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The effect of anticonvulsants on pentylenetetrazol (PTZ)-induced EEG power spectrum changes was examined. When the minimum dose of PTZ (15 mg/kg) was administered intravenously twice, with an interval of 80 min, a clear EEG power spectrum change was observed after the second PTZ administration, irrespective of whether or not the first PTZ administration evoked marked EEG changes. We defined the values F/N, S/N and S/F. The value F/N, obtained by dividing the power spectrum area after the first PTZ administration by the normal power spectrum area, was 1.06 +/- 0.05 (mean +/- S.E.). The value S/N, obtained by dividing the power spectrum area after the second PTZ administration by the normal power spectrum area, was 2.00 +/- 0.21. The value S/F, obtained by dividing S/N by F/N, was 1.86 +/- 0.16. The S/F value was almost constant regardless of whether or not the first PTZ administration could evoke marked EEG changes. The effect of anticonvulsants was examined by S/F value changes, and 100 mg/kg of PHT completely inhibited the double PTZ effect. Phenobarbital, ethosuximide and sodium valproate also inhibited the double PTZ effect. Using the S/F value of the EEG power spectrum with minimum dose double PTZ administration, quantitative evaluation is possible for anticonvulsant drugs.

Berberine has been shown to increase developed tension in cardiac muscle but its derivatives have been reported to inhibit the catalytic subunit of adenylate cyclase. In the present study, the cardiac actions of the most potent derivative, 13-propylberberine, were examined. It produced a transient increase followed by a sustained decrease in developed tension in paced left atrial muscle preparations isolated from guinea-pig heart. In the presence of 13-propylberberine, isoproterenol caused only a transient increase in developed tension; marked desensitization to the positive inotropic effect of isoproterenol occured within 20 min. After washout of isoproterenol and an additional 15-min incubation in the presence of 13-propylberberine, the muscle lost its sensitivity to isoproterenol. Moreover, the positive inotropic effect of ouabain or effects of decrease or increase in extracellular Ca 2+ concentration on the force of muscle contraction were markedly attenuated. Isoproterenol-induced elevation of tissue cyclic AMP concentration was inhibited by 13-propylberberine; however, 13-propylberberine did not alter the basal cyclic AMP concentration and its effects on inotropic actions of ouabain or extracellular Ca 2+ appear unrelated to tissue cyclic AMP concentration.

Physical dependence liability of chlorphenesin carbamate (CPC) was studied in parallel with phenobarbital-Na (PB). Beagle dogs were used and the overall duration of the experiment was 85 days, i.e. the first dosing period was 42 dyas (6 weeks) in which drugs were repeatedly administered orally once daily, followed by a withdrawal period (7 days), the second dosing period was continued from the 50th-78th day in which the form and schedule of drug administration was as in the first dosing period. The last 79th to 85th days were used for substitution experiments. In both dosing periods, PB but not CPC showed signs of tolerance formation. Severe withdrawal syndrome was observed in PB administered dogs whereas there were no changes of behavior observed in CPC-dogs by withdrawal and substitution procedures, respectively. CPC apparently does not have a physical dependence liability.

Δ1-Tetrahydrocannabinol (Δ1-THC, Ia) was oxidized with selenium dioxide to yield 7-hydroxy-(VI), 6α-hydroxy-(VIIa), 6β-hydroxy-(VIIIa) and 6-oxo-Δ1-THC (IX) together with cannabinol (CBN, III), 7-hydroxy-(X), 6-hydroxy-(XI) and 7-oxo-CBN (XII). Δ6-THC (IIa) was transformed merely to 7-hydroxy-(IVa) and 7-oxo-Δ6-THC (Va) in a similar manner. Individual products isolated are well defined mainly on the spectroscopic evidences. The oxidation of Ia favors the endocyclic allyl methylene rather than the exocyclic allyl methyl while the reverse is the case with IIa. Such a sharp contrast shown in their reactivities as mentioned above must be interpreted in terms of the steric interference at the reactive center.

