Novel regulatory systems for acetylcholine release in rat striatum and anti-Alzheimer's disease drugs.

Regulation of neurotransmitter release in the central nervous system is complex. Here, we investigated regulatory mechanisms for acetylcholine (ACh) release from cholinergic neurons by performing superfusion experiments with rat striatal segments after labelling the cellular ACh pool with [3 H]choline. Electrical stimulation-evoked pronounced [3 H]ACh release from cholinergic neurons. The estimated quantity of [3 H]ACh release per pulse of electrical stimulation was reduced by an increase in stimulus frequency, showing an inverse correlation between release probability of ACh and neuronal excitation. ACh release was also negatively regulated by pre-synaptic muscarinic ACh receptors (mAChRs). The autoinhibition induced by released ACh was predominantly suppressed by the M2 -selective antagonist AF-DX 116, partially inhibited by M3 -selective darifenacin, and minimally by M4 -selective PD 102807. Other subtype-selective antagonists had no effect at subtype-selective concentrations. ACh esterase (AChE) inhibitors (diisopropylfluorophosphate, donepezil and galantamine) at concentrations that mostly inhibit esterase activity reduced [3 H]ACh release, and the reduction was abolished by treatment with atropine. This implies that pre-synaptic autoreceptors are activated more after blockade of ACh hydrolysis, leading to autoinhibition of ACh release and consequent reduction in synaptic ACh concentrations. [3 H]efflux was also enhanced by ACh uptake inhibitors (100 µM hemicholinium-3 and physostigmine), regardless of ACh hydrolysis. This study shows that synaptic ACh concentrations in striatal cholinergic neurons are regulated in a complex manner by many factors such as release probability, pre-synaptic M2 /M3 /M4 mAChRs, AChE and post-synaptic ACh uptake, and provides important information about cholinergic neurotransmission for future exploration of therapeutic strategies for Alzheimer's and other central nervous system diseases. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/openscience-badges/.

Regulation of synaptic acetylcholine concentrations by acetylcholine transport in rat striatal cholinergic transmission.

In addition to hydrolysis by acetylcholine esterase (AChE), acetylcholine (ACh) is also directly taken up into brain tissues. In this study, we examined whether the uptake of ACh is involved in the regulation of synaptic ACh concentrations. Superfusion experiments with rat striatal segments pre-incubated with [3 H]choline were performed using an ultra-mini superfusion vessel, which was developed to minimize superfusate retention within the vessel. Hemicholinium-3 (HC-3) at concentrations less than 1 µM, selectively inhibited the uptake of [3 H]choline by the high affinity-choline transporter 1 and had no effect on basal and electrically evoked [3 H]efflux in superfusion experiments. In contrast, HC-3 at higher concentrations, as well as tetraethylammonium (>10 µM), which inhibited the uptake of both [3 H]choline and [3 H]ACh, increased basal [3 H]overflow and potentiated electrically evoked [3 H]efflux. These effects of HC-3 and tetraethylammonium were also observed under conditions where tissue AChE was irreversibly inactivated by diisopropylfluorophosphate. Specifically, the potentiation of evoked [3 H]efflux was significantly higher in AChE-inactivated preparations and was attenuated by atropine. On the other hand, striatal segments pre-incubated with [3 H]ACh failed to increase [3 H]overflow in response to electrical stimulation. These results show that synaptic ACh concentrations are significantly regulated by the postsynaptic uptake of ACh, as well as by AChE hydrolysis and modulation of ACh release mediated through presynaptic muscarinic ACh receptors. In addition, these data suggest that the recycling of ACh-derived choline may be minor in cholinergic terminals. This study reveals a new mechanism of cholinergic transmission in the central nervous system.

Toona sinensis leaf extract has antinociceptive effect comparable with non-steroidal anti-inflammatory agents in mouse writhing test.

