromodulatory peptide somatostatin-14 (SRIF) plays an important inhibitory role in epilepsy, but little is known on the signalling mechanisms coupled to this effect of SRIF. We have previously demonstrated that SRIF induces reduction of epileptiform bursting in a model of interictal-like activity in mouse hippocampal slices. In this same model, we investigated whether the cyclooxygenase 2 (COX-2)/prostaglandin E(2) (PGE(2)) pathway is part of those signalling mechanisms mediating SRIF anti-epileptic actions. Both the expression of COX-2 (mRNA and protein) and the endogenous release of PGE(2) increased in concomitance with epileptiform bursting. In particular, COX-2 protein increased in CA1/CA3 pyramidal layer and in the granular layer of the dentate gyrus. In addition, the selective inhibition of COX-2 by NS-398 markedly decreased endogenous PGE(2) release induced by epileptiform bursting and the epileptiform bursting itself. Similar effects on epileptiform bursting were obtained with another COX-2 inhibitor, i.e., meloxicam. SRIF application counteracted the increase of both COX-2 expression and PGE(2) release which occurred in concomitance with epileptiform bursting. Interestingly, SRIF and NS-398 comparably reduced epileptiform bursting in a non-additive manner and PGE(2) abolished the inhibitory effect of SRIF on epileptiform bursting. These results demonstrate that: i) the COX-2/PGE(2) pathway facilitates epileptiform bursting; and ii) SRIF exerts an anti-epileptic role by coupling to the COX-2/PGE(2) pathway. In conclusion, we have identified a key set of signalling events that underlie anti-convulsant effects of SRIF in a mouse model of hippocampal bursting, thus providing useful data not only to identify alternative intervention points for the modulation of SRIF function, but also to exploit new chemical space for drug-like molecules.     

1-Ethyl-2-benzimidazolinone (EBIO) suppresses epileptiform activity in in vitro hippocampus

Ca2+-activated K+ currents with medium (mI(AHP)) and slow (sI(AHP)) kinetics, that mediate the post-spike medium and slow after-hyperpolarization (AHP), respectively, play critical roles in regulating neuronal excitability and the spread of epileptiform activity and could provide new therapeutic targets for the management of epileptic patients. We tested if the enhancement of the mI(AHP) by 1-ethyl-2-benzimidazolinone (EBIO) could suppress epileptiform activity in two in vitro models of epileptogenesis induced in CA3 hippocampal pyramidal neurons by superfusion with 4-AP- and kainate-Mg2+-free solutions. Both interictal- and ictal-like epileptiform activities were reversibly suppressed by EBIO concentrations between 200 microM and 1 mM. EBIO predominantly acted by a strong reduction of excitability via an increase (approximately 450%) of the mI(AHP), without changing the sI(AHP). Glutamatergic excitatory synaptic transmission was also diminished (approximately 50%) by 1 mM EBIO. In contrast, EBIO concentrations <400 microM had no effect on synaptic excitation, consistent with a lesser sensitivity to the drug than the mI(AHP). Apamine (100 nM), a toxin that specifically inhibits the mI(AHP), rapidly and reversibly antagonized the blocking effects of EBIO on epileptiform activity. Our results suggest that manipulations that enhance the mI(AHP) may prove adequate in the treatment of epilepsies; they also suggest that an abnormal down regulation of the mI(AHP) may be a key factor in the genesis of hyperexcitable states.     

Involvement of spinal PKA/CREB signaling pathway in the development of bone cancer pain