Experiments were performed to investigate the effects of TJ-41 on spermatogenic disorders under current treatment with adriamycin (ADR). Male ICR mice were intraperitoneally injected with ADR at the dose of 0.15 mg/kg, twice a week for 5 weeks. Simultaneously, these mice were orally administered TJ-41 at the dose of 1, 2 or 4 g/kg for 12 weeks. The effects of TJ-41 were evaluated by histological analysis of germ cells in the testis at 7 weeks after the last injection of ADR. TJ-41 at a dose of 4 g/kg significantly inhibited the decrease of testis weight in mice treated with ADR. TJ-41 at doses of 1 and 4 g/kg significantly decreased the proportion of seminiferous tubules without germ cells as compared with the ADR-treated group. On the other hand, TJ-41 at doses of 1 and 4 g/kg significantly increased the proportion of normal seminiferous tubules and the Sertoli cell ratio of spermatocytes as compared with the ADR-treated group. These results indicate that TJ-41 may qualitatively and quantitatively protect against the decrease of germ cells in the testis of mice treated with ADR.

The s.c. administration of 20 mg/kg of morphine-HCl produced a decrease in the spontaneous locomotor activity (SLMA) of rats. The decrease in SLMA was significantly antagonized by p-chlorophenylalanine (p-CPA). When rats pretreated with p-CPA were given 5-hydroxytryptophan before morphine injection, the marked sedative response to morphine was restored, suggesting that the morphine-induced decrease in SLMA of rats may depend on the release of 5-hydroxytryptamine by morphine. By contrast, the s.c. administration of 5 mg/kg of morphine-HCl produced a significant increase in SLMA of rats. The magnitude of the increase was reduced by atropine, scopolamine or alpha-methyl-p-tyrosine. It appears that both adrenergic and cholinergic mechanisms participate in the increase in SLMA of rats induced by morphine. Both the increase in SLMA produced by 5 mg/kg of morphine and the decrease in SLMA induced by 20 mg/kg of morphine were completely antagonized by the s.c. administration of naloxone-HCl, 0.0625 and 0.25 mg/kg, respectively. Thus, it appears that the receptor with which morphine interacts to produce stimulation is chemically identical with or very similar to the receptor with which morphine combines to induce depression. The former receptors, however, are likely to be located on different neurons from the latter.

Adult male rats were administered morphine twice a day for 45 days and the effects of morphine on the copulation rate, the weight of various organs, and on the hypothalamic-pituitary-gonadal axis were examined. Morphine administered rats showed a loss of weight, hypertrophy of the adrenals, decreased weight of accessory sex organs, low sperm count, and decreased copulation rate. The contents of the luteinizing hormone releasing hormone in the hypothalamus and the luteinizing hormone in the pituitary remained unchanged. Serum luteinizing hormone and testosterone levels decreased, but serum follicle-stimulating hormone levels increased. These results suggest that morphine inhibits the hypothalamic-pituitary-gonadal axis and causes a diminution in the number of fertilizations of the partner females.

A rapid and sensitive method for determination of morphine in human urine using gas chromatography is described. The method involves charcoal absorption and solvent extraction of morphine followed by gas chromatographic analysis of the trimethylsilyl derivative. It is possible to detect morphine by this method more than 96 hrs after injection.

Either pethidine HCl (50 mg/kg s.c.) or methadone HCl (8 mg/kg s.c.) produced a prominent decrease in locomotor activity of rats. Pretreatment of rats with p-chlorophenylalanine (p-CPA, 320 mg/kg i.p.) 48 h before the narcotic injection significantly antagonized the activity-decreasing effects of narcotics. When rats pretreated with p-CPA were given 5-hydroxytryptophan (75 mg/kg s.c.) 30 min before narcotic administration, the activity-decreasing response to narcotics was restored. Thus, a decrease in locomotor activity induced in rats by either pethidine or methadone is probably mediated by serotonergic mechanisms.

Pharmacological actions of (6)-shogaol and capsaicin were studied. Both (6)-shogaol (0.5 mg/kg, i.v.) and capsaicin (0.1 mg/kg, i.v.) caused a triad such as a rapid fall in blood pressure, bradycardia and aponea in rats. Both drugs-induced marked pressor responses in blood pressure, which occurred after the rapid fall, were markedly reduced by a spinal destruction. In pithed rats, both drugs-induced peripheral pressor responses were markedly reduced with the combined treatment of [D-Arg1, D-Pro2, D-Trp7,9, Leu11]-substance P (0.5 mg/kg, i.v.), phentolamine (10 mg/kg, i.v.) and the section of sciatic nerves. In isolated guinea-pig trachea, (6)-shogaol (100 microM) and capsaicin (10 microM) induced contractile responses which were slightly inhibited by substance P antagonist (10 microM), but exhibited also a tachyphylaxis. Furthermore, although (6)-shogaol (3.6 microM) showed positive inotropic and chronotropic actions on isolated atria in rats, this effect of (6)-shogaol disappeared by repeated injections or pretreatment (100 mg/kg, s.c.) of (6)-shogaol. These results suggest that (6)-shogaol and capsaicin have similar actions, and that both drugs may cause a peripheral action by releasing an unknown active substance from nerve ends.

