Drugs online research references
Psychopharmacology (Berl). 1982;76(3):286-90.
Drug effects on discrimination performance at two levels of stimulus control.
Ksir C, Slifer B.
The effects of several doses of d-amphetamine, chlordiazepoxide (CDP), chlorpromazine (CPZ), LSD, pentobarbital, and scopolamine were examined in rats trained to respond to the brighter of two keys. On each of the 100 trials during a daily session, the rat pressed the key that was brighter (correct key) and received a food pellet, or pressed the incorrect key and terminated the trial without food, or pressed neither key for 10s, allowing the trial to terminate. Within a session, trials were mixed randomly such that on 50 trials the incorrect key was not lit (easy trials) and on 50 trials the incorrect key was dimly lit (difficult trials). Amphetamine (0.5-2.0 mg/kg) reduced percent correct responses, with a greater effect on difficult than on easy trials. CDP (4.0-16.0 mg/kg) and pentobarbital (2.0-16.0 mg/kg) reduced percent correct responses on the difficult trials at the highest doses tested. Scopolamine (0.12-1.0 mg/kg) reduced both percent correct (more so on the difficult trials) and percent of trials on which a response was made, in a dose-related fashion. CPZ (1.0-4.0 mg/kg) reduced trial responding at 2.0 and 4.0 mg/kg and reduced percent correct on the difficult trials at 4.0 mg/kg. LSD (0.08-0.32 mg/kg) did not significantly alter behavior in this study.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6808552&dopt=Abstract
Br J Pharmacol. 1985 Oct;86(2):505-8.
Muscarinic receptors discriminated by pirenzepine are involved in the regulation of neurotransmitter release in rat nucleus accumbens.
de Belleroche J, Gardiner IM.
The effect of pirenzepine, a selective muscarinic antagonist, was tested on the oxotremorine facilitation of the K+-evoked release of [14C]-dopamine from tissue slices of rat nucleus accumbens. The effect of pirenzepine was compared with that of scopolamine and other antagonists which show no heterogeneity in their action on muscarinic receptors in order to determine whether a selective action at a single receptor subtype, M1 or M2, could be distinguished. Pirenzepine and scopolamine both antagonized the oxotremorine-induced (EC50 = 3 X 10(-7) M) facilitation of [14C]-dopamine release with pA2 values of 7.5 and 8.9 respectively. This result indicated that the high affinity pirenzepine receptor (M1) was involved in this response. Low concentrations of 3-quinuclidinyl benzilate (3 X 10(-10) M), N-methylscopolamine (3 X 10(-9) M) and methyl atropine (10(-8) M) also abolished this facilitatory effect of oxotremorine.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2864975&dopt=Abstract
Scand J Gastroenterol Suppl. 1982;72:87-94.
Pirenzepine does not discriminate between pre- and postsynaptic muscarine receptors in the guinea-pig small intestine.
Halim S, Kilbinger H, Wessler I.
The effects of pirenzepine and scopolamine on presynaptic muscarine receptors (mediating inhibition of acetylcholine release) and postsynaptic receptors (mediating smooth muscle contraction) were compared in the myenteric plexus-longitudinal muscle preparation of the guinea pig. The preparation was preincubated with 3H-choline and subsequently superfused with Tyrode's solution. Field stimulation (1 Hz; 2 min) caused an outflow of 3H-acetylcholine that was depressed by the muscarinic agonist oxotremorine. Both pirenzepine and scopolamine produced shifts to the right of the concentration-response curve for the inhibitory effect of oxotremorine. Similarly, in contraction experiments, pirenzepine and scopolamine competitively antagonized the responses to oxotremorine. From the dose ratios pA2 values for pre- and postsynaptic effects were calculated. The presynaptic pA2 values for pirenzepine (6.90) and scopolamine (9.07) did not differ significantly from the respective postsynaptic pA2 values (6.66 and 9.40). Thus, pirenzepine like scopolamine does not distinguish between muscarine receptors that mediate contraction and those which mediate inhibition of acetyl-choline release.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6958001&dopt=Abstract
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