BackgroundIt has been shown that spinal PKA/CREB signaling pathway is involved in neuropathic and inflammatory pain, but its effects on bone cancer pain have not previously been investigated. The aim of this study was to examine the potential role of the spinal PKA/CREB signaling pathway in the development of bone cancer pain.MethodsAbone cancer pain model was made by inoculation of Walker 256 cells into the intramedullary space of rat tibia.Western blot analysis examined the expression of PKAca (PKA catalytic subunit) and phospho-CREB (p-CREB) protein levels. The authors further investigated effects of intrathecal treatment with H-89 (a PKA inhibitor, 8 nmol) or forskolin (a PKA agonist, 10 nmol) on nociceptive behavior and the expression of PKAca and p-CREB.ResultsOn days 6, 9, and 15 after inoculation, the expression of PKAca and p-CREB protein levels were higher in the bone cancer pain rats compared to the sham rats. On day 9, intrathecal administration of H-89 significantly attenuated bone cancer-induced mechanical allodynia as well as upregulation of PKAca and p-CREB protein levels. These effects were completely abolished by intrathecal pretreatment with the PKA agonist forskolin.ConclusionThe results suggest that the spinal PKA/CREB signaling pathway may participate in the development of bone cancer pain. The findings of this study may provide an evidence for developing novel analgesics to block bone cancer pain.     

BDNF-TrkB signaling pathway mediates the induction of epileptiform activity induced by a convulsant drug cyclothiazide

Brain-derived neurotrophic factor (BDNF) and its receptor TrkB play an important function in neuronal development and synaptic plasticity. Recently we have established that cyclothiazide (CTZ) is a novel convulsant drug inducing robust epileptiform activity in hippocampal neurons both in vitro and in vivo. However, the molecular mechanisms underlying such convulsant action of CTZ are unknown. Here, we investigated potential roles of BDNF-TrkB signaling pathway in the CTZ-induction of epileptiform activity. In anaesthetized rats, CTZ dose-dependently induced epileptiform activity characterized by progressing of multiple peaks of population spikes, spontaneous spiking events, and synchronized epileptiform bursts. Pre-injection of a receptor tyrosine kinase inhibitor K252a or a specific antibody for TrkB receptors before intracerebroventricular injection of CTZ significantly suppressed the epileptiform activity induced by CTZ. Similarly, in cultured hippocampal pyramidal neurons, pre-treatment with CTZ together with K252a or TrkB-receptor antibody also inhibited the CTZ-induction of epileptiform activity. Furthermore, we demonstrated that acute application of K252a in hippocampal cultures inhibited epileptiform bursts and action potential firing. We conclude that activation of BDNF-TrkB signaling pathway is fundamentally important during the CTZ-induction of epileptiform activity both in vitro and in vivo.     

Group I mGluRs modulate the pattern of non-synaptic epileptiform activity in the hippocampus

The hippocampus is well known for its susceptibility to epileptic seizures, in part because of its neuronal architecture that facilitates synchronization. Although synaptic networks are important for the genesis and spread of epileptiform activity, synchronization of neuronal activity can occur when action potential-dependent chemical synaptic transmission is absent. In particular, it is possible to induce epileptiform activity by perfusing hippocampal slices with a low-Ca(2+)/high-K(+) mediums. Using extracellular recording in area CA1 we have characterized the effects of metabotropic glutamate receptor (mGluR) activation on this non-synaptic bursting activity. Under control conditions, bursting occurred at intervals of 14-86 s with each burst comprising a long (up to 44 s) negative-going field potential of 2 to 13 mV superimposed upon which was sustained firing of population spikes. Activation of group I mGluRs by (S)-3,5-dihydroxyphenylglycine (DHPG) (25 microM) caused a dramatic increase in burst frequency (up to five-fold), which was accompanied by a decrease in the duration and amplitude of bursts. The selective mGluR(1) antagonist 2-methyl-4-carboxyphenylglycine (LY367385) and the selective mGluR(5) antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) both restricted the increase in burst frequency induced by DHPG. However, only LY367385 inhibited the decrease in burst duration and amplitude. Combined application of both antagonists prevented all DHPG-induced changes in bursting activity. These data provide evidence for a role of both mGluR(1) and mGluR(5) subtypes in changing the frequency of non-synaptic bursting, with mGluR(1) alone causing alterations in burst duration and amplitude. These effects are likely to contribute to the group I mGluR-induced changes in synaptic epileptic activity that are already well documented.     

