Acetylcholine (ACh) is a phylogenetically ancient molecule involved in cell-to-cell signaling in almost all life-forms on earth. Cholinergic components, including ACh, choline acetyltransferase, acetylcholinesterase, and muscarinic and nicotinic ACh receptors (mAChRs and nAChRs, respectively) have been identified in numerous non-neuronal cells and tissues, including keratinocytes, cancer cells, immune cells, urinary bladder, airway epithelial cells, vascular endothelial cells, and reproductive organs, among many others. Stimulation of the mAChRs and nAChRs elicits cell-specific functional and biochemical effects. These findings support the notion that non-neuronal cholinergic systems are expressed in certain cells and tissues and are involved in the regulation of their function and that cholinergic dysfunction is related to the pathophysiology of certain diseases. They also provide clues for development of drugs with novel mechanisms of action.

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Mucocutaneous keratinocytes and bronchial epithelial cells express nicotinic acetylcholine receptors (nAChRs). Emerging evidence indicates that nAChRs can be stimulated also by the tobacco-derived nitrosamines 4-(methylnitrosamino)-1-(3–pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) that can induce tumors in laboratory animals. Nitrosamines may disturb the delicate balance between cell proliferation, growth arrest, and apoptosis. A novel paradigm of cell regulation via nAChR has been discovered in studies of SLURP (secreted mammalian Ly-6/urokinase plasminogen activator receptor–related protein)-1 and -2. Experimental results suggest that SLURP-1 and -2 regulate keratinocyte proliferation, apoptosis, and differentiation. Most importantly, SLURPs and professional nicotinic antagonists can abolish, in part, the abilities of NNK and NNN to cause tumorigenic transformation of immortalized keratinocytes. Learning the pharmacology of the nitrosamine vs. SLURP action on epithelial cells may help develop an effective anti-cancer treatment and prevention programs wherein hazardous effects of tobacco products are anticipated, or even abolished, by a pharmacologic ligand of the specific nicotinic receptor acting as an antidote.

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Lung cancer is the leading cause of cancer death worldwide and new treatment strategies are clearly needed. The recent discovery that lung and other cancers synthesize and secrete acetylcholine (ACh) which acts as an autocrine growth factor suggests that this cholinergic autocrine loop may present new therapeutic targets. In normal bronchial epithelium, small airway epithelium and pulmonary neuroendocrine cells synthesize Ach; and in squamous cell lung carcinoma, adenocarcinoma, and small cell lung carcinoma, the respective lung cancers that derive from those cell types similarly synthesize ACh. ACh secreted by those cancers stimulates growth of the tumors by binding to nicotinic and muscarinic receptors expressed on lung cancers. Thus antagonists to nicotinic and muscarinic receptors can inhibit lung cancer growth. The muscarinic receptor (mAChR) subtype utilized for cell proliferation is the M₃ subtype and consistent with this M₃ mAChR antagonists inhibit growth of SCLC and squamous cell carcinomas. This is significant as M₃ mAChR antagonists have low toxicity and are in wide clinical use. As multiple other cancer types besides lung carcinomas express both M₃ mAChR and acetylcholine, other cancer types besides lung carcinoma may respond to M₃ mAChR antagonists.

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Lymphocytes possess all the components required to constitute an independent, non-neuronal cholinergic system. These include acetylcholine (ACh); choline acetyltransferase (ChAT), its synthesizing enzyme; and both muscarinic and nicotinic ACh receptors (mAChRs and nAChRs, respectively). ACh modifies T and B cell function via both mAChR- and nAChR-mediated pathways. Stimulation of lymphocytes with the T cell activator phytohemagglutinin, protein kinase C activator phorbol ester, or cell surface molecules enhances the synthesis and release of ACh and up-regulates ChAT and/or M₅ mAChR gene expression. Furthermore, animal models of immune disorders exhibit abnormal lymphocytic cholinergic activity. The cholesterol-lowering drug simvastatin attenuates the lymphocytic cholinergic activity of T cells by inhibiting LFA-1 signaling in a manner independent of its cholesterol-lowering activity. This suggests that simvastatin exerts its immunosuppressive effects in part by modifying lymphocytic cholinergic activity. Nicotine, an active ingredient of tobacco, ameliorates ulcerative colitis but exacerbates Crohn’s disease. Expression of mRNAs encoding the nAChR α7 and α5 subunits are significantly diminished in peripheral mononuclear leukocytes from smokers, as compared with those from nonsmokers. In addition, long-term exposure of lymphocytes to nicotine reduces intracellular Ca²⁺ signaling via α7 nAChR–mediated pathways. In fact, studies of humoral antibody production in M₁/M₅ mAChR–deficient and α7 nAChR–deficient animals revealed the role of lymphocytic cholinergic activity in the regulation of immune function. These results provide clues to understanding the mechanisms underlying immune system regulation and could serve as the basis for the development of new immunomodulatory drugs.

