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PubMed1996

[Effects of ding zhi pills on the scopolamine-induced impairment of passive avoidance in rats].

The Ding Zhi Pills described in "Thousand-Golden-Prescriptions" have better memory improving effect than those described in "Prescriptions People's Welfare Pharmacy". A combination of Poria, Radix Polygalae and Rhizoma Acori Graminei could enhance the pharmacologic effect of Radix Ginseng. Cinnabaris, described in "Prescriptions People's welfare Pharmacy", as one of the compositions in Ding Zhi Pills, does not improve the impairment of learning and memory, and therefore seems to have no meaning in the Ding Zhi Pills.

Animals↗
PubMed2006

Solid-liquid extraction and cation-exchange solid-phase extraction using a mixed-mode polymeric sorbent of Datura and related alkaloids.

Tropane alkaloids solid-liquid extraction methods were developed and comprised ambient pressure ones: extraction with hot solvent, extraction at room temperature, on ultrasonic bath as well as pressurised liquid extraction (PLE) techniques. The highest yields of l-hyoscyamine in methanol PLE method (3 x 5 min, 110 degrees C) and scopolamine extracted with 1% tartaric acid in methanol (15 min, 90 degrees C) were determined. A mixed-mode reversed-phase cation-exchange solid-phase extraction (SPE) procedure was optimised for simultaneous recoveries of L-hyoscyamine, scopolamine, scopolamine-N-oxide from plant extracts as well as quaternary alkaloid representative: scopolamine-N-methyl bromide. First three alkaloids were efficiently eluted (recoveries 80-100%) from an Oasis MCX cartridge with methanol-10% ammonia (3:1, v/v) solution, whereas for the quaternary salt tetrahydrofuran-methanol-25% ammonia (6:1:3, v/v) was used with recoveries 52-6%. HPTLC-densitometric assay on silica gel plates was elaborated at 205 nm without derivatization and included: single development (over a distance 9.5 cm) with acetone-methanol-water-25% ammonia (85:5:5:8, v/v) mobile phase for L-hyoscyamine and scopolamine separation, whereas for scopolamine-N-oxide and scopolamine-N-methyl bromide a second development (to a distance 5.5 cm) with acetonitrile-methanol-85% formic acid (120:5:5, v/v) was applied. Newly elaborated RP-HPLC-diode array detection method was performed on Waters XTerra RP-18 column with gradient of acetonitrile in 15 mM ammonia solution and alkaloids were baseline separated within 20 min. Both chromatographic methods were validated and their quantitative results were compared. Good correlation between HPLC and HPTLC quantitative results was measured (correlation coefficients of mean values were 0.92086 and 0.99995 for L-hyoscyamine and scopolamine, respectively). In the RP-HPLC method, which was from 1.5- up to 7-fold more sensitive than HPTLC, limits of detection (LOD) and limits of quantitation (LOQ, in bracket) were (in ng/microl) as follows: 0.25 (0.82) for L-hyoscyamine, 0.29 (0.97) for scopolamine, 0.13 (0.45) for scopolamine-N-oxide and 0.58 (1.91) for scopolamine-N-methyl bromide. By the use of the optimised chromatographic methods, 14 various samples from the leaves and fruits of Datura sp. were screened for L-hyoscyamine and scopolamine contents and the most promising samples were established.

Alkaloids↗
PubMed1995

Positive allosteric interactions on cardiac muscarinic receptors: effects of chemical modifications of disulphide and carboxyl groups.