BACKGROUND: The antinociceptive effect of an aqueous extract from the leaves of Toona sinensis (TS, [A. Juss., M. Roem.]) was studied using the writhing test in mice. METHODS: Different extraction fractions from TS leaf extracts (TSL1 to TSL5) were administered orally 1 h before intraperitoneal injection of acetic acid. RESULTS: After treatment with TSL1, TSL2, TSL3, TSL4, and TSL5 at a dose of 1 g/kg, the respective writhing responses were 39.9% (P < 0.001), 19.9% (P < 0.05), 11.7% (P = 0.052), 8.1% (P = 0.188), and 11.4% (P = 0.057) lower than the control group. Mice treated with TSL1 at 1 g/kg (39.9%, P < 0.001), 0.3 g/kg (38.0%, P < 0.001), 0.1 g/kg (46.9%, P < 0.001), and 0.03 g/kg (31.1%, P < 0.001) had significantly lower writhing responses compared with control mice. A time-course experiment was performed, which involved oral administration of TSL1 (0.1 g/kg) at 0, 0.5, 1, 2, and 6 h before acetic acid intraperitoneal injection. The most effective dose of TSL1 was 0.1 g/kg orally, with the effect beginning 30 min before treatment and persisting until 6 h. CONCLUSIONS: This study showed that TS has anti-visceral pain properties comparable with those of rofecoxib (a cyclooxygenase-2 inhibitor) and diclofenac, which suggests promise for the treatment of intractable visceral pain in humans.

Plasma levels of transforming growth factor-beta 1 before and after removal of low- and high-grade astrocytomas.

Transforming growth factor-beta 1 (TGF-ß1) has been reported to be a possible marker for a number of tumors, including brain tumors. The aim of this study was to measure the plasma levels of TGF-ß1 in patients with low- and high-grade astrocytomas before and after surgery. This prospective study included 14 patients with low-grade astrocytomas and 25 with high-grade astrocytomas who underwent tumor removal and 13 controls (patients who underwent cranioplasty for skull bone defects). Plasma levels of TGF-ß1 were measured in all subjects using enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic (ROC) curve analysis showed that when the level of TGF-ß1 before tumor removal was ≥ 2.52 ng/ml, astrocytoma was predicted with a sensitivity of 94.9% and specificity of 100%. The mean plasma level of TGF-ß1 in both the low-grade and high-grade astrocytoma groups significantly decreased after tumor removal (p<0.05); there was no significant change in TGF-ß1 plasma level of the controls following surgery. Patients with high-grade astrocytomas had a significantly higher mortality rate than patients with low-grade astrocytomas (p=0.019) and significantly shorter survival (p=0.008). A positive correlation between TGF-ß1 level after tumor removal and tumor volume was only found in the high-grade astrocytoma group (γ=0.597, p=0.002). The findings show that plasma TGF-ß1 level was increased in patients with low-grade and high-grade astrocytoma, and that the levels significantly decreased after tumor removal in both groups. The results provide additional evidence that TGF-ß1 might be useful as a tumor marker for astrocytomas.

Assisted peripheral nerve recovery by KMUP-1, an activator of large-conductance Ca(2+)-activated potassium channel, in a rat model of sciatic nerve crush injury.