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Recently, several reports demonstrate that non-neuronal acetylcholine (ACh) release may contribute to various pathophysiological conditions. In this review, we presented our experiments designed to evaluate the non-neuronal cholinergic system in human bladder. After insertion of the microdialysis probe, human bladder strips were suspended in an organ bath filled with Krebs-Henseleit solution, and Ringer solution was perfused into the probe. ACh release was measured by microdialysis and HPLC. The contribution of urothelium and the effects of age and stretch of bladder strips on non-neuronal ACh release were evaluated. Choline acetyltransferase (ChAT) immunohistochemical staining of bladder was also performed. Immunohistochemistry showed marked ChAT-positive staining in the urothelium. There was tetrodotoxin-insensitive non-neuronal ACh release and this was significantly higher in strips with urothelium than in strips without urothelium. The non-neuronal ACh release was increased with age. Stretch of bladder strips caused increases in non-neuronal ACh release. The stretch-induced release of non-neuronal ACh was increased with age. Our data demonstrate that there is a non-neuronal cholinergic system in human bladder and that urothelium contributes to non-neuronal ACh release. There was significant age-related and stretch-induced increase in non-neuronal ACh release. It is suggested that the non-neuronal cholinergic system may contribute to the physiology and pathophysiology of human bladder. We also discussed the clinical significance of the non-neuronal cholinergic system in human bladder.

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The endogenous brain constituent, γ-hydroxybutyric acid (GHB), as well as its prodrug, γ-butyrolactone (GBL), have recently gained interest in the drug addiction field due to their abuse potential and fatalities caused by overdose. It is known that GHB has two sites of actions: the γ-aminobutyric acid_B (GABA_B) receptor and a specific-GHB binding site. The present study was designed to extend to GBL the investigations on the contribution of the GABA_B receptor and the specific-GHB binding site to its in vivo effects. To this aim, DBA mice were pretreated either with GABA_B-receptor antagonists, (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP 35348) and (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), or a putative antagonist of the specific-GHB binding site, 6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylideneacetic acid (NCS-382), prior to the administration of doses of GBL that induced hypothermia, motor-incoordination (measured as motor-impairment at the Rota-Rod task), and sedation/hypnosis. The capability of SCH 50911 and NCS-382 to protect against GBL-induced lethality was also investigated. Pretreatment with either GABA_B-receptor antagonist completely prevented GBL-induced hypothermia, motor-incoordination, and sedation /hypnosis. SCH 50911 also provided complete protection against GBL-associated lethality. Vice versa, NCS-382 failed to exert any antagonistic or protective effect. These results suggest that the in vivo GBL effects tested in the present study are mediated by activation of the GABA_B receptor.

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The role of mast cell mediators on cervical cancer cell migration was assessed using an in vitro assay of scratch wound healing onto monolayers of HPV18-positive cervical carcinoma cells (SW756). Migration of SW756 cells was accelerated by co-culture with the mast cell line LAD2. This effect was inhibited by the H1R antagonist pyrilamine and the cannabinoid agonists 2-arachidonylglycerol (2AG) and Win 55,212-2. Therefore, the specific effects of histamine and cannabinoids on SW756 migration and LAD2 activation were analyzed. Histamine added to the in vitro assay of scratch wound healing either increased or inhibited SW756 migration rate by acting either on H1R or H4R, respectively. Cannabinoids acted on CB1 receptors to inhibit SW756 migration. Supernatants from SW756 cells stimulated LAD2 cell degranulation, which in turn was inhibited by cannabinoids acting via CB2 receptors. RT-PCR showed that SW756 expressed mRNA for CB1, CB2, H1R, H2R, and H4R. On the other hand, LAD2 expressed mRNA for all four HRs and CB2. The results suggest that mast cells could be contributing to cervical cancer cell invasion and spreading by the release of histamine and cannabinoids. Therefore, therapeutic modulation of specific mast cell mediators may be beneficial for cervical cancer treatment.