Changes in the allosteric effects of alcuronium on rat cardiac muscarinic receptors were investigated after chemical modifications of S-S bonds or free carboxyl groups. In membranes pretreated with dithiothreitol, alcuronium lost its positive action on the binding of [3H]methyl-N-scopolamine while its inhibitory effect on radioligand dissociation was preserved. In membranes pretreated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), known to modify free carboxyl groups in proteins, the ability to bind [3H]methyl-N-scopolamine was preserved if the pretreatment had been performed in the presence of alcuronium, methyl-N-scopolamine or carbachol, while the positive cooperative effect of alcuronium on [3H]methyl-N-scopolamine binding was only preserved in membranes that had been exposed to EDC in the presence of alcuronium. Methyl-N-scopolamine, carbachol and alcuronium differed in their ability to protect (against EDC) the action of alcuronium on the rate of [3H]methyl-N-scopolamine dissociation. The results suggest that the disulphide bridge connecting the first two extracellular loops of muscarinic receptors is important for the positive allosteric action of alcuronium and that three carboxyl groups (presumably aspartate residues) are involved in receptor interactions with alcuronium and methyl-N-scopolamine. The first group is important for the effect of alcuronium on the affinity for methyl-N-scopolamine, the second is critical for the effect of alcuronium on the rate of methyl-N-scopolamine dissociation, and the third is critical for methyl-N-scopolamine binding. Presumably, the two charged nitrogens of alcuronium associate with the first and the second of the three groups involved.

Alcuronium↗
PubMed2004

Engineering tropane biosynthetic pathway in Hyoscyamus niger hairy root cultures.

Scopolamine is a pharmaceutically important tropane alkaloid extensively used as an anticholinergic agent. Here, we report the simultaneous introduction and overexpression of genes encoding the rate-limiting upstream enzyme putrescine N-methyltransferase (PMT) and the downstream enzyme hyoscyamine 6 beta-hydroxylase (H6H) of scopolamine biosynthesis in transgenic henbane (Hyoscyamus niger) hairy root cultures. Transgenic hairy root lines expressing both pmt and h6h produced significantly higher (P < 0.05) levels of scopolamine compared with the wild-type and transgenic lines harboring a single gene (pmt or h6h). The best line (T(3)) produced 411 mg/liter scopolamine, which was over nine times more than that in the wild type (43 mg/liter) and more than twice the amount in the highest scopolamine-producing h6h single-gene transgenic line H(11) (184 mg/liter). To our knowledge, this is the highest scopolamine content achieved through genetic engineering of a plant. We conclude that transgenic plants harboring both pmt and h6h possessed an increased flux in the tropane alkaloid biosynthetic pathway that enhanced scopolamine yield, which was more efficient than plants harboring only one of the two genes. It seems that the pulling force of the downstream enzyme (the faucet enzyme) H6H plays a more important role in stimulating scopolamine accumulation in H. niger whereas the functioning of the upstream enzyme PMT is increased proportionally. This study provides an effective approach for large-scale commercial production of scopolamine by using hairy root culture systems as bioreactors.

Alkaloids↗
PubMed1982

Anticholinergic drugs, blood-brain-barrier and tonic immobility in chickens.

A series of three experiments examined the effects of atropine, scopolamine, and their methyl analogs on tonic immobility in chickens. The first experiment demonstrated significant attenuation of immobility duration by atropine and scopolamine. Methyl atropine and methyl scopolamine attenuated immobility duration but did so significantly less than equivalent amounts of atropine and scopolamine. Experiments 2 and 3 examined effects of atropine, methyl atropine, scopolamine, and methyl scopolamine on immobility duration as a function of posthatch age. In these experiments atropine and scopolamine attenuated TI duration at each test age examined. The methyl analogs attenuated TI duration only at the youngest age (7-days posthatch) and failed to do so at 14-days posthatch or older. These age-dependent differences between the tertiary and quaternary compounds were attributed to blood-brain-barrier development. In Experiments 2 and 3 immobility duration increased with increased posthatch age. Scopolamine prevented the age-related increase but atropine did not. This difference is discussed in terms of fear arousal.

Aging↗
PubMed1996

Evidence for an involvement of muscarinic cholinergic systems in the induction but not expression of behavioral sensitization to cocaine.