BACKGROUND: Axonal regeneration in peripheral nerves after injury is a complicated process. Numerous cytokines, growth factors, channels, kinases, and receptors are involved, and matrix metalloproteinase-9 (MMP-9) has been implicated in the pathogenesis subsequent to nerve injury. In this study, the effect of KMUP-1, an activator of large-conductance Ca(2+)-activated potassium channel, on functional recovery, myelinated axon growth, and immunoreactivity of MMP-9 was evaluated in rats subjected to sciatic nerve crush injury. METHOD: A total of 144 male Sprague-Dawley rats were divided into the following six groups (n = 24/group): group 1, sham-operated; group 2, sciatic nerve injury without treatment; group 3, injured and vehicle-treated; group 4, injured and treated with 1 mM KMUP-1 by topical application; group 5, injured and treated with 10 mM KMUP-1; group 6, injured and treated with 50 mM KMUP-1. Functional recovery was evaluated using walking track analysis at 1, 2, 3, and 4 weeks (n = 6/group at each time point) after injury. In addition, the number of myelinated axons and MMP-9 in the nerve was also examined. FINDINGS: Animals subjected to sciatic nerve crush injury had decreased motor function, a reduced number of myelinated axons, and increased MMP-9 in the nerve. Treatment with KMUP-1 concentration-dependently improved functional recovery, increased the number of myelinated axons, and decreased MMP-9. CONCLUSIONS: These results suggest that KMUP-1 may be a novel agent for assisting peripheral nerve recovery after injury. The beneficial effect is probably due to known ability of the compound in activating the nitric oxide/cGMP/protein kinase G pathway.

Functional outcome analysis: instrumented posterior lumbar interbody fusion for degenerative lumbar scoliosis.

PURPOSE: Although instrumented posterior lumbar interbody fusion (PLIF) has been becoming a popular and effective method for treating degenerative lumbar scoliosis, the clinical outcome is rarely reported. We retrospectively evaluated the clinical and radiographic outcomes in patients with degenerative lumbar scoliosis after instrumented PLIF. MATERIALS AND METHODS: A total of 58 patient's clinical characteristics had been reviewed retrospectively including clinical presentations, preoperative medical comorbidities, intraoperative status, and postoperative status. Oswestry disability index (ODI), visual analog scale (VAS), and patient satisfaction were evaluated before surgery and last follow-up period. The relationship between the difference of radiographic parameter and functional outcome was evaluated. RESULTS: Functional outcomes including ODI scores and VAS were significantly improved at the last visit. The ODI was 28.1 ± 8.0 before surgery and 12.2 ± 8.8 at the last visit. VAS was 7.4 ± 2.0 before surgery and 2.4 ± 2.0 at the last visit. Patient satisfaction was 72% at the last visit. ODI was significantly related to postoperative radiographic parameters including Cobb's angle (p < 0.001), L4 inclination (p = 0.011), coronal balance (p = 0.007), lateral vertebral translation (p < 0.001), Nash-Moe grade (p = 0.033), Nash-Moe degree (p = 0.025), and sagittal balance (p = 0.041) Using multiple regression analysis, ODI was significantly related to female gender, number of levels fixed, coronal balance, lateral vertebral translation, and Nash-Moe degree. The was no significant correlation between postoperative radiographic parameters and pain (VAS). Only lateral vertebral translation demonstrated a significant correlation in multiple regression analysis. CONCLUSIONS: Based on the VAS and ODI instrument, our studies demonstrated that instrumented PLIF for adult degenerative lumbar scoliosis can achieve a high rate of patient satisfaction and improvement in radiographic and clinical outcomes at a minimum of 2 years of follow-up.

Assessment of novel muscarinic acetylcholine receptors in rat cerebral cortex by a tissue segment binding method.

Muscarinic acetylcholine receptors (mAChRs) of rat cerebral cortex were evaluated using a tissue segment radioligand binding assay. [(3)H]-Quinuclidinyl benzilate (QNB, a hydrophobic ligand) specifically bound to mAChRs in the cortex segments. The total mAChRs level was approximately 2,000 fmol/mg protein, which was estimated after incubation for 120 min at 37 degrees C or for 8 h at 4 degrees C. These mAChRs were a mixture of high- and low-affinity sites for N-methylscopolamine (NMS) in a 70:30 ratio. In contrast, only a single high-affinity site for NMS was detected following incubation for 30 min at 37 degrees C, whose abundance was about 70% of that of the total mAChRs. Atropine showed a single affinity for mAChRs under all conditions. These indicate that mAChRs are constitutively expressed not only on plasma membrane sites but also at intracellular sites in rat cerebral cortex and that the receptors at both sites have different affinities for NMS. Acetylcholine completely inhibited [(3)H]-QNB binding to both mAChRs without any change in the subcellular distribution, suggesting the possibility that acetylcholine can access, and bind to, both mAChRs in intact tissue. Two different affinity states for acetylcholine were detected only in plasma membrane mAChRs at 37 degrees C. The present study demonstrates a unique subcellular distribution, and distinct pharmacological profiles, of mAChRs in rat cerebral cortex.