The radioimmunoassay for methamphetamine (I) in urine of man has been established by use of the 125I-labelled derivative of N-[3-(p-hydroxyphenylacetylamino) propyl]-methamphetamine (V) in sensitivity of 8.0 ng/100μl. The antigen binding capacity of the antiserum prepared form N-carboxymethylmethamphetamine-BSA (II) was determined by a new method of immunoassay using fluorescence labelled N-(3-dansylaminopropyl) methamphetamine (IV) ("fluoroimmunoassay"). The specificity of the antibody was examined by its cross reaction with several methamphetamine analogues.

General pharmacological studies were performed on (6)-gingerol and (6)-shogaol which are the pungent constituents of ginger (Zingiber officinale Roscoe). Intravenous (i.v.) administration of (6)-gingerol (at 1.75-3.5 mg/kg) or (6)-shogaol (at 1.75-3.5 mg/kg) and oral administration of them (at 70-140 mg/kg) produced an inhibition of spontaneous motor activity, an antipyretic and analgesic effects, prolonged hexobarbital-induced sleeping time, and these effects of (6)-shogaol were mostly more intensive than that of (6)-gingerol. (6)-Shogaol showed an intense antitussive effect in comparison with dihydrocodeine phosphate. In the electro-encephalogram of cortex, the low amplitude fast wave pattern was observed for 5 min after i.v. administration of (6)-shogaol, and then changed to the drowsy pattern, which was restored after 60 min. In the gastro-intestinal system, (6)-shogaol intensively inhibited the traverse of charcoal meal through the intestine in contrast with (6)-gingerol after i.v. administration of 3.5 mg/kg, but (6)-shogaol facilitated such an intestinal function after oral administration of 35 mg/kg. Both (6)-shogaol and (6)-gingerol suppressed gastric contraction in situ, and the suppression by the former was more intensive than that by the latter. In the cardiovascular system, both (6)-shogaol and (6)-gingerol produced depressor response at lower doses on the blood pressure. At high doses, both drugs produced three phase pattern.

The protective effects of TJ-8007 (Tsumura-Zokumeito, Traditional chinese medicine) against cerebral anoxia were investigated with various experimental models in mice and rats. 1) In histotoxic anoxia, TJ-8007 (0.3-3.0 g/kg, p.o.) dose-dependently demonstrated a protective effect on coma induced by a sublethal dose of KCN (1.8 mg/kg, i.v.) in mice. Ifenprodil (30 mg/kg, p.o.) tended to reduce the coma time, but papaverine (100 mg/kg, p.o.) showed a negative effect. 2) TJ-8007 (0.3-3.0 g/kg, p.o.) dose-dependently tended to prolong the survival time of mice subjected to a lethal dose of KCN (3.0 mg/kg, i.v.), TJ-8007 also improved the survival rate at the dose of 3.0 g/kg. Ifenprodil (30 mg/kg, p.o.) or papaverine (100 mg/kg, p.o.) exerted a similar effect on the survival time, but did not affect the mortality. 3) In the normobaric hypoxia with a gas mixture of 96% N2 and 4% O2, TJ-8007 (0.3-3.0 g/kg, p.o.) did not affect the survival time of mice. On the other hand, papaverine (100 mg/kg, p.o.) prolonged the survival time, and phenytoin (100 mg/kg, p.o.) showed a marked protective effect, but ifenprodil (30 mg/kg, p.o.) produced an adverse effect. 4) In the asphyxic anoxia induced by stopping artificial respiration of immovable rats, TJ-8007 (1.0, 3.0 g/kg, p.o.) showed a protective effect on the fall of systemic blood pressure and on the decline of heart rate; furthermore, it dose-dependently prolonged the disappearance time of cortical activity. Also, phenytoin (100 mg/kg, p.o.) tended to protect against the fall of blood pressure and prolonged the cortical resistance time.(ABSTRACT TRUNCATED AT 250 WORDS)