Model-specific effects of bumetanide on epileptiform activity in the in-vitro intact hippocampus of the newborn mouse

The immature brain has a higher susceptibility to develop seizures, which often respond poorly to classical pharmacological treatment. It has been recently suggested that bumetanide, which blocks Na(+)-dependent K(+)-Cl(-)-cotransporter isoform 1 (NKCC1) and thus attenuates depolarizing GABAergic responses, could soothe epileptiform activity in immature nervous systems. To evaluate whether bumetanide consistently attenuates epileptiform activity, we investigated the effect of 10 microM bumetanide in five different in-vitro epilepsy models using field potential recordings in the CA3 region of intact mouse hippocampal preparations at postnatal day 4-7. Bumetanide reduced amplitude and frequency of ictal-like events (ILE) induced by 8.5 mM K(+), but it increased the frequency of ILE induced by 1 microM kainate. Inhibition of ligand-gated Cl(-) channels by 10 microM gabazine and 30 microM strychnine induced interictal activity (IA) that was only marginally affected by bumetanide. Removal of extracellular Mg(2+) induced both ILE and IA. Bumetanide had no effect on these ILE but enhanced the IA. Low-Mg(2+) solution containing 20 microM 4-AP induced late-recurrent discharges, which were slightly attenuated by bumetanide. In summary, our results demonstrate that bumetanide exerts diverse effects in different in-vitro epilepsy models.     

天麻素调节癫疒间大鼠海马炎症信号通路的抗癫疒间机制研究

目的探讨天麻素调节戊四氮(PTZ)致癫疒间大鼠海马炎症信号通路的抗癫疒间机制。方法将40只成年Wistar大鼠随机分为正常对照组(NC)、癫疒间模型组(PTZ)、天麻素大剂量组(Gh)和天麻素小剂量组(Gs),观察四组大鼠的行为学和脑电图的变化,应用Western blot检测p38MAPK蛋白表达,ELISA方法测定大鼠海马IL-1β、IL-2、IL-6和肿瘤坏死因子(TNF-α)的含量。结果与PTZ组相比,Gh组大鼠癫疒间发作程度、脑电图改变、海马p38MAPK蛋白的表达和部分炎性细胞因子IL-1β、IL-2、IL-6和TNF-α的含量明显减少(P<0.01)。结论天麻素可通过降低癫疒间大鼠海马p38MAPK蛋白的表达、抑制部分炎性细胞因子IL-1β、IL-2、IL-6和TNF-α的分泌,从而影响炎症信号通路,以达到对抗癫疒间的效果。     

TrkB不同亚型对癫痫海马神经元BDNF/TrkB信号通路调控的研究

目的 脑源性神经营养因子(BDNF)及其酪氨酸激酶B受体（TrkB）与癫痫关系密切,该研究探讨了癫痫神经元中TrkB不同亚型对BDNF/TrkB信号通路的调控。 方法 将14组海马神经元细胞分为钙调蛋白抑制剂（N-Acetyl-L-leucyl-L-leucyl-L-norleucinal,ALLN）组和翻译抑制剂（Anisomycin）组。免疫荧光鉴定海马神经元,无镁液处理制备癫痫模型,电生理鉴定细胞痫样放电,免疫印迹技术检测癫痫模型中TrkB和磷酸化TrkB（p-TrkB）蛋白的表达变化。 结果 细胞培养至第7天时,神经元形态特征明显,形成明显的神经网络,纯度60%-70%。经无镁细胞外液处理3小时后再恢复到正常细胞外液,电生理检测到神经元持续强直高频爆发的“癫痫样”自发性放电。免疫印迹结果显示：1. 正常+BDNF组高于正常组;2. 癫痫+BDNF组高于癫痫组,低于正常+BDNF组;3. 癫痫+ALLN+BDNF组低于癫痫+BDNF组;4. 癫痫+ALLN+BDNF组和癫痫+ALLN组差异无统计学意义;5. 癫痫+Anisomycin+BDNF组高于癫痫+BDNF组和癫痫+Anisomycin组。 结论 BDNF可激活BDNF/TrkB信号通路。癫痫状态下BDNF/TrkB通路处于抑制状态,TrkB.T的上调引起BDNF/TrkB通路的抑制,TrkB.FL表达变化不能活化BDNF/TrkB通路。     

Oral administration of docosahexaenoic acid activates the GDNF-MAPK-CERB pathway in hippocampus of natural aged rat

Abstract

Context: Docosahexaenoic acid (DHA) is one of the critical fatty acids for optimal health, which affect the expression of nerve growth factor and brain-derived neurotrophic factor in brain.

