Effect of naltrexone administration on short-term memory in chronically ethanol-treated outbred rats.

AIMS: The purpose of this study was to evaluate the effect of naltrexone treatment for 21 consecutive days on short-term memory in ethanol-preferring and non-preferring outbred rats. METHODS: Ethanol preferring, non-preferring and control Wistar rats were treated with naltrexone [0.1 mg/kg intraperitoneally (i.p.)] for 21 consecutive days. Short-term memory was assessed by using an olfactory social recognition test. RESULTS: A single administration of naltrexone (0.1 mg/kg i.