The expression of thyroid hormone receptor isoforms in human astrocytomas.

BACKGROUND: Thyroid hormone plays a major role in normal mammalian brain maturation and affects the development of astrocytes. The expression of TR isoforms has been studied in different neoplasias. Increasing evidence has suggested that aberrant expression of TR isoforms could be associated with tumorigenesis. However, little was studied about the expression of TR isoforms in human astrocytomas. METHODS: In this study, RT-PCR was used to examine the expression of human TR isoforms in 34 human astrocytoma samples. RESULTS: We compared the TR expression between low grade (WHO grade II) and high grade (WHO grade III and IV). The frequency of TRalpha1 or TRalpha2 expression significantly decreased with the grade of malignancy (P=.005 and P=.043, respectively). However, the frequency of TRbeta1 expression significantly increased with the grades of malignancy astrocytomas (P=.017). CONCLUSIONS: Our study demonstrated for the first time that TR isoforms are indeed expressed in human astrocytomas. The expression of TR isoforms is correlated to the malignancy grading of astrocytomas. Our result provides insight into the potential use of hormonal therapy for brain tumors that overexpress or underexpress TRs.

The outcome of percutaneous computed tomography-guided chemical lumbar sympathectomy for patients with causalgia after lumbar discectomy.

BACKGROUND: Coldness, numbness, or causalgia usually affects the lower limbs in patients after back surgeries. The treatment of causalgia is still the source of continuing debate. We treated patients presenting with causalgia secondary to LD with CT-guided CLS and determined the therapeutic outcome at long-term follow-up. METHODS: From January 2002 to December 2002, a total of 15 patients (16 limbs) with causalgia after LD underwent the percutaneous CT-guided CLS. There were 7 male patients and 8 female patients, with an average age of 49.1 years. A total of 14 patients underwent unilateral procedures, and 1 patient underwent staged bilateral procedures. We followed up our patients for at least 24 months (24-36 months). RESULTS: There were 13 patients (14 limbs) diagnosed as Drucker stage I and 2 patients as stage II. There were 88% (14 limbs) that had an early satisfactory outcome after CLS and 75% (12 limbs) that had a late satisfactory outcome (more than 24 months after CLS). Stage I patients had more satisfying early and late outcome than stage II patients (P= .014 and P= .039, respectively). Female patients were more likely to have satisfactory late outcome than male patients (P= .034). There was no operative mortality. A patient had a complication of genitofemoral neuralgia, which had recovered in a month. CONCLUSIONS: We concluded that the percutaneous CT-guided CLS is an easy, safe, and reproducible technique, and it carries long-term benefit to patients with pain after LD presenting with causalgia, especially for patients with Drucker stage I and female patients.

Giant invasive schwannoma of cauda equina with minimal neurologic deficit: a case report and literature review.

A 53-year-old man presented with a history of slight weakness in the right lower limb. Giant invasive cauda equina schwannoma was diagnosed according to the criteria of Sridhar et al. Schwannomas are usually benign and common tumors arising from nerve sheath cells, particularly from sensory nerves. Giant invasive schwannomas, however, are rare, and most of patients with them present with severe neurologic deficits independent of daily activity, although in the case presented here, in spite of the large size of the tumor causing pedicle erosion, expansive destruction of the vertebral body and widening of the neural foramina, there were only minimal neurologic deficits. We have therefore decided to report this case, with a review of the relevant English literature emphasizing clinical presentations, plain film images and magnetic resonance image findings of giant invasive cauda equina schwannoma for early diagnosis and differential diagnosis.