Objective: This study investigates whether DHA supplementation affects lipid peroxidation and activates the glial-derived neurotrophic factor (GDNF)-mitogen-activated protein kinase pathway (MAPK pathway) in hippocampus of natural aged rat.

Materials and methods: Rats were randomly divided into four groups; DHA was orally administered at 80 and 160?mg/kg/day to 24-month female rats for 50 days. The antioxidant parameters and GDNF-GDNF family receptor α-1 (GFRα1)-tyrosine-protein kinase receptor (RET)-MAPK-cyclic AMP response element-binding protein (CERB) pathway were assayed in natural aged rat’s hippocampus.

Results and discussion: The results demonstrated that DHA supplementation significantly increased the activities of superoxide dismutase (SOD) by 37.39 and 57.69%, glutathione peroxidase (GSH-Px) by 27.62 and 32.57% decreased TBARS level by 28.49 and 49.05%, respectively, but did not significantly affect catalase (CAT), in hippocampus, when compared with the aged group. DHA supplementation in diet resulted in an increase of DHA level in hippocampus. Furthermore, we found that DHA supplementation markedly increased the levels of GDNF and GFRα1 and the phosphorylation of RET, and led to the activation of the MAPK pathway in hippocampus tissue.

Conclusion: DHA supplementation can change fatty acids composition, improve antioxidant parameters and activate the GDNF-MAPK pathway in natural aged rat’s hippocampus.     

CB1 receptor-dependent and -independent inhibition of excitatory postsynaptic currents in the hippocampus by WIN 55,212-2

We investigated the effect of a synthetic cannabinoid, WIN 55,212-2 on excitatory postsynaptic currents (EPSCs) evoked by stimulation of Schaffer collaterals in CA1 pyramidal cells. Bath application of WIN 55,212-2 reduced the amplitude of EPSCs in dose-dependent manner tested between 0.01 nM and 30 microM. In rats and mice, this cannabinoid ligand inhibited excitatory synapses in two steps at the nM and muM concentrations. When the function of CB(1) cannabinoid receptors (CB(1)R) was impaired, either by the application of a CB(1)R antagonist AM251, or by using CB(1)R knockout mice, WIN 55,212-2 in microM concentrations could still significantly reduced the amplitude of EPSCs. WIN 55,212-2 likely affected the efficacy of excitatory transmission only at presynaptic sites, since both at low and high doses the paired pulse ratio of EPSC amplitude was significantly increased. The inactive enantiomer, WIN 55,212-3, mimicked the effect of WIN 55,212-2 applied in high doses. In further experiments we found that the CB(1)R-independent effect of 10 microM WIN 55,212-2 at glutamatergic synapses was fully abolished, when slices were pre-treated with omega-conotoxin GVIA, but not with omega-agatoxin IVA. These data suggest that, in the hippocampus, WIN 55,212-2 reduces glutamate release from Schaffer collaterals solely via CB(1)Rs in the nM concentration range, whereas in microM concentrations, WIN 55,212-2 suppresses excitatory transmission, in addition to activation of CB(1)Rs, by directly blocking N-type voltage-gated Ca(2+) channels independent of CB(1)Rs.     