When (6)-shogaol (0.5 mg/kg, i.v.) was administered to rats, blood pressure showed a tri-phasic response which was comprised of a rapid fall, followed by a rise and a delayed fall. The rapid fall, which followed immediately after injection of (6)-shogaol, disappeared with the use of atropine and vagotomy. The marked rise, which occurred after the rapid fall, was not affected by alpha-adrenoceptor blockades, Ca antagonists and ganglion blockade. However, a combination of alpha-adrenoceptor blockade and Ca antagonist inhibited this pressor response. In hindquarters perfused with a nutrient solution, (6)-shogaol (10(-5) g)-induced peripheral pressor response was also not affected by alpha-adrenoceptor blockades and Ca antagonists, but was inhibited by the combination of an alpha-adrenoceptor blockade and a Ca antagonist. Furthermore, this peripheral pressor response was eliminated by the removal of Ca ion from the perfusate. (6)-Shogaol did not exhibit a pressor response in an artery and a vein of the tail or an artery of the femur perfused with a nutrient solution. (6)-Shogaol-induced peripheral pressor response in hindquarters was markedly potentiated during the perfusion of norepinephrine (5 X 10(-6) g/ml), but this potentiation was prevented by pretreatment with reserpine (5 mg/kg, i.p.). Moreover, repeated injections of (6)-shogaol caused a tachyphylaxis in mesenteric and tail vascular beds and a slight tachyphylaxis in hindquarters.

Summary: The El mouse is an inbred strain developed from ddY mice and is very susceptible to seizure. In El mice, convulsions could be induced by 18 mg/kg of pentylenetetrazol, which is an inert dose in ddY mice. The features of the convulsions were the same as those induced by the tossing-up procedure, a common method to evoke convulsions in El mice. Phenytoin, phenobarbital, valproate sodium, and ethosuximide clearly inhibited pentylenetetrazol-induced convulsions in El mice. These findings suggest that induction of convulsions by pentylenetetrazol in the El mouse is a simple method as compared with induction of convulsions by the tossing-up procedure, and convulsions evoked by this method are a precise experimental model for the study of hereditary epilepsy and for the evaluation of anticonvulsant drugs. RESUMEN El raton El es una cepa natural desarrollada a partir del raton ddY y muy susceptible a crisis. En el raton El, peuden inducirse convulsiones mediante 18 mg/kg de pentilentetrazol, que es una dosis inerte en el raton ddY. Las caracteristicas de las convulsiones fueron las mismas que las inducidas por el procedimiento de lanzamiento hacia arriba del animal que es un metodo habitual de producir convulsiones en el raton El. Fenitoina, fenobarbital, valproato sodico y etoxusimida claramente inhiben las convulsiones inducidas por pentilentetrazol en el raton El. Estos hallazgos sugieren que la induccion de convulsiones por pentilentetrazol en el raton El es un metodo sencillo comparado con la induccion de convulsiones mediante el procedimiento de lanzamiento hacia arriba, y que las convulsiones evocadas por este metodo son un modelo experimental preciso para el estudio de la epilepsia hereditaria y para la evaluacion de las drogas anticonvulsi vantes. ZUSAMMENFASSUNG Die El-Mause sind ein Inzuchtstamm der sich von den ddY-Mausen ableitet und sehr empfanglich fur Anfalle ist. Bei EL-Mausen konnten Konvulsionen durch 18 mg/kg Pentylentetrazol, eine ungefahrliche Dosis fur ddY-Mause, erzeugt werden. Das Aussehen der Krampfe entsprach dem, das durch Hochwerfen, einer ublichen Methode bei EL-Mausen Krampfe hervorzurufen, ausgelost werden konnen. Phenytoin, Phenobarbital, Natrium-Valproat und Ethosuximid inhibierten die Pentylentetrazol-induzierten Krampfe bei EL-Mausen. Diese Befunde deuten darauf hin, das die Induktion von Krampfen durch Pentylentetrazol bei der EL-Maus eine einfache Methode ist, verglichen mit der Induktion von Krampfen durch das Hochwerfen der Tiere und das Konvulsionen, die durch diese Methode hervorgerufen werden, ein gutes experimentelles Modell fur die Untersuchung der hereditaren Epilepsie und fur die Prufung der antikonvulsiven Medikamente darstellen.