Low-grade astrocytoma associated with abscess formation: case report and literature review.

A rare case of low-grade astrocytoma associated with abscess formation occurred in a 52-year-old man presenting with Broca's aphasia. He underwent craniotomy and tumor removal under the impression of brain tumor with necrotic cystic change. Abscess accumulation within the intra-axial tumor was found intraoperatively. Literature related to brain abscess with brain tumor is reviewed, with an emphasis on abscesses with astrocytoma. We discuss the common brain tumors that are associated with abscess, pathogens that coexist with brain tumor, and the pathogeneses of coexisting brain abscess and tumor. It is very important to know how to differentiate between and diagnose a brain abscess and tumor, or brain abscess with tumor, preoperatively from clinical presentation and through the use of computed tomography, conventional magnetic resonance imaging, diffusion-weighted imaging or magnetic resonance spectroscopy.

Attenuation of experimental subarachnoid hemorrhage--induced cerebral vasospasm by the adenosine A2A receptor agonist CGS 21680.

OBJECT: Impaired endothelium-dependent relaxation is present in vasospastic cerebral vessels after subarachnoid hemorrhage (SAH) and may result from deficient production of endothelial nitric oxide synthase (eNOS) or increased production and/or activity of inducible NOS (iNOS). Accumulating evidence demonstrates that adenosine A2A receptors increase the production of NO by human and porcine arterial endothelial cells, which in turn leads to vasodilation. This study was designed to examine the effects of an adenosine A2A receptor agonist, (2(4-[2-carboxyethyl]phenyl)ethylamino)-5'-N-ethylcarboxamidoadenosine (CGS 21680), in the prevention of SAH-induced vasospasm. METHODS: . Experimental SAH was induced in Sprague-Dawley rats by injecting 0.3 ml of autologous blood into the cisterna magna of each animal. Intraperitoneal injections of CGS 21680 or vehicle were administered 5 minutes and 24 hours after induction of SAH. The degree of vasospasm was determined by averaging measurements of cross-sectional areas of the basilar artery (BA) 48 hours after SAH. Expression of eNOS and iNOS in the BA was also evaluated. Prior to perfusion-fixation, there were no significant differences among animals in the control and treated groups in any physiological parameter that was recorded. The CGS 21680 treatment significantly attenuated SAH-induced vasospasm. Induction of iNOS mRNA and protein in the BA by the SAH was significantly diminished by administration of CGS 21680. The SAH-induced suppression of eNOS mRNA and protein was also relieved by the CGS 21680 treatment. CONCLUSIONS: This is the first evidence that adenosine A2A receptor agonism is effective in preventing SAH-induced vasospasm without significant complications. The beneficial effect of adenosine A2A receptor agonists may be, at least in part, related to the prevention of augmented expression of iNOS and the preservation of normal eNOS expression following SAH. Adenosine A2A receptor agonism holds promise in the treatment of cerebral vasospasm following SAH and merits further investigation.

Renal cell carcinoma presenting with skull metastasis: a case report and literature review.

The occurrence of metastasis to the head and neck region in renal cell carcinoma is extremely rare. An 80-year-old man presented with a soft nodule in the left parietal calvarium and was admitted to our hospital. Biopsy of the nodule showed nests of clear tumor cells, suggesting metastatic renal cell carcinoma. Computed tomography of the abdomen revealed a well-defined hypervascular tumor, measuring around 7 x 7 x 8 cm, exophytic from the lower pole of the right kidney. Since there were no other systemic metastases, right nephrectomy and complete resection of the skull lesion were performed. No adjunctive therapy was given postoperatively. After 22 months of follow-up, the patient was well and without evidence of disease.

Analysis of surgically treated intraspinal tumors in southern Taiwan.