The present study was designed to determine whether the muscarinic cholinergic antagonist scopolamine can prevent the expression and induction of sensitization to the locomotor-activating effects of cocaine. Rats received one daily injection of cocaine (20 mg/kg i.p.) for 5 days. Two days after withdrawal of pretreatment, rats were pretreated with scopolamine (3.0 mg/kg s.c) or its vehicle and challenged 15 min later with either saline or cocaine (20-30 mg/kg i.p.). In second set of experiments, scopolamine (3.0 mg/kg s.c) or its vehicle was given in combination with either saline or cocaine (20 mg/kg i.p.) for 5 days. Activity in response to saline and to cocaine (20 mg/kg i.p.) was assessed on day 7. The effects of acute administration of scopolamine (3.0 mg/kg s.c.) on cocaine-induced locomotor activity were also assessed. Acute administration of scopolamine increased both distance traveled and time spent in stereotypy. When scopolamine was administered 15 min prior to an acute injection of cocaine, a significant increase in the behavioral response to cocaine was seen. Daily injections of cocaine for 5 days produced sensitized behavioral responses to a subsequent cocaine challenge. Acute administration of scopolamine to animals preexposed and sensitized to cocaine did not disrupt the expression of sensitization to the locomotor and stereotypic effects of cocaine. In contrast, when scopolamine was given in combination with cocaine for 5 days, sensitization to the locomotor-activating effects of cocaine was prevented. These results suggest an important role of cholinergic muscarinic systems in mediating sensitization to the locomotor-activating effects of cocaine, which occurred after the repeated context-independent administration of this agent. In contrast, the enhanced stereotypic effects in response to the repeated administration of cocaine seem to be independent of alterations in muscarine cholinergic transmission.

Animals↗
PubMed1987

Muscarine receptors on the rat phrenic nerve, evidence for positive and negative muscarinic feedback mechanisms.

Neuronal transmitter stores of the rat phrenic nerve were labelled by incubation with [3H]choline. Release of [3H]acetylcholine was elicited by electrical nerve stimulation (100 or 1,500 pulses, 5 or 25 Hz) or by high potassium (27 mmol/l) and the effects of the muscarine receptor agonist oxotremorine and the antagonist scopolamine were investigated. Neither oxotremorine nor scopolamine affected the basal tritium efflux. A low concentration of oxotremorine (10 nmol/l) enhanced and a high concentration of oxotremorine (1 mumol/l) reduced the electrically evoked [3H]acetylcholine release. Likewise, the high potassium-evoked [3H]acetylcholine release was reduced by a high concentration of oxotremorine. Both effects of oxotremorine, increase and decrease, were abolished by a pretreatment (30 min before the first stimulation period) with 0.1 mumol/l scopolamine. Scopolamine (0.1 mumol/l) alone, enhanced [3H]acetylcholine release evoked by 100 pulses (5 Hz) or by high potassium. Scopolamine, however, reduced [3H]acetylcholine release evoked by 1,500 pulses (5 Hz or 25 Hz). The concentration-response curves obtained for scopolamine under these latter stimulation conditions were flat-running and biphasic which might indicate the involvement of two opposite effects (increase and decrease) of scopolamine under the present stimulation conditions. Both effects of scopolamine were reduced in the presence of 10 mumol/l neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed2000

Muscarinic receptor blockade has differential effects on the excitability of intracortical circuits in the human motor cortex.

The aim of the present study was to investigate whether muscarinic receptor blockade with scopolamine modifies the excitability of specific cortical networks of the human motor cortex as tested with transcranial magnetic stimulation. The effects of scopolamine on the excitability of human motor cortex were investigated in four healthy subjects using transcranial magnetic stimulation before and after an intravenous dose of scopolamine (0.006 mg/kg). We measured the threshold for motor responses, amplitude of motor responses, the duration of the cortical silent period, intracortical inhibition and facilitation, and short-latency inhibition produced by somatosensory input from the hand. In addition, we evaluated the amplitude of motor responses evoked by electrical anodal stimulation, since these responses originate from direct activation of corticospinal axons in the white matter and are not sensitive to changes in cortical excitability. Scopolamine decreased the threshold to magnetic stimuli and increased the amplitude of motor responses evoked by magnetic stimulation. In contrast, motor responses evoked by electrical stimulation were unaffected by administration of scopolamine. Scopolamine also led to a highly significant reduction in the amount of short-latency inhibition produced by somatosensory input from the hand. In contrast, short-latency intracortical inhibition and facilitation were not modified by scopolamine. The differential effect of scopolamine on motor responses evoked by magnetic and electrical stimulation of the motor cortex and the selective effect on somatosensory inhibition demonstrate that muscarinic blockade modifies the excitability of specific cortical networks in the human motor cortex.

Acetylcholine↗