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Previous studies have shown that cannabinoid 2 (CB₂)-receptor agonists might have analgesic effects on visceral hypersensitivity. To extend these results, we have determined the pharmacological characteristics of a newly designed CB₂ ligand, N-[(1S)-1-(aminocarbonyl)-2,2-dimethylpropyl]-3-(3-hydroxy-3-methylbutyl)-2-oxo-2,3-dihydro-1H-benzimidazole-1-carboxamide (PF-03550096), in vitro and in vivo. PF-03550096 showed high affinity to human (K_i = 7.9 ± 1.7 nM) and rat CB₂ receptors (K_i = 47 ± 5.6 nM). In a cell-based functional assay, PF-03550096 behaved as a full agonist and showed high selectivity for human CB₂ receptors. Orally administered PF-03550096 (3, 10 mg/kg) inhibited the 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced decrease in colonic pain threshold with statistical significance. The inhibitory effect of PF-03550096 (10 mg/kg) was significantly reversed by a selective CB₂ antagonist, N-(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl-5-(4-chloro-3-methylphenyl)-1(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528), while SR144528 itself did not modify colonic pain threshold. These results indicate that PF-03550096 is a potent CB₂ agonist and possesses efficacy in a rat model of visceral hypersensitivity.

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This study examined the effects of gomisin A, a lignan compound from Schisandra fructus, on D-galactosamine (GalN) and lipopolysaccharide (LPS)-induced hepatic apoptosis and liver failure. Mice were given an intraperitoneal injection of GalN (700 mg/kg) / LPS (10 μg/kg). Gomisin A (25, 50, 100, and 200 mg/kg) was administered intraperitoneally 1 h before the GalN/LPS injection. The liver injury was assessed biochemically and histologically. GalN/LPS increased the serum aminotransferase levels and lipid peroxidation but decreased the reduced glutathione level. The pretreatment with gomisin A attenuated these changes in a dose-dependent manner. The survival rate of the gomisin A group was significantly higher than that of the control. The mitochondria isolated after the mice had been injected with GalN/LPS were swollen, which was attenuated by the gomisin A pretreatment. The elevation of serum tumor necrosis factor-α and activation of caspase-3 were observed in the GalN/LPS group, which was attenuated by gomisin A. The gomisin A–pretreated groups showed significantly fewer apoptotic (TUNEL-positive) cells and DNA fragmentation as compared with the GalN/LPS mice. The liver protection afforded by gomisin A is the result of the reduced oxidative stress and its anti-apoptotic activity.

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Proanthocyanidins are condensed tannins present in fruits, vegetables, and flowers, consumed in the human diet. These compounds are believed to decrease coronary heart disease. The present study was designed to investigate the relaxing effects of a proanthocyanidin-rich fraction (PRF) obtained from Croton celtidifolius BAILL (Euphorbiaceae) barks in rat mesenteric arterial bed (MAB) and isolated mesenteric artery (MA). In the MAB pre-contracted with phenylephrine (Phe), PRF (0.1 – 100 μg) induced a concentration-dependent relaxation of 73% (compared to the control). This effect was significantly reduced by the nitric oxide (NO) synthase inhibitor N^ω-nitro-L-arginine (L-NOARG) or high K⁺ solution and completely abolished in vessels perfused with KCl plus L-NOARG. However, the vasorelaxant effect was not altered by indomethacin, atropine, yohimbine, pyrilamine, or K⁺-channel blockers: BaCl₂, glibenclamide, ouabain, and 4-aminopyridine. In isolated MA pre-contracted with Phe, PRF also induced a concentration-dependent relaxation (0.1 – 30 μg/mL), which was in turn inhibited by endothelial removal, guanylyl cyclase inhibitor 1H[1,2,3]oxadiazolo[4,3-alpha]quinoxalin, charybdotoxin (ChTx), and ChTx plus apamin. Moreover, the relaxant effect was not altered by HOE140 and apamin given alone. The present study demonstrates that the vasorelaxing effect of PRF is dependent upon the NO–cGMP pathway in combination with hyperpolarization due to activation of Ca²⁺-dependent K⁺ channels.