TJN-101 [+)-(6S, 7S, R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy- 6,7-dimethyl-10,11-methylenedioxy-6-dibenzo [a, c] cyclooctenol) is one of the lignan compounds isolated from Schisandra fruits. When TJN-101 was administered orally at the doses of 3-100 mg/kg/day for 4 days, bile secretion, hepatic excretion of dye or hepatic hemodynamics 24 hr after the last dose was investigated in comparison with the phenobarbital (100 mg/kg/day)-treated group. Bile flow was dose-dependently increased; in contrast, biliary concentration of bile acids was decreased in TJN-101 (30 and 100 mg/kg/day)-treated groups. Similar changes were also observed in the phenobarbital-treated group. These results suggested that the enhancement of bile secretion caused by TJN-101 or phenobarbital was due to an increase of a bile acid-independent fraction. In the bromosulfophthalein (BSP) clearance test for liver function, both TJN-101 (30 and 100 mg/kg/day) and phenobarbital accelerated the disappearance from the blood and biliary excretion of BSP. Hepatic hemodynamics was examined by the hydrogen clearance method and measurement of liver wet and dry weight. Liver blood flow tended to increase in the TJN-101 (10-100 mg/kg/day) or phenobarbital-treated group. On the other hand, TJN-101 (3-100 mg/kg/day) or phenobarbital hardly altered the water content of the liver. These results suggested that the liver enlargement caused by both compounds was not accompanied with hepatic edema and that the enhancement of bile secretion or hepatic excretion of BSP might be related to an increase of liver blood flow.

Effects of the Japanese Kampo medicine ‘Shosaiko-to-go-keishika-shyakuyaku-to’ (TJ-960), which is a mixture of 9 herbal drugs and is practically equivalent to ‘Saiko-keishi-to’ (SK), on the pentylenetetrazol (PTZ)-induced EEG power spectrum changes were examined. The EEG power spectrum change with 2 PTZ administrations at an 80 min interval was clearly inhibited by oral administration of 1.0 mg/kg of TJ-960. By separate single administrations of the main component herbal drugs, Bupleuri radix, Cinnamomi cortex, Paeoniae radix and Zingiberis rhizoma, only Paeoniae radix showed statistically significant inhibition of PTZ-induced EEG power spectrum changes at a proportional dose of 1.0 mg/kg of TJ-960. The other main component herbal drugs showed no statistically significant inhibitory effect although they had a tendency to inhibit. These findings suggest that the Japanese Kampo medicine, TJ-960 (SK), has an inhibitory effect on PTZ-induced power spectrum changes and one of the component herbal drugs, Paeoniae radix, is the important component drug.

Effects of oral administration of gomisin A, one of the components isolated from Schizandra fruits, on liver injuries induced by CCl4, d-galactosamine and dl-ethionine and on liver microsomal drug-metabolizing enzyme activities were investigated. Gomisin A suppressed the increase of serum transaminase activities and the appearances of histological changes such as degeneration and necrosis of hepatocyte, inflammatory cell infiltration and fatty deposition in each type of liver injury. The repeated administration of gomisin A (30 or 100 mg/kg, p.o., daily for 4 days) induced an apparent increase of liver weight in liver-injured and normal rats. Gomisin A decreased serum triglyceride and lipid contents of the liver in biochemical studies. Increases of microsomal cytochrome b5 and P-450, elevations of NADPH cytochrome C reductase, aminopyrine N-demethylase and 7-ethoxycoumarin O-deethylase activities and decrease of 3,4-benzo(a)pyrene hydroxylase activity per cytochrome P-450 were observed after the administration of gomisin A. In addition, gomisin A was found to enhance the incorporation of 14C-phenylalanine into liver protein and to shorten the hexobarbital-induced sleeping time. These changes caused by gomisin A were similar to those by phenobarbital. However, gomisin A is distinctly different from phenobarbital in the finding that phenobarbital lessened the survival ratio of CCl4-intoxicated mice, but gomisin A did not. Our observation suggest that gomisin A shows an antihepatotoxic action by oral application and also has hypolipidemic (mainly triglyceridemic) and liver protein synthesis-facilitating actions and that the enlargement of the liver seen with gomisin A is the adaptive hypertrophy which is due to the induction of drug-metabolizing enzymes.

