Randomized clinical trial: rikkunshito in the treatment of functional dyspepsia--a multicenter, double-blind, randomized, placebo-controlled study.

BACKGROUND: Rikkunshito, a standardized Japanese herbal medicine, is thought to accelerate gastric emptying and relieve dyspepsia, although no large-scale, randomized, placebo-controlled trials of rikkunshito have been conducted. This study aimed to determine the efficacy and safety of rikkunshito for treating functional dyspepsia (FD). METHODS: FD patients received 2.5 g rikkunshito or placebo three times a day for 8 weeks in this multicenter, randomized, placebo-controlled, parallel-group trial. The primary end point was the proportion of responders at 8 weeks after starting test drug, determined by global patient assessment (GPA). The improvement in four major dyspepsia symptoms severity scale was also evaluated. In addition, plasma ghrelin levels were investigated before and after treatment. KEY RESULTS: Two hundred forty-seven patients were randomly assigned. In the eighth week, the rikkunshito group had more GPA responders (33.6%) than the placebo (23.8%), although this did not reach statistical significance (p = 0.09). Epigastric pain was significantly improved (p = 0.04) and postprandial fullness tended to improve (p = 0.06) in the rikkunshito group at week 8. Rikkunshito was relatively more effective among Helicobacter pylori-infected participants (rikkunshito: 40.0% vs placebo: 20.5%, p = 0.07), and seemed less effective among H. pylori-uninfected participants (rikkunshito: 29.3% vs placebo: 25.6%, p = 0.72). Among H. pylori-positive individuals, acyl ghrelin levels were improved just in rikkunshito group. There were no severe adverse events in both groups. CONCLUSIONS & INFERENCES: Administration of rikkunshito for 8 weeks reduced dyspepsia, particularly symptoms of epigastric pain and postprandial fullness. (UMIN Clinical Trials Registry, Number UMIN000003954).

Screening of novel nuclear receptor agonists by a convenient reporter gene assay system using green fluorescent protein derivatives.

Nuclear receptors represent a very good family of protein targets for the prevention and treatment of diverse diseases. In this study, we screened natural compounds and their derivatives, and discovered ligands for the retinoic acid receptors (RARs) and the farnesoid X receptor (FXR). In the reporter assay systems of nuclear receptors presented here, two fluorescent proteins, enhanced yellow fluorescent protein (EYFP) and enhanced cyan fluorescent protein (ECFP), were used for detection of a ligand-based induction and as an internal control, respectively. By optimizing the conditions (e.g., of hormone response elements and promoter genes for reporter plasmids), we established a battery of assay systems for ligands of RARs, retinoid X receptor (RXR) and FXR. The screening using the reporter assay system can be carried out without the addition of co-factors or substrates. As a result of screening of more than 140 compounds, several compounds were detected which activate RARs and/or FXR. Caffeic acid phenylethyl ester (CAPE), known as a component of propolis from honeybee hives, and other derivatives of caffeic acid up-regulated the expression of reporter gene for RARs. Grifolin and ginkgolic acids, which are non-steroidal skeleton compounds purified from mushroom or ginkgo leaves, up-regulated the expression of the reporter gene for FXR.

Expression of a gene for Mn-peroxidase from Coriolus versicolor in transgenic tobacco generates potential tools for phytoremediation.

In efforts aimed at the detoxification of contaminated areas, plants have many advantages over bacteria and fungi. We are attempting to enhance the environmental decontamination functions of plants by transferring relevant genes from microorganisms. When the gene for Mn-peroxidase (MnP) from Coriolus versicolor was expressed in transgenic tobacco plants, one line (designated fMnP21) expressed MnP activity at levels 54-fold higher than in control lines. When undamaged roots of transgenic plants were applied to liquid medium supplemented with 250 microM pentachlorophenol (PCP), the decrease in the level of PCP in fMnP21 (86% reduction) was about 2-fold higher than that in control lines (38% reduction). Expression of the gene for MnP in the transgenic plants had no obvious negative effects on their vegetative and sexual growth. Our system should contribute to the development of novel methods for the removal of hazardous chemicals from contaminated environments using transgenic plants.

Ganglioside GD1a inhibits HGF-induced motility and scattering of cancer cells through suppression of tyrosine phosphorylation of c-Met.