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We investigated the effects of prenatal dexamethasone (DEX) administration on antioxidant enzymes (AOEs) and nitric oxide synthase (NOS) in fetal and neonatal rat lungs. DEX (1 mg/kg, s.c., for 2 days) or vehicle alone was administered to pregnant rats, and the lungs of fetuses on days 19 and 21 of gestation and of 1- and 3-day-old neonates were examined. We measured protein levels of the AOEs manganese superoxide dismutase and copper-zinc superoxide dismutase (Mn SOD and Cu-Zn SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and inducible and endothelial nitric oxide synthase (i-NOS and e-NOS). Mn SOD, GSH-Px, and e-NOS expression gradually increased with increasing gestational and postnatal age in the lungs of the control groups. Cu-Zn SOD, CAT, and i-NOS expression did not change with increasing gestational and postnatal age in the lungs of the control groups. DEX administration had significant effects on i-NOS and e-NOS protein and mRNA expression. The increased Mn SOD, GSH-Px, and e-NOS expressions during the perinatal period suggests that antenatal developmental changes in AOEs in the lungs of premature fetuses could be reduced by reactive oxygen species–mediated injury at birth. Furthermore, antenatal glucocorticoid treatment may accelerate the development of lungs via the two types of NOS.

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A pain model for screening analgesics was established in anesthetized rats. The omenta of urethane-anesthetized rats were exteriorized, fixed in a plastic chamber, and superfused with Tyrode solution. Administration of bradykinin (BK) in the chamber elicited the reflex hypertensive response (RHR). Modification of the RHR was tested by topical (in the chamber) or intravenous administration of drugs. The BK dose-response curve was shifted to the right by topical indomethacin. The RHR by BK was inhibited by topical application of a BK B₂ antagonist, (Thi^5,8-D-Phe⁷-BK), a local anesthetic (2% carbocaine), and by intravenous administration of a ganglion blocker (hexamethonium) or an α-adrenergic blocker (dibenamine). The RHR by topical BK was almost completely inhibited by morphine and the suppression was largely reversed by naloxone. The RHR, induced by a threshold dose of BK and inhibited by indomethacin, was potentiated by pretreatment of the omentum with prostaglandin (PG) E₂ or PGI₂. PGE₂ was less potent, but the effect lasted longer than that of PGI₂. Topical administration of a non-acidic analgesic, mepirizole, inhibited the RHR by topical BK by only 20%, but intravenous mepirizole inhibited topical BK by 96.2%, indicating its major central action. This model may be useful for studying analgesics.

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We investigated whether endothelin (ET) would be involved in skin cancer pain in mice. Orthotopic inoculation of B16-BL6 melanoma cells into the plantar region of the hind paw produced marked mechanical allodynia in C57BL/6 mice. Intraplantar injections of the ET_A-receptor antagonist BQ-123 (0.3 – 3 nmol/site), but not the ET_B-receptor antagonist BQ-788 (1 and 3 nmol/site), inhibited mechanical allodynia in mice with grown melanoma. In naive mice, an intraplantar injection of tumor extract (1 and 3 mg/site), which was prepared from the grown melanoma in the paw, produced mechanical allodynia, which was inhibited by BQ-123 and BQ-788 at doses of 3 and 10 nmol/site. An intraplantar injection of ET-1 (1 and 10 pmol/site) elicited licking behavior, which was increased in the melanoma-bearing hind paw. BQ-123 (3 and 10 nmol/site) inhibited licking induced by ET-1 (10 pmol/site). The level of mRNA of ET_A, but not ET_B, receptor, was significantly increased in the dorsal root ganglia on the inoculated side. Cultured B16-BL6 cells contained ET, and the melanoma mass increased the concentration of ET as it grew bigger. These results suggest that ET-1 and ET_A receptor are at least partly involved in the induction of pain induced by melanoma cell inoculation.

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We examined the effect of ramosetron, a potent serotonin (5-HT)₃-receptor antagonist for irritable bowel syndrome with diarrhea, on conditioned fear stress (CFS)-induced defecation and normal (non-stressed) defecation in rats and compared ramosetron with the antidiarrheal agent loperamide and the spasmolytic agents trimebutine and tiquizium. Ramosetron, loperamide, trimebutine, and tiquizium significantly inhibited CFS-induced defecation in a dose-dependent manner with ED₅₀ (95% confidence limit) values of 0.019 (0.01 – 0.028), 9.4 (4.0 – 22), 850 (520 – 2,400), and 300 (190 – 450) mg/kg, respectively. A significant effect of ramosetron on CFS-induced defecation appeared at 10 min after dosing and was sustained for 8 h. In contrast, loperamide, trimebutine, and tiquizium significantly inhibited CFS-induced defecation between 1 – 8, 1 – 4, and 1 – 8 h after administration, respectively. High doses of ramosetron did not affect normal defecation, whereas loperamide, trimebutine, and tiquizium significantly inhibited this process. In conclusion, ramosetron has potent, rapid-onset, and long-lasting inhibitory effects on CFS-induced defecation in rats, but does not influence normal defecation. The present findings indicate that ramosetron will be a useful therapeutic agent for irritable bowel syndrome with diarrhea, showing greater efficacy and safety than other antidiarrheal and spasmolytic agents.