The medical records of 117 patients with spinal tumors who underwent surgery with pathologic confirmation from January 1999 to April 2004 at Kaohsiung Medical University Hospital were reviewed. Data from this review were compared with those obtained from the same institution 10 years earlier (covering the period 1988-1995) and from other reported series. There were 69 male and 48 female patients aged from 13 to 87 years old (mean age, 51.9). The most common pathologic findings were metastasis in 45.3% (53/117), nerve sheath tumors in 28.2% (33/117), meningiomas in 12% (14/117) and neuroepithelial tumors in 6% (7/117). The peak ages at diagnosis were 41-50 years and 61-70 years. A slight male predominance was noted for all tumors, except meningiomas. Motor weakness, even paralysis, was the major clinical presentation (64-86%), followed by sensory deficits (50%) and pain (42%). The location of tumors was most often in the thoracic (50.4%; 59/117), lumbosacral (27.4%; 32/117) and cervical spine (22.2%; 26/117) segments. Among the metastatic tumors, the lung (22.6%) and breast (15.1%) were the most common primary sites of origin, followed by unknown origin, the liver (hepatocellular carcinoma), the gastrointestinal tract and the nasopharynx (nasopharyngeal cancer).

Odyssey between the constellations and neuromedicine.

The constellations have some connections with neuromedicine. As neurosurgeons, we can learn something from the night sky. Medical terms or descriptions are generously used from mythology or celestial lore. Neurosurgeons spend so much time on their professional careers that they may ignore something wonderful which is worthy of their attention. The puzzling issues between the constellations and neuromedicine can be exciting. Imagination allows neurosurgery to make great strides and progression. With that same imagination we can take an odyssey!

Erythropoietin ameliorates hyperglycemia in type 1-like diabetic rats.

BACKGROUND: Erythropoietin (EPO) is widely used in diabetic patients receiving hemodialysis. The role of EPO in glucose homeostasis remains unclear. Therefore, we investigated the effect of EPO on hyperglycemia in rats with type 1-like diabetes. METHODS: Rats with streptozotocin-induced type 1-like diabetes (STZ rats) were used to estimate the blood glucose-lowering effects of EPO, and changes in the expression levels of glucose transporter 4 (GLUT4) and the hepatic enzyme phosphoenolpyruvate carboxykinase (PEPCK) were identified by Western blot analysis. RESULTS: EPO attenuated the hyperglycemia in the STZ rats in a dose-dependent manner without altering the hematopoietic parameters, including the hematocrit and number of red blood cells. The involvement of the EPO receptor (EPOR) was identified using EPOR-specific antibodies. In addition, injection of EPO enhanced the glucose utilization, which was assessed using an intravenous glucose tolerance test in rats. However, blood insulin was not changed by EPO in this assay, showing the insulinotropic action of EPO. Moreover, EPO treatment increased the insulin sensitivity. Western blots indicated that the phosphorylation of AMP-activated protein kinase was enhanced by EPO to support the signaling caused by EPOR activation. Furthermore, the decrease in the GLUT4 level in skeletal muscle was reversed by EPO, and the increase in the PEPCK expression in liver was reduced by EPO, as shown in STZ rats. CONCLUSION: Taken together, the results show that EPO injection may reduce hyperglycemia in diabetic rats through activation of EPO receptors. Therefore, EPO is useful for managing diabetic disorders, particularly hyperglycemia-associated changes. In addition, EPO receptor will be a good target for the development of antihyperglycemic agent(s) in the future.

Amarogentin ameliorates diabetic disorders in animal models.