We previously reported that ganglioside GD1a, which is highly expressed in poorly metastatic FBJ-S1 cells, inhibits the serum-induced motility of FBJ-LL cells and that the metastatic potential of FBJ-LL cells is completely suppressed by enforced GD1a expression (Hyuga et al., Int J Cancer 1999;83:685-91). We recently discovered that hepatocyte growth factor (HGF) induces FBJ-LL cell motility. In the present study, the HGF-induced motility of FBJ-S1 cells was found to be one-thirtieth that of FBJ-LL cells. This motility of GD1a-expressing transfectants, which were produced by transfection of FBJ-LL cells with GM2/GD2 synthase cDNA, decreased with increases in their GD1a expression and HGF induced almost no motility in GD1a-pretreated FBJ-LL cells, indicating that GD1a inhibits the HGF-induced motility of FBJ-LL cells. The expression of the HGF receptor c-Met on FBJ-S1 cells, FBJ-LL cells, transfectants and a mock-transfectant was almost the same. The level of tyrosine phosphorylation of c-Met after HGF stimulation in FBJ-S1 cells, GD1a-pretreated FBJ-LL cells and a GD1a-expressing transfectant was significantly lower than in FBJ-LL cells and a mock-transfectant. These findings suggested that GD1a inhibits the HGF-induced motility of FBJ-LL cells through suppression of tyrosine phosphorylation of c-Met. HepG2 cells, a human hepatoma cell line, were used to investigate whether GD1a interferes with other cancer cells expressing c-Met. HepG2 cells did not express GD1a. HGF induced cell scattering of HepG2 cells and the scattering was inhibited by pretreating the cells with GD1a. The c-Met in the cells was autophosphorylated by stimulation with HGF, but after treating the cells with GD1a, the HGF-induced autophosphorylation of c-Met was suppressed. These results suggest that GD1a acts as a negative regulator of c-Met in cancer cells.

Dai-kenchu-to enhances accelerated small intestinal movement.

The present study was conducted to clarify the effects of Dai-kenchu-to on accelerated small intestinal movement. We evaluated the effects of Dai-kenchu-to and its constituent herbs (dried ginger root, ginseng, zanthoxylum fruit, and malt sugar) on carbachol-accelerated mouse small intestinal transit, and contractions induced by low-frequency electrostimulation (ESC), KCl, or acetylcholine (ACh) using isolated guinea pig ileum. Dai-kenchu-to (10-300 mg/kg, p.o.) significantly improved carbachol-accelerated small intestinal transit in a dose-dependent manner. Using a concentration with the compounded rate for Dai-kenchu-to 300 mg/kg, carbachol-accelerated small intestinal transit was also significantly improved with a single dose of dried ginger root or ginseng. At a concentration of 3 x 10(-5) g/ml or less, Dai-kenchu-to, dried ginger root, and ginseng all inhibited ESC but not KCl- or ACh-induced contractions. However, at a higher concentration of Dai-kenchu-to (10(-4) g/ml) or zanthoxylum fruit (10(-5) g/ml or more) the ESC were enhanced. Both Dai-kenchu-to and dried ginger root at 10(-3) g/ml remarkably inhibited the KCl-induced contractions. These results indicate that Dai-kenchu-to improves accelerated small intestinal movement and that dried ginger root and ginseng may be involved in this effect. It is also thought that the mechanisms mainly involve the direct inhibition of smooth muscle but with a contribution from neural inhibition.

Mechanism of atropine-resistant contraction induced by Dai-kenchu-to in guinea pig ileum.

To clarify the contractile mechanism of Dai-kenchu-to, the effects of hydroxy beta-sanshool (an ingredient of Zanthoxylum fruit), Zanthoxylum fruit (a constituent herb of Dai-kenchu-to) and Dai-kenchu-to were studied in mucosa-free longitudinal muscle of guinea pig ileum. Hydroxy beta-sanshool at 10(-7)-10(-5) g/ml induced dose-related contractions accompanied by autonomous contraction and produced an initial contraction at a concentration of 10(-4) g/ml or more. The contraction induced by hydroxy beta-sanshool (10(-5) g/ml) was significantly inhibited by tetrodotoxin or the capsaicin-receptor antagonist capsazepine. Although atropine or the substance P antagonist spantide tended to inhibit the contraction, a combination of atropine and spantide almost abolished the contraction by hydroxy beta-sanshool. The P2-purinoceptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid did not affect hydroxy beta-sanshool-induced contraction in the presence or absence of spantide. The tonic contractions by Zanthoxylum fruit (2 x 10(-4) g/ml) and Dai-kenchu-to (10(-3) g/ml) were significantly inhibited or tended to be inhibited by atropine, spantide, tetrodotoxin or capsazepine and were remarkably suppressed by the combination of atropine and spantide. These results suggested that acetylcholine release from intrinsic cholinergic nerves and tachykinins from sensory neurons are involved in the contractions induced by hydroxy beta-sanshool and that tachykinins may be involved in the atropine-resistant contraction by Dai-kenchu-to.