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Muscarinic receptors in the human and rat lower urinary tract (urinary bladder detrusor muscle and mucosa, and prostate) were identified by intact tissue segment binding assays with two radioligands, and the effects of prolonged receptor activation in vitro on muscarinic receptors were examined. Hydrophilic [³H]-NMS and hydrophobic [³H]-QNB bound to the detrusor muscle segments with the same density, suggesting that the muscarinic receptors were localized at the plasma membrane. While the density of muscarinic receptor was higher in detrusor muscle than in the bladder mucosa and prostate, there was no species-specific difference either in density or in subtype distribution (M₁, M₂, and M₃ subtypes in detrusor; M₂ and M₃ subtypes in bladder mucosa; and M₁ and M₂ subtypes in prostate). Incubation of detrusor strips with carbachol decreased [³H]-NMS binding sites within 20 min, followed by a reduction of [³H]-QNB binding sites after a 60-min lag phase. The loss of the binding sites over 3 h after carbachol treatment was the same (approximately 40%) for both radioligands. The present intact tissue segment binding assay reveals tissue-specific and plasma membrane distribution of distinct muscarinic receptor subtypes and their dynamic changes (internalization and down-regulation) in lower urinary tract of humans and rats.

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Although hypertension and vascular calcification are well established as important risk factors for several cardiovascular diseases, the relationship between them is unknown. Here, we investigated whether hypertension is relevant to vascular calcification by examining aortic smooth muscle cells (SMCs) isolated from the descending thoracic aortas of Wistar Kyoto rats (WKY) as normotensive rats and spontaneously hypertensive rats (SHR), a typical rat model of hypertension. Cells were cultured in DMEM containing 10% FBS for 6 days after reaching confluence. Von Kossa staining revealed that the positively stained calcified area of aortic SMCs from SHR increased rapidly compared to that from WKY. The gene expressions of calcification-regulating proteins including msh homeobox homolog 2, Osterix (a master transcription factor for osteogenesis), and alkaline phosphatase (ALP) (a marker of vascular calcification) were significantly increased in aortic SMCs from SHR compared to SMCs from WKY. On the other hand, Runx2, another osteogenic transcription factor, did not upregulate. Furthermore, we confirmed that ALP activity was strongly increased in aortic SMCs from SHR compared to SMCs from WKY. These results suggest that aortic SMCs from SHR tend to become easily calcified via an Msx2-Osterix signaling pathway.

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Caveolin-1 is a principal component of caveolae, invaginations of the plasma membrane that are enriched in cholesterol and sphingolipids. The expression of caveolin-1 has been shown to be tightly correlated to the progression of breast cancer tumors. However, the consequences of altered caveolin-1 expression during tumor progression still remain unclear. Modification of caveolin-1 expression modulates store-operated Ca²⁺ entry (SOCE) in various cell types. SOCE is a ubiquitous Ca²⁺ entry pathway that previous studies have linked to apoptosis and tumor progression in prostate cancer cells. In this study, we tested the effect of altering caveolin-1 expression on SOCE in Hs578/T breast cancer cells. Through overexpression of caveolin-1 and small hairpin RNA (shRNA) knockdown, we generated four stable cell lines that have 3 different caveolin-1 protein levels. Cav-1 overexpression could increase SOCE activity, while knockdown of caveolin-1 significantly reduced SOCE activity. These functional consequences were correlated with changes in caveolae number in Hs578/T cells. Our results suggest alteration of SOCE by caveolin-1 expression changes could be one of the mechanisms contributing to the progression of breast cancer.

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Previous in vitro studies have shown that the degradation of [Leu⁵]enkephalin during incubation with cerebral membrane preparations is almost completely prevented by a mixture of three peptidase inhibitors: amastatin, captopril, and phosphoramidon. The present in vivo study shows that the inhibitory effect of [Leu⁵]enkephalin administered intra-third-ventricularly on the tail-flick response was increased more than 500-fold by the intra-third-ventricular pretreatment with the three peptidase inhibitors. The antinociceptive effect produced by the [Leu⁵]enkephalin in rats pretreated with any combination of two peptidase inhibitors was significantly smaller than that in rats pretreated with the three peptidase inhibitors, indicating that any residual single peptidase could inactivate significant amounts of the [Leu⁵]enkephalin. The present data, together with those obtained from previous studies, clearly demonstrate that amastatin-, captopril-, and phosphoramidon-sensitive enzymes play important roles in the inactivation of short endogenous opioid peptides, such as penta-, hepta-, and octa-peptides, administered intra-third-ventricularly to rats.