The effect of humoral modulators on the morphine-induced increase in locomotor activity of mice was studied. The subcutaneous administration of 10 mg/kg of morphine-HC1 produced a marked increase in locomotor activity in mice. The morphine-induced hyperactivity was potentiated by scopolamine and attenuated by physostigmine. In contrast, both methscopolamine and neostigmine, which do not penetrate the blood-brain barrier, had no effect on the hyperactivity produced by morphine. Pretreatment of mice with α-methyltyrosine (20 mg/kg i.p., one hour), an inhibitor of tyrosine hydroxylase, significantly decreased the activity-increasing effects of morphine. On the other hand, pretreatment with p-chlorophenylalamine (3×320 mg/kg i.p., 24 hr), a serotonin depletor, caused no significant change in the hyperactivity. The study suggests that the activity-increasing effects of morphine are mediated by the release of catecholamines from adrenergic neurons in the brain. And the results are consistent with the hypothesis that morphine acts by retarding the release of acetylcholine at some central cholinergic synapses. It is also suggested from collected evidence that the activity-increasing effects of morphine in mice are mediated by mechanisms different from those which mediate the activity-increasing effects of morphine in rats.

(6)-Shogaol-induced pressor responses in blood pressure of rats were studied. Intraventricular injection of (6)-shogaol (0.1 to 0.5 microgram) caused a pressor response in a dose-dependent manner. (6)-Shogaol (0.5 mg/kg, i.v.)-induced pressor response was markedly reduced by a spinal destruction to the sacral cord level. However, norepinephrine (10 micrograms/kg, i.v.)-induced pressor response was not affected by the spinal destruction. In rats in which the spinal cord was destroyed to the thoracic cord level, (6)-shogaol-induced pressor response was reduced by hexamethonium (10 mg/kg, i.v.) and phentolamine (10 mg/kg, i.v.), etc. When the spinal cord was destroyed to the sacral cord level, the pressor response was not affected by these blockades. In the hindquarters of rats which were perfused with rats' blood, (6)-shogaol caused two pressor responses on the perfusion pressure. The first pressor response, which was accompanied by a rise in systemic blood pressure, was reduced by hexamethonium but was not entirely eliminated by phentolamine. However, the pressor response disappeared with spinal destruction to the sacral cord level. The second pressor response, which occurred about when the systemic blood pressure regained its original pressure, was not affected by hexamethonium, phentolamine or spinal destruction. Pressor response induced by the injection of (6)-shogaol (10 micrograms) into the perfusion circuit was not affected by phentolamine and spinal destruction. Furthermore, (6)-shogaol-induced peripheral pressor response disappeared with the combined treatment of [D-Arg1, D-Pro2, D-Trp7.9, Leu11]-substance P (0.5 mg/kg, i.v.), phentolamine and the section of the sciatic nerves.

Using Yanagita's activity-level counter, effects of morphine administration upon the spontaneous activities of rats under various conditions were studied. And the following facts were elucidated;1. It was shown numerically that the more the size of the dose was large and the more the duration of morphine repetition was long, the faster and the stronger their spontaneous activities became.2. Such changes of the spontaneous activities of rats due to the repeated administration of morphine can be regarded as one the signs of tolerance.3. The changes of the spontaneous activities of rats or some sorts of tolerance occur as fast as the appearance of physical dependence.4. The mechanisms by which rats become hyperactive by the repeated administration of morphine may be explained chiefly by the development of tolerance to the sedative action of morphine and by the absence of tolerance to the excitatory action of the drug. However, the extraordinary increases recognized by the long term repetition of morphine request us further studies.5. As far as slow morphinization of rats is adopted, the abstinent phenomenon of the morphinized rats is sedation.6. The disappearance of tolerance after the cessation of morphine administration occurs very late, far later than the disappearance of abstinent phenomenon.7. Frequent administrations of nalorphine to the morphinized rats can not shorten the duration of tolerance retention after the cessation of the medication.

Increases both in spontaneous locomotor activity and in body weight were observed after the administration of morphine-HCl (100 mg/kg, i. p.) to tolerant rats. These signs were inhibited by pretreatment of the morphine-tolerant rats with cholinergic antagonists; the inhibition by scopolamine was greater than that by methscopolamine or atropine. These results suggest that both central and peripheral cholinergic mechanisms participate in the increases both in spontaneous locomotor activity and in body weight of tolerant rats after morphine administration.