Effects of Dai-kenchu-to, a herbal medicine, on uterine and intestinal motility.

The effects of both Dai-kenchu-to and PGF(2alpha) on intestinal and uterine motility were studied in anaesthetized rabbits with force transducers implanted in the jejunum, ileum and uterus. A single intraduodenal administration of Dai-kenchu-to (300 mg/kg) enhanced the intestinal motility but not the uterine motility. However, intravenous administration of PGF(2alpha) (20 microg/kg) enhanced both intestinal and uterine motility. The effects of Dai-kenchu-to on the spontaneous contraction and contractile response of the isolated rat uterine strips to oxytocin, PGF(2alpha) or ACh were also studied. Oral administration of Dai-kenchu-to at 300 mg/kg for one week had no effect on either the spontaneous contraction or the contractile response of the uterus. These results indicate that Dai-kenchu-to may exert stimulatory effects on intestinal motility, as PGF(2alpha), but has no effect on the uterine motility, suggesting a selective effect on the gastrointestinal tract. Hence, Dai-kenchu-to may be safer than PGF(2alpha) in the treatment of postoperative adhesive ileus in women. However, more studies are needed to determine whether Dai-kenchu-to could be administered to pregnant women.

Mechanisms for contractile effect of Dai-kenchu-to in isolated guinea pig ileum.

The mechanisms by which Dai-kenchu-to (TJ-100), a kampo medicine, enhances gastrointestinal motility was investigated using isolated guinea pig ileum. TJ-100 induced contractions accompanied by autonomous contraction at a concentration of more than 3 x 10(-4) g/ml in a dose-related manner. The TJ-100-induced ileal contraction was suppressed by atropine and tetrodotoxin, but not by hexamethonium. This effect was partially suppressed in the presence of high concentrations of ICS 205-930, a serotonin 4 (5-HT4) receptor antagonist. In addition, TJ-100 showed an acetylcholine (ACh)-releasing action in the smooth muscle tissues of ileum. These results suggest that contractile response induced by TJ-100 is partially mediated by ACh released from the cholinergic nerve endings and that 5-HT4 receptors would be involved in the effect of TJ-100.

Asymptomatic inflammatory bowel disease with special reference to ulcerative colitis in apparently healthy persons.

OBJECTIVE: We examined cases of asymptomatic inflammatory bowel diseases, particularly asymptomatic ulcerative colitis, which were found in apparently healthy Japanese persons who underwent general health screening. METHODS: Patients with positive immunological fecal occult blood test (IFOBT) among approximately 236,000 persons participating in the health screening program at the Aichi Prefectural Center for Health Care for the past 9 yr underwent total colonoscopy. In patients with ulcerative colitis, we investigated the sex and age distributions, extent of lesion, endoscopic activity, incidence rate, and clinical course. RESULTS: In all, 35 cases of inflammatory bowel disease were detected, and 274 cases of colorectal cancer (not discussed here) were detected in the same population. The 35 cases of inflammatory bowel disease consisted of 19 cases of ulcerative colitis (12 of asymptomatic and minimally symptomatic ulcerative colitis, and seven of symptomatic or with past history of ulcerative colitis); five of intestinal tuberculosis; two of Crohn's disease; two of amebic colitis; and seven of endoscopic colitis. The 12 patients with asymptomatic and minimally symptomatic ulcerative colitis consisted of 11 men and one woman aged 36-63 yr (mean 46.2 yr). We classified these cases into three grades of severity according to endoscopic findings: four cases were mild, eight moderate, and none severe. Of these 12 cases, three were found endoscopically because of positive IFOBT, although barium enema was normal. Anatomic types of colitis cases included three of total colitis, three left-sided colitis, two proctitis, and four right-sided or segmental colitis. In one case, the disease extended proximally during the course of observation. CONCLUSIONS: We found 35 cases of inflammatory bowel disease because of positive IFOBT performed as part of a general health screening. Of these, 19 cases were ulcerative colitis. These included many asymptomatic and minimally symptomatic cases, which could be very important in helping to elucidate the natural history of ulcerative colitis; thus, long-term follow up is necessary.