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The posterior part of the hypothalamus plays a vital role in the homeostatic processes of the internal environment, including blood pressure and heart rate regulation, by means of γ-aminobutyric acid (GABA)ergic and glutamatergic neurotransmission. In this study we measured the extracellular levels of GABA and L-glutamic acid in the dorsomedial hypothalamic nucleus (DMH) and posterior hypothalamus (PH), following intracerebroventricular (i.c.v.) administration of bicuculline, a GABA_A-receptor antagonist, in genetic absence epileptic rats from Strasbourg (GAERS), where heart rate, blood pressure, and EEG recordings were also collected simultaneously. The i.c.v. injection of bicuculline (0.3 nmol) produced no response in non-epileptic Wistar rats but caused an increase in mean arterial pressure in GAERS (P<0.01). Microdialysis experiments showed that L-glutamic acid increased in the DMH in GAERS after bicuculline administration (P<0.01). Additionally, extracellular GABA concentration decreased in the PH (P<0.05). Bicuculline suppressed the spike-and-wave discharges, the characteristic sign of absence seizures. All these results suggest that the bicuculline-induced blood pressure response is accompanied by changes in L-glutamic acid levels in the DMH and GABA levels in the PH, indicating a bicuculline hypersensitivity in the DMH and PH of GAERS that may make the GAERS display an altered mode of central cardiovascular regulation. These results suggest that the circuits affected in GAERS are not only restricted to the regions responsible for seizure generation but also present in the hypothalamus.

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Inhibitors of PDE4 (cAMP-specific phosphodiesterase) induce side effects, including nausea and emesis, that limit their therapeutic potential. We investigated the function of two catalytically active conformations of PDE4 (a low-affinity conformer detected by conventional cAMP hydrolytic activity and a high-affinity conformer detected by [³H]rolipram binding) in neuronal cells. We assessed enhancement of β-adrenoceptor-mediated cAMP accumulation in cortical neurons in vitro by eleven PDE4 inhibitors with diverse biochemical profiles. The compounds tested have a wide inhibition range of PDE4 catalytic activity and [³H]rolipram binding. Inhibition potency for PDE4 catalytic activity and [³H]rolipram binding for each compound was different. Potency in augmentation of cAMP correlated significantly with the inhibitory effect on [³H]rolipram binding, but not with that against PDE4 catalytic activity. On the other hand, the inhibitory effect on proliferation of T-lymphocytes of the same PDE4 inhibitors correlated both with inhibition of PDE4 catalytic activity and with inhibition of [³H]rolipram binding. These findings indicate that the high affinity PDE4 conformer exists at a high level in cortical neurons and is important in the regulation of cAMP. Furthermore, the relative contributions of the two PDE4 conformers in cell function may cause different PDE4 inhibitor effects on cortical neurons and T-lymphocytes.

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Parthenolide is a sesquiterpene lactone that has been isolated from Tanacetum parthenium (feverfew). Parthenolide has several biological activities including the induction of apoptosis and inhibition of NF-κB. Because of its activities against several tumor types and because it is relatively well tolerated, in clinical trial, parthenolide is an attractive compound for the treatment of brain tumors. However, there have been no reports concerning its ability to induce apoptosis in any brain tumor cell lines. In this report we demonstrate that treatment of glioblastoma cells with parthenolide resulted in rapid apoptosis through caspase 3/7 without a suppression of NF-κB activity.

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To investigate the role of tissue plasminogen activator (tPA) in methamphetamine (METH)-induced dopaminergic neurotoxicity, we compared the changes in tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels in the striatum after repetitive treatment of METH at 4 mg/kg among wild-type, tPA-deficient (tPA−/−), and protease activated receptor-1–deficient (PAR-1−/−) mice. METH treatment caused a marked decrease in TH and DAT levels in the striatum of those mice with a similar magnitude. No difference in METH-induced abnormal behavior and hyperthermia was observed among the three types of mice. These results suggest that neither tPA nor PAR-1 is involved in METH-induced dopaminergic neurotoxicity in vivo.

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