Polish journal of pharmacology and pharmacy最新文献

The effect of intra-accumbens injections of drugs changing the function of GABA-A and GABA-B receptor systems on stressor-induced motor depression, was studied in rats. Local injections of picrotoxin and baclofen, but not of midazolam and muscimol, attenuated the inhibitory effect of inescapable footshock on locomotor activity in the open field test, examined 24 h after a single exposure of rats to the stressful event. The results obtained with picrotoxin may be related to the general disinhibitory properties of the convulsant on brain neuronal activity, in a period of time important for consolidation of central processes evoked by inescapable shock. The lack of effects of muscimol and midazolam, further underlines the minor and/or indirect role of accumbens GABA-A receptor-related innervation in the neural processes generated by stressful event. On the other hand, the results obtained with baclofen confirm the reports indicating an inverse relationship between the number of GABA-B receptors in the frontal cortex and the development of helpless behavior in rats. It is also noteworthy that most antidepressant drugs which have been shown to prevent or reverse behavioral deficits after inescapable shock, upregulate GABA-B receptors in the frontal cortex. Hence, it appears that GABA-B receptor-related systems within the nucleus accumbens, may contribute to the footshock-induced behavioral depression, including locomotor inhibition. The reduction of stress effect by baclofen does not seem to reflect changes in fear and anxiety, since the drug was given after the stress session, and the anxiolytic midazolam appeared to be ineffective in this test.

Acylated derivatives of 4-methyl-1H-tetrahydro-1,5-benzodiazepin-2-one (1) and of 2-methyl-4-phenyl-1H-tetrahydro-1,5-benzodiazepino-2-carboxylic acid ethyl ester (10) were synthesized and preliminarily tested on their central activity. Acylation was carried out with alpha, beta-unsaturated acid chlorides, dicarboxylic acid monoester monochlorides, and dicarboxylic acid dichlorides. Compounds 2, 3, 11 and 12 had analgesic, compounds 4, 11 and 12--anticonvulsant, and compounds 3 and 11--antiaggressive properties.

Male Wistar rats were treated with morphine or pentazocine subcutaneously (sc) and then intrathecally (it) by methionine- or leucine-enkephalin, neurotensin, substance P or cholecystokinin octapeptide 26-33. Then antinociceptive effect was measured during 1 h using tail-immersion test. Leucine-enkephalin potentiated and methionine-enkephalin antagonized morphine or pentazocine analgesia. Neurotensin, substance P and cholecystokinin acted biphasically on morphine induced antinociception. After short elevation, the diminution of antinociceptive effect was seen. Neurotensin diminished but substance P and cholecystokinin elevated analgesic effect elicited by pentazocine. Experimental model employed by us may be useful for preliminary screening of pharmacological interactions between neuropeptides and opioid analgesics on the spinal level. Our data confirm the results of other authors that individual enkephalins have different pharmacological features.

The effect of combined treatment with doxepin and ethanol was tested in mice, rats and rabbits. Doxepin was given in a single dose (5 or 10 mg/kg) or chronically (10 mg/kg/d for 21 days). Doxepin did not affect ethanol toxicity and ethanol-induced impairment of rota-rod performance, but potentiated ethanol-induced hypothermia (only acutely) and prolonged ethanol-induced sleep in mice. Given acutely it potentiated the inhibitory effect of ethanol on locomotor activity in mice, while given chronically it counteracted the ethanol-induced sedation. Doxepin did not interfere with ethanol-induced EEG effects in rabbits, and prevented the development of tolerance to hypothermic, but not to hypnotic effects of ethanol in rats. In general, the interference of doxepin with ethanol was more pronounced after single doses of the drug than after chronic treatment.

The aim of the present study was to compare effects of intravenous infusion of vasopressin AVP and V1 receptors blockade on blood pressure and heart rate in normotensive (WKY) and spontaneously hypertensive (SHR) rats. A 20 min vasopressin infusion (1.2 ng/kg/min) elicited significantly greater increase in mean blood pressure (MP) in SHR than in WKY. Heart rate was significantly reduced in SHR while nonsignificantly in WKY. A 20 min dEt2 AVP (V1 antagonist) infusion (0.5 microgram/kg/min) elicited significant decrease in MP and increase in heart rate (HR) in SHR, but produced no effect in WKY. The data indicate that SHR are more susceptible to pressor and hypotensive effects of sustained elevation of AVP and AVP antagonist. The results support the hypothesis that AVP may contribute to pathogenesis of hypertension.