Ascorbic acid improves postischemic vasodilatation impaired by infusion of soybean oil into canine iliac artery.

This study was conducted to (a) assess postischemic vasodilatation by changes in the vascular cross-sectional area using simultaneous intravascular two-dimensional and Doppler ultrasound before and after the infusion of Intralipid (Pharmacia & Upjohn, Peapack, NJ, U.S.A.); (b) evaluate how antioxidant ascorbic acid modifies the effects of Intralipid on postischemic vasodilatation: and (c) clarify the changes in plasma nitrite and nitrate (NOx-) levels after the infusion of Intralipid with and without ascorbic acid. Twenty-eight mongrel dogs were used to measure for vascular cross-sectional area and average instantaneous peak velocity in the iliac arteries after the 5-min occlusion of the arteries. Postischemic vasodilatation was impaired after the infusion of Intralipid (20%, 2 ml/kg) and this impaired response was reversed by the co-administration of ascorbic acid (30 mg/kg). NG-monomethyl-L-arginine completely abolished postischemic vasodilatation. Plasma NOx levels were significantly reduced after the infusion of Intralipid compared with baseline (11.6+/-0.4 vs. 12.9+/-0.3 microM, p = 0.025) and after infusion of Intralipid with ascorbic acid compared with baseline (11.8+/-0.5 vs. 13.1+/-0.4 microM, p = 0.047). We concluded that ascorbic acid reverses the endothelial dysfunction induced by Intralipid without increasing plasma NOx- levels and that deactivation of nitric oxide by oxidative stress is a primary contributor to Intralipid-induced impaired vasodilation.

Effects of lisinopril and nitrendipine on urinary albumin excretion and renal function in patients with mild to moderate essential hypertension.

The present study was designed to evaluate the effects of an ACE inhibitor, lisinopril, and a calcium antagonist, nitrendipine, on urinary albumin excretion (UAE) and renal function in mild to moderate essential hypertensive patients with microalbuminuria. After the 4-week drug-free period, 17 patients were randomly divided into two groups. The first group (group 1: n=8) received lisinopril 10-20 mg daily for 8 weeks followed by nitrendipine 5-10 mg daily for another 8 weeks. The second group (group 2: n=9) received nitrendipine 5-10 mg daily for 8 weeks followed by lisinopril 10-20 mg daily for another 8 weeks. The mean blood pressure (MBP) significantly decreased in a similar manner in both groups. UAE significantly decreased after 8 weeks of treatment with lisinopril in group 1 and after 8 weeks of subsequent treatment with lisinopril in group 2. On the other hand, UAE was not altered by treatment with nitrendipine. The changes in UAE were significantly correlated with changes in MBP after 8 weeks of treatment with nitrendipine, but not after 8 weeks of treatment with lisinopril. No significant changes in creatinine clearance, urinary excretion of sodium or urinary N-acetyl-beta-D-glucosaminide were observed by any treatment in either group. These results suggest that lisinopril, not nitrendipine, reduces UAE in essential hypertensive patients with microalbuminuria independently of its effective antihypertensive properties.

Effects of vitamin B-6 on (n-3) polyunsaturated fatty acid metabolism.