Involvement of the extracellular signal regulated kinase pathway in hydrocarbon-induced reactive oxygen species formation in human neutrophil granulocytes

In the present study we have examined the effects of hydrocarbons on the formation of reactive oxygen species (ROS) in human neutrophil granulocytes in vitro. We found that hydrocarbons induce ROS formation in a concentration-dependent manner and that the ROS-inducing potency increases with increasing number of carbon atoms in the structure. In general, aromatic hydrocarbons were less potent inducers of ROS than aliphatic and cyclic hydrocarbons. The most potent compound in each group, t-butylcyclohexane, n-decane, and n-butylbenzene, were chosen for mechanistic studies. ROS formation was inhibited by the MEK1/2 inhibitor U0126, the tyrosine kinase inhibitor erbstatin-A, and the phosphatidylinositol-3 kinase inhibitor wortmannin. The involvement of the ERK1/2 pathway was confirmed by Western blot analysis of phosphorylated ERK1/2. The study revealed only small differences in the mechanisms involved for the three compounds. The responses were not affected by Pertussis toxin, indicating that Gi-protein coupled receptors are not involved in neutrophil activation after hydrocarbon exposure. Based on these findings we propose a mechanism involving tyrosine kinases, PI3 kinase, and the ERK1/2 pathway, leading to activation of the NADPH oxidase and production of ROS in neutrophils stimulated by organic solvents.     

托吡酯对青霉素诱发大鼠痫性放电和海马区相关递质含量的影响

目的　观察托吡酯对大鼠皮层定位注射青霉素诱发惊厥模型的对抗作用,并探讨其作用机制。方法　建立大鼠皮层定位注射青霉素诱发惊厥模型,观察两种剂量托吡酯ig给药对青霉素诱发痫性发作的程度和海马区痫性放电的潜伏期、痫波发放频率及痫波最高波幅的影响;采用HPLC法测定惊厥大鼠海马区Glu、Asp、Gly、GABA含量的变化。结果　两种剂量托吡酯(110, 440mg·kg-1,ig)均可减轻大鼠惊厥发作的程度,延长痫性放电的潜伏期,减少痫波发放频率,减小放电最高波幅,与模型组比较,差异均具有显著性(P<0 05或P<0 01)。同时,均可使大鼠海马区Glu含量降低,GABA含量升高,与模型组比较差异均有显著性 (P<0 05或P<0 01)。结论　托吡酯可明显抑制皮层定位注射青霉素诱发的痫性发作和痫性放电, 产生抗惊厥作用。其作用机制可能与加强GABA抑制功能和限制Glu兴奋功能有关。     

Modulation of the firing activity of noradrenergic neurones in the rat locus coeruleus by the 5-hydroxtryptamine system