Amarogentin is a bitter-tasting secoiridoid glycoside isolated from an herb. Inhibition of aldose reductase by amarogentin has been documented as an antidiabetic action. However, the mechanisms of action of amarogentin in diabetic disorders remain unknown. The present study employed streptozotocin-induced type 1 diabetic (T1DM) rats to investigate the antihyperglycemic action of amarogentin. Changes in the protein expression of glucose transporter 4 (GLUT4) and phosphoenolpyruvate carboxykinase (PEPCK) in skeletal muscle and liver, respectively, were also detected by Western blotting. Additionally, a type 2 diabetes (T2DM) animal model induced using a fructose-rich diet was also applied to assess the effect of amarogentin on insulin resistance according to the homeostasis model assessment-insulin resistance (HOMA-IR). Amarogentin dose-dependently attenuated hyperglycemia in the T1DM rats lacking insulin. The action of amarogentin was further supported in rats administered the oral glucose tolerance test. Western blotting showed that amarogentin reversed the decreased GLUT4 level in skeletal muscle and reduced the elevated PEPCK expression in livers isolated from the T1DM rats. Moreover, amarogentin decreased the HOMA-IR and increased insulin sensitivity in the T2DM rats. These data show that amarogentin may ameliorate glucose homeostasis in diabetic rats, indicating its potential for future development as an antidiabetic drug.

Development of betulinic acid as an agonist of TGR5 receptor using a new in vitro assay.

BACKGROUND: G-protein-coupled bile acid receptor 1, also known as TGR5 is known to be involved in glucose homeostasis. In animal models, treatment with a TGR5 agonist induces incretin secretion to reduce hyperglycemia. Betulinic acid, a triterpenoid present in the leaves of white birch, has been introduced as a selective TGR5 agonist. However, direct activation of TGR5 by betulinic acid has not yet been reported. METHODS: Transfection of TGR5 into cultured Chinese hamster ovary (CHO-K1) cells was performed to establish the presence of TGR5. Additionally, TGR5-specific small interfering RNA was employed to silence TGR5 in cells (NCI-H716 cells) that secreted incretins. Uptake of glucose by CHO-K1 cells was evaluated using a fluorescent indicator. Amounts of cyclic adenosine monophosphate and glucagon-like peptide were quantified using enzyme-linked immunosorbent assay kits. RESULTS: Betulinic acid dose-dependently increases glucose uptake by CHO-K1 cells transfected with TGR5 only, which can be considered an alternative method instead of radioligand binding assay. Additionally, signals coupled to TGR5 activation are also increased by betulinic acid in cells transfected with TGR5. In NCI-H716 cells, which endogenously express TGR5, betulinic acid induces glucagon-like peptide secretion via increasing calcium levels. However, the actions of betulinic acid were markedly reduced in NCI-H716 cells that received TGR5-silencing treatment. Therefore, the present study demonstrates the activation of TGR5 by betulinic acid for the first time. CONCLUSION: Similar to the positive control lithocholic acid, which is the established agonist of TGR5, betulinic acid has been characterized as a useful agonist of TGR5 and can be used to activate TGR5 in the future.

Expression of Rac3 in human brain tumors.

Rac3 may play an important role in tumor growth but little is known about its expression and mutation in human tumor tissues. We examined the expression of Rac3 using RT-PCR and mutation of the Rac3 gene by DNA sequencing. Overexpression of the Rac3 gene occurred in 19% (5/26) of brain tumors; 3 of 9 (33%) meningiomas, 1 of 11 (9%) astrocytomas and 1 of 6 (17%) pituitary adenomas. Two of the 3 meningiomas with Rac3 overexpression were recurrent meningiomas. The only astrocytoma with Rac3 overexpression was a glioblastoma multiforme. Mutation of the Rac3 gene occurred in 63% (12/19) of brain tumours; 4 of 7 (57.1%) meningiomas, 4 of 5 (80%) pituitary adenomas and 4 of 7 (57.1%) astrocytomas. Except in one astrocytoma, the other four tumors with Rac3 overexpression (3 meningiomas and one pituitary adenoma) did not have Rac3 mutations. Our data is the first report of the frequency of Rac3 overexpression and mutation in human brain tumors. Overexpression may be associated with aggressive tumor behavior. The relationship between Rac3 expression and mutation requires further investigation.