To investigate interactions between vitamin B-6 and fatty acid metabolism, male Wistar rats were fed a vitamin B-6 (B-6)-deficient diet consisting of 70% vitamin-free casein and 10% perilla oil [approximately 63% alpha-linolenic acid, (n-3)] for 5 wk. The amounts of linoleic acid (n-6) and arachidonic acid (n-6) in the B-6-deficient group changed only slightly compared with those in a pair-fed control group. The amount of linoleic acid increased and arachidonic acid decreased in the plasma total lipid fraction, and the ratios of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the B-6-deficient group were significantly lower than for the controls. The ratios of alpha-linolenic acid and EPA were higher, and DHA lower, in the B-6-deficient group than in the pair-fed control group in the total lipid as well as phospholipid fractions in liver microsomes. The activity of delta6-desaturase was significantly lower in the B-6-deficient group than in the pair-fed control group (approximately 64%), and acyl-CoA oxidase activity, an initial enzyme of the peroxisomal beta-oxidation pathway, was reduced by approximately 80% in the B-6-deficient group. These data suggest that B-6 deficiencies impair the metabolism of (n-3) PUFA from alpha-linolenic acid to EPA and DHA with the most pronounced reduction in the production of DHA.

Effect of surface roughness and calcium phosphate coating on the implant/bone response.

The influence of surface roughness and calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated. Four types of titanium implants, i.e. as-machined, grit blasted, as-machined with Ca-P sputter coating, and grit blasted with Ca-P sputter coating, were prepared. The Ca-P sputter-coating, produced by using the RF magnetron sputter technique, was rapid heat-treated with infrared radiation at 600 degrees C. These implants were inserted into the left and right femoral condyles and the left and right tibial diaphyses of the rabbits. After implantation periods of 2 and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. Histological evaluation revealed no new bone formation around different implant materials after 2 weeks of implantation. After 12 weeks, bone healing was almost completed. For both tibial and femoral implants, Ca-P coated implants always showed a higher amount of bone contact than either of the non-coated implants. On the other hand, surface roughness improved only the response to implants inserted into the tibial diaphysis. On the basis of these findings, we concluded that 1) deposition of a sputtered Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase, and 2) besides implant surface conditions the bone response is also determined by local implant site conditions.

Metabolism of theanine, gamma-glutamylethylamide, in rats.

The metabolism of theanine, one of the major amino acid components in tea (Camellia sinensis), was studied in rats. High-performance liquid chromatography (HPLC) with fluorometric detection was used to evaluate the nature of theanine's metabolites in plasma, urine, and tissues. In the urine samples collected after administration of 100, 200, and 400 mg each of theanine, intact theanine, L-glutamic acid, and ethylamine, these compounds were detected in a dose-dependent manner. When 200 mg of theanine was orally administered to rats, the plasma concentrations of theanine and ethylamine reached their highest levels about 0.5 and 2 h after administration, respectively. It seems most likely that the enzymatic hydrolysis of theanine to glutamic acid and ethylamine was accomplished in the kidney. These results indicate that orally administered theanine is absorbed through the intestinal tract and hydrolyzed to glutamic acid and ethylamine in the rat kidney.

Gastroprotection by Liu-Jun-Zi-Tang (TJ-43): possible mediation of nitric oxide but not prostaglandins or sulfhydryls.

Liu-Jun-Zi-Tang (TJ-43), a herbal medicine exerting gastroprotective action, was examined for its mechanism of action in rats. TJ-43 significantly inhibited gastric mucosal damage caused by absolute ethanol at doses over 500 mg/kg in a dose-dependent way. Pretreatment with indomethacin or with N-ethylmaleimide did not affect the gastroprotective effect of TJ-43. However, pretreatment with NG-nitro-L-arginine partially but significantly reversed the protective effect of this drug. These findings suggest that the gastroprotective effect of TJ-43 occurs partly through nitric oxide but not through prostaglandins or sulfhydryls.

Liu-Jun-Zi-Tang, a kampo medicine, promotes adaptive relaxation in isolated guinea pig stomachs.

Some patients with dysmotility-like functional dyspepsia present impaired reservoir functions such as gastric adaptive relaxation. A traditional Chinese herbal medicine, Liu-Jun-Zi-Tang, has been identified as an effective drug against dyspeptic symptoms and is widely used for therapy in such patients. In this study, we examined the effects of this drug on the gastric adaptive relaxation in isolated guinea pig stomachs. The changes in intragastric volume and pressure were recorded in the presence of atropine and guanethidine. Gastric adaptive relaxation was induced by luminal distention. Liu-Jun-Zi-Tang (100 mg/ml) induced gastric adaptive relaxation at a lower intragastric pressure and increased the % volume of the gastric adaptive relaxation and the absolute intragastric volume. Metoclopramide (2 mg/ml), trimebutine (6 mg/ml) and cisapride (2 mg/ml) did not affect gastric adaptive relaxation. It was inhibited by means of the incubation of the stomach with NG-nitro-L-arginine (100 microM). Liu-Jun-Zi-Tang (100 mg/ml), but not gastroprokinetics overcame the effect of NG-nitro-L-arginine. These results suggested that Liu-Jun-Zi-Tang promoted gastric adaptive relaxation. This effect might, at least in part, contribute to the symptom relief in patients with functional dyspepsia.