When all of the data concerning the role of D1 and D2 receptors in the control of unconditioned behaviors are taken together a fairly consistent picture begins to emerge. Considering first the normosensitive animals, it appears that D1 and D2 receptors are interdependent in their involvement in the control of locomotor activity. Stimulation of either receptor subtype leads to increases in activity although D2 agonists generally have a larger effect on activity than D1 agonists. Subeffective doses of D1 and D2 agonists (or D1 and D2 antagonists) have a synergistic action when co-administered. Injections of antagonists specific for either receptor subtype leads to a decrease in unstimulated locomotor activity or a diminution in the effects of agonists stimulating either receptor subtype. Besides locomotor activity, stimulation of D2 receptors produces yawning but a consistent effect on grooming has not been seen; D2 receptor stimulation also produces stereotyped behaviors. Again, there seems to be an interdependence between the two receptor subtypes; yawning or stereotypy produced by D2 receptor stimulation is blocked by either D2 or D1 antagonists. Stimulation of D1 receptors produces grooming and small perioral movements but not stereotyped behaviors like those typically seen following large doses of D2 agonists or DA agonists not specific a receptor subtype. Unlike D1 receptor-stimulated locomotor activity which is antagonized by D2 receptor blockers, grooming and perioral movements are not (but see Ref. 81). Thus, D1 receptor-mediated grooming and perioral movements seem to be exceptions to the otherwise general finding that co-stimulation of the two receptor subtypes needed for the expression of D1 or D2 agonist effects in normosensitive rats and mice. The apparent need to stimulate both D1 and D2 receptors to produce locomotor and some other unconditioned behaviors in normosensitive animals is lost in chronically denervated animals that are supersensitive to the effects of DA or DA agonists. However, there appear to be important species differences. Generally, in rodents undergoing unilateral or bilateral 6-OHDA-induced destruction of the nigrostriatal DA system, the locomotor effects of D1 agonists are not blocked by D2 antagonists and those of D2 agonists are not blocked by D1 antagonists. Similar results have been reported following chronic treatments with catecholamine depleting drugs. Thus, stimulation of either D1 or D2 receptors alone in DA supersensitive rodents appears to be sufficient to produce locomotor activity. In primates made DA supersensitive either with MPTP or as a result of Parkinson's disease, on the other hand, D2 but not D1 agonists are effective in reversing locomotor deficits.(ABSTRACT TRUNCATED AT 400 WORDS)

Some central effects of Ro 19-6327--a new MAO-B inhibitor--were studied in mice and rats. Given in low doses (1 or 3 mg/kg) Ro 19-6327 did not affect the locomotor activity of mice but its high dose (10 mg/kg) increased the activity. In rats Ro 19-6327 inhibited the locomotor activity but the effect was not dose dependent and not always significant. Ro 19-6327 did not change the locomotor activity in mice induced by L-DOPA (plus benserazide--an inhibitor of peripheral decarboxylase). The drug suppressed the reserpine-induced hypothermia and ptosis in mice and partly counteracted the apomorphine-induced hypothermia. It markedly enhanced (10 mg/kg) the amphetamine-induced stereotypy in rats. L-5-Hydroxytryptophan (L-5-HTP)-induced head twitch response was unchanged by Ro 19-6327. The drug given three times was inactive in forced swimming test. Repeated treatment with Ro 19-6327 (twice daily for 14 days) produced the enhancement of (+)-amphetamine- and nomifensine-induced hyperactivity in rats. Unlike a number of antidepressants, Ro 19-6327 did not potentiate the clonidine aggressiveness in mice, but--in contrast--inhibited it. The results suggest that Ro 19-6327 given repeatedly produces no changes in the responsiveness of the alpha-adrenergic system (in references to effects mediated by alpha 1-adrenoceptors). Adaptive changes in dopamine system are doubtful.

The MK-801-induced hyperactivity in rats was antagonized by haloperidol and, to a lesser degree, by SCH 23390, a dopamine D-1 antagonist, and sulpiride, a dopamine D-2 antagonist. Combined treatment with MK-801 + D-amphetamine, or MK-801 + apomorphine caused a stronger locomotor hyperactivity than each of those drugs given alone. The stereotypy evoked by D-amphetamine or apomorphine was not changed by MK-801. Atropine potentiated the effect of MK-801. Prazosin, idazoxan or ritanserin did not affect the MK-801-induced hyperactivity. It was reduced by pretreatment with alpha-methyl-p-tyrosine (alpha-MT) and completely abolished by pretreatment with reserpine, or with reserpine+alpha-MT. Also combined administration of MK-801 + clonidine increased the activity of rats pretreated with reserpine+alpha-MT. Our results indicate that the dopamine system is mainly involved in the locomotor hyperactivity induced by MK-801.

Plasma concentrations of carbamazepine (CBZ) were studied in 24 psychiatric patients who were given 400 mg of CBZ every 12 h. The assays were performed on the 1st, 3rd, 8th, 15th, 22th and 29th day of the therapy. The highest minimum 12h plasma CBZ concentrations occurred on the 3rd day of therapy, then decreased up to the 15th day and remained stable thereafter. The CBZ half-time values also diminished up to the 15th day of therapy and then stabilized. This may suggest that the enzymatic autoinduction of CBZ is completed within the first 1-2 weeks of therapy. CBZ plasma levels were slightly but insignificantly higher in patients taking CBZ alone than in patients in which CBZ was added to other psychotropic drugs. A significant correlation was found between the minimum CBZ plasma concentration after the first dose and that at steady state. A dosing schedule for CBZ administration has been proposed with administration of 75% of the maintenance dose during the first week and the full CBZ maintenance dose from the beginning of the second week of CBZ therapy.