1. The aim of the present study was to investigate the putative modulation of locus coeruleus (LC) noradrenergic (NA) neurones by the 5-hydroxytryptaminergic (5-HT) system by use of in vivo extracellular unitary recordings and microiontophoresis in anaesthetized rats. To this end, the potent and selective 5-HT_1A receptor antagonist WAY 100635 (N-{2-[4(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl)cyclohexanecarboxamide trihydroxychloride) was used.
2. In the dorsal hippocampus, both local (by microiontophoresis, 20 nA) and systemic (100 μg kg⁻¹, i.v.) administration of WAY 100635 antagonized the suppressant effect of microiontophorectically-applied 5-HT on the firing activity of CA₃ pyramidal neurones, indicating its antagonistic effect on postsynaptic 5-HT_1A receptors.
3. WAY 100635 and 5-HT failed to modify the spontaneous firing activity of LC NA neurones when applied by microiontophoresis. However, the intravenous injection of WAY 100635 (100 μg kg⁻¹) readily suppressed the spontaneous firing activity of LC NA neurones.
4. The lesion of 5-HT neurones with the neurotoxin 5,7-dihydroxytryptamine increased the spontaneous firing activity of LC NA neurones and abolished the suppressant effect of WAY 100635 on the firing activity of LC NA neurones.
5. In order to determine the nature of the 5-HT receptor subtypes mediating the suppressant effect of WAY 100635 on NA neurone firing activity, several 5-HT receptor antagonists were used. The selective 5-HT₃ receptor antagonist BRL 46470A (10 and 100 μg kg⁻¹, i.v.), the 5-HT_1D receptor antagonist GR 127935 (100 μg kg⁻¹, i.v.) and the 5-HT_1A/1B receptor antagonist (−)-pindolol (15 mg kg⁻¹, i.p.) did not prevent the suppressant effect of WAY 100635 on the firing activity of LC NA neurones. However, the suppressant effect of WAY 100635 was prevented by the non-selective 5-HT receptor antagonists spiperone (1 mg kg⁻¹, i.v.) and metergoline (1 mg kg⁻¹, i.v.), by the 5-HT₂ receptor antagonist ritanserin (500 μg kg⁻¹, i.v.). It was also prevented by the 5-HT_1A receptor/α_1D-adrenoceptor antagonist BMY 7378 (1 mg kg⁻¹, i.v.) and by the α₁-adrenoceptor antagonist prazosin (100 μg kg⁻¹, i.v.).
6. These data support the notion that the 5-HT system tonically modulates NA neurotransmission since the lesion of 5-HT neurones enhanced the LC NA neurones firing activity and the suppressant effect of WAY 100635 on the firing activity of NA neurones was abolished by this lesion. However, the location of the 5-HT_1A receptors involved in this complex circuitry remains to be elucidated. It is concluded that the suppressant effect of WAY 100635 on the firing activity of LC NA neurones is due to an enhancement of the function of 5-HT neurones via a presynaptic 5-HT_1A receptor. In contrast, the postsynaptic 5-HT receptor mediating this effect of WAY 100635 on NA neurones appears to be of the 5-HT_2A subtype.

     

Ghrelin-induced activation of cAMP signal transduction and its negative regulation by endocannabinoids in the hippocampus

Increasing evidence indicates that the gut peptide ghrelin facilitates learning behavior and memory tasks. The present study demonstrates a cellular signaling mechanism of ghrelin in the hippocampus. Ghrelin stimulated CREB (cAMP response-element binding protein) through the activation of cAMP, protein kinase A (PKA), and PKA-dependent phosphorylation of NR1 subunit of the NMDA receptor. Ghrelin increased phalloidin-binding to F-actin suggesting CREB-induced gene expression might include reorganization of cytoskeletal proteins. The effect was blocked by the antagonist of the ghrelin receptor in spite of the receptor’s primary coupling to Gq proteins. We also discovered inhibitory effect of endocannabinoids on ghrelin-induced NR1 phosphorylation and CREB activity. 2-arachidonoylglycerol (2-AG) exerted its inhibitory effect in the Type 1 cannabinoid receptor (CB1R)-dependent manner, while anandamide’s inhibitory effect persisted in the presence of antagonists of CB1R and the vanilloid receptor, suggesting that anandamide might directly inhibit NMDA receptor/channels. Our findings may explain how ghrelin and endocannabinoids regulate hippocampal appetitive learning and plasticity.     

Effects of the triazole derivative loreclezole (R72063) on stimulus induced ionic and field potential responses and on different patterns of epileptiform activity induced by low magnesium in rat entorhinal cortex-hippocampal slices

Summary Effects of loreclezole (R72063), a triazole derivative with anticonvulsant properties, were studied on field potentials in rat hippocampal slices and on different patterns of low Mg²⁺-induced epileptiform activity in combined entorhinal cortex-hippocampal slices. Lowering extracellular Mg²⁺ induced recurrent (10–60/min), short (40 – 80 ms) discharges in hippocampal areas CA1 and CA3. In the entorhinal cortex (EC) up to 90 s long ictaform events associated with large negative field potential and changes in the neuronal microenvironment were generated. These seizure like events changed their characteristics after one to two hours to recurrent discharges of 0.8 to 10 s. 20 M loreclezole blocked the seizure like events in the entorhinal cortex completely 30–80 min after onset of application. The recurrent short discharges in the hippocampus were reliably blocked by 40 M loreclezole 60 – 90 min after bath application with incomplete recovery after washout of several hours. The recurrent discharges in the entorhinal cortex were reliably blocked by 80 M loreclezole applied for 80–100 min. Decreases in [Ca²⁺]₀ and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum were depressed in a dose dependent manner, while similar changes induced by alvear stimulation remained almost unaffected. A paired pulse stimulus paradigm used to test for effect of loreclezole on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the response to a paired pulse stimulus to stratum radiatum was depressed over the whole range of tested stimulus intervals (15 to 150 ms). The findings suggest that loreclezole has effects on different patterns of epileptiform activity induced by extracellular low Mg²⁺ possibly by interfering with processes leading to frequency potentiation. Correspondence to: C. L. Zhang at the above address     