Pharmacological studies of the effect of Dai-kenchu-to on spontaneous contraction of isolated rabbit jejunum.

We studied the effects of Dai-kenchu to on the spontaneous contraction in isolated rabbit jejunum. Dai-kenchu-to (10(-3) g/ml) increased jejunal contraction, such as phasic like contraction and contractile amplitude. Zanthoxyli Fructus (2x10(-4) g/ml) exhibited an action identical to that of Dai-kenchu-to. While Zingiberis Siccatum Rhizoma (5x10(-4) g/ml) continuously decreased the amplitude of contraction. Ginseng Radix (3x10(-4) g/ml) and Saccharum Granorum (8x10(-3) g/ml) had no effect on spontaneous contraction. Dai kenchu-to and Zanthoxyli Fructus reversed the decrease of contraction produced by atropine. However, phasic like contraction induced in the absence of atropine was antagonized by atropine. Dai-kenchu-to and Zingiberis Siccatum Rhizoma further decreased spontaneous contraction in the presence of tetrodotoxin. It was clarified that Dai-kenchu-to possesses gastroprokinetic effect, and Zanthoxyli Fructus mainly contributed to this effect. It was suggested that the cholinergic and non cholinergic nervous systems were involved in increasing intestinal motility. It was also suggested that Dai-kenchu-to acted on multiple points of the intestine, and actions at these points might intensify to improve ileus.

Effects of Dai-kenchu-to on intestinal obstruction following laparotomy.

To confirm the usefulness of Dai-kenchu-to for intestinal obstruction, investigation of the effects of Dai-kenchu-to on postoperative intestinal adhesion was conducted. Repeated administrations of Dai-kenchu-to (100 or 300 mg/kg) significantly inhibited the formation of intestinal obstruction. Motor disturbance and inflammation are thought to be involved in the etiology of intestinal adhesion. A single treatment of Dai-kenchu-to (300 mg/kg) significantly reduce intestinal transit time in postoperative ileus and chemically induced ileus. Dai-kenchu-to (10(-4) g/ml) significantly inhibited COX-2 activity. These results suggest that Dai-kenchu-to prevents postoperative intestinal adhesion by gastroprokinetic and anti inflammatic effects. Dai-kenchu-to thus demonstrates positive effect on postoperative ileus.

Effects of anti-Parkinsonian drugs on neurobehavioural changes induced by bilateral 6-hydroxydopamine lesions in rats.

1. Effects of anti-Parkinsonian drugs on neurobehavioural changes induced by bilateral lesions of dopaminergic neurons were investigated in rats. 2. Dopaminergic neurons in rats were lesioned bilaterally by injection of 6-hydroxydopamine (6-OHDA; 8 micrograms) into the medial forebrain bundle at the level of the posterolateral hypothalamus. As a result, a decrease in locomotor activity and marked catalepsy and prolongation of grasping time were observed. 3. Levodopa, talipexole, bromocriptine and theophylline dose-dependently antagonized the decrease in locomotor activity induced by bilateral 6-OHDA lesions. These drugs also showed antagonistic effects on the appearance of catalepsy and prolongation of grasping time induced by bilateral 6-OHDA lesions. In contrast, trihexyphenidyl showed no antagonizing effect on the neurobehavioural changes induced by 6-OHDA lesions at any concentration tested. 4. Combined treatment with levodopa and talipexole antagonized the neurobehavioural changes induced by bilateral 6-OHDA lesions, whereas no marked changes were observed when either drug was administered separately. The same findings were noted with the simultaneous use of either levodopa (2 mg/kg) and theophylline (2 mg/kg) or talipexole (0.005 mg/kg) and theophylline (2 mg/kg). 5. These results indicate that this model may be useful for estimating the effects of drugs in the treatment of Parkinson's disease.