Involvement of the peroxisome proliferator-activated receptor alpha in the immunomodulation caused by peroxisome proliferators in mice

Peroxisome proliferators (PPs) are a large class of structurally diverse chemicals, which includes drugs designed to improve the metabolic abnormalities linking hypertriglyceridemia to diabetes, hyperglycemia, insulin-resistance and atherosclerosis. We have recently demonstrated that exposure of rodents to potent PPs indirectly causes a number of immunomodulating effects, resulting in severe adaptive immunosuppression. Since the peroxisome proliferator-activated receptor alpha (PPARalpha) plays a central role in mediating the pleiotropic responses exerted by PPs, we have compared here the immunomodulating effects of the PPs perfluorooctanoic acid (PFOA) and Wy-14,643 in wild-type and PPARalpha-null mice. The reductions in spleen weight and in the number of splenocytes caused by PP treatment in wild-type mice was not observed in PPARalpha-null mice. Furthermore, the reductions in thymus weight and in the number of thymocytes were potently attenuated in the latter animals. Similarly, the dramatic decreases in the size of the CD4(+)CD8(+) population of cells in the thymus and in the number of thymocytes in the S and G2/M phases of the cell cycle observed in wild-type mice administered PPs were much less extensive in PPARalpha-null mice. Finally, in contrast to the case of wild-type animals, the response of splenocytes isolated from the spleen of PP-treated PPARalpha-null mice to appropriate T- or B-cell activators in vitro was not reduced. Altogether, these data indicate that PPARalpha plays a major role in the immunomodulation caused by PPs. The possible relevance of these changes to the alterations in plasma lipids also caused by PPs is discussed.     

生长抑素在胃肠道肿瘤所致恶性肠梗阻非手术治疗中的疗效观察

目的：观察生长抑素在无法行手术治疗的恶性肠梗阻治疗中的临床疗效。方法60例恶性肠梗阻患者,随机分为常规治疗组（对照组）28例和生长抑素组（治疗组）32例,治疗组给予常规治疗加用生长抑素（6 mg/d持续静脉泵入）3~12 d。比较两组的近期临床疗效。结果治疗组临床症状较对照组明显改善,腹痛腹胀缓解率分别为81.25%、57.14%,差异有统计学意义（P〈0.05）;肛门恢复排便排气比率分别为71.88%、53.57%,差异有统计学意义（P〈0.05）,且治疗组恢复肛门排气时间（4.5±1.5）d,明显早于对照组（6.8±2.1）d（P〈0.05）;治疗组胃肠引流量明显少于对照组,分别为（256±152）ml/d、（489±198）ml/d,差异有统计学意义（P〈0.01）;腹部平片显示肠管积气积液减少消失,治疗组（84.38%）明显优于对照组（67.86%）（P〈0.05）;生活质量明显改善, KPS评分分别为（58±10）分、（41±9）分,两组比较差异有统计学意义（P〈0.01）。结论在常规治疗基础上联合生长抑素治疗恶性肠梗阻,能显著改善患者临床症状,提高生活质量。     

Changes in sodium, potassium-ATPase induced by repeated fencamfamine: the roles of cyclic AMP-dependent protein kinase and the nitric oxide-cyclic GMP pathway

Fencamfamine (FCF) is an indirect dopamine agent with effects similar to amphetamine and cocaine. In the present study, we investigate changes in Na,K-ATPase, cyclic AMP-dependent protein kinase (PKA) and nitric oxide synthase (NOS) activity and cyclic GMP levels in the nucleus accumbens (NAc) and striatum (ST) of animals acutely or repeatedly treated with FCF (3.5 mg/kg). Na,K-ATPase had a similar activity in control and repeatedly treated animals, but was reduced in the NAc of the acute group. This enzyme was reduced in the ST in acute and repeatedly treated animals, compared to the control group. Expression of the _1,2,3-Na,K-ATPase isoforms in the NAc and the ST was not altered in all groups studied. Acute FCF induced a significant increase in PKA activity in both the ST and the NAc. Repeatedly treated animals showed a higher increase in PKA activity in the NAc, but not in the ST, when compared to the acute group. There was also an increase in both NOS activity and cyclic GMP levels only in the NAc of FCF repeatedly treated animals compared to the acute and control groups. We suggest that chronic FCF treatment is linked to a modification in Na,K-ATPase activity through the PKA and NO–cyclic GMP pathway.     

Modulation of methotrexate-induced cytogenotoxicity in mouse spermatogonia and its transmission in the male germline by caffeine

Apart from its own controversial cytogenotoxic effects, caffeine (CAF), one of the most commonly consumed alkaloids worldwide, is found potentiative to and so also protective from the cytogenotoxic effects of numerous chemical and physical mutagens. It also has modulated the actions of several antineoplastic agents. Additionally, it has been tested as a chemopreventive of cancer and is reportedly associated inversely with different cancer risks. Therefore, in the present study, three different sub-lethal doses of CAF, 25, 50 and 100 mg/kg, were tested in mouse to assess their cytogenotoxic effects on dividing spermatogonia at 24 h post-treatment, and transmission of such effects in the male germline from the primary spermatocytes and sperm at week 4 and week 8 post-treatment, respectively. CAF was found to be weakly clastogenic to mouse spermatogonia and the effects were also found transmitted in the male germline. Interestingly, such induced effects were quantitatively related to the dose of CAF tested. On the other hand, methotrexate (MTX), an antifolate antimetabolite, is prescribed frequently for the treatment of various types of cancers. However, MTX is reportedly clastogenic. Modulation of the said three different pre-treated doses of CAF on MTX 10 mg/kg-induced cytogenotoxic effects, tested in the same experimental protocol, indicated that CAF pre-treatment was decreasing the MTX-induced clastogenicity in spermatogonia, and was lowering the concurrent transmission of such effects in the male germline of mice, significantly. Such decreases were related to the dose of CAF tested, i.e. higher the dose of CAF more was the decrease in the MTX-induced cytogenotoxic effects and in their transmission. The possible mechanisms that might have caused the manifestation of a weak clastogenic action of CAF on spermatogonia and in its transmission in the male germline, and the CAF modulation of MTX-induced cytogenotoxic effects in spermatogonia and in their transmission have been discussed.     

H2受体介导组胺对大鼠海马缺氧缺糖诱导细胞水肿及活性降低的保护作用

目的探讨组胺对海马脑片缺血诱导细胞水肿及活性降低的作用，以及与受体亚型的关系。方法大鼠海马脑片以缺氧缺糖(OGD)诱导缺血损伤后，实时检测CA1区透光度变化评价细胞水肿；并测定2,3,5-三苯基氯化四氮唑(TTC)产物甲，评价脑片活性。观察不同浓度组胺的作用，以及组胺受体拮抗剂对组胺作用的影响。结果 组胺(0.01～10 μmol·L^-1)明显抑制OGD诱导的海马脑片透光度增加，并提高脑片活性。H₁受体拮抗剂苯海拉明(0.1～10 μmol·L^-1)不影响组胺的作用，H₂受体拮抗剂西咪替丁(0.1～10 μmol·L^-1)则部分拮抗组胺的保护作用。结论组胺对大鼠海马脑片缺血诱导细胞水肿及活性降低有保护作用，该作用与H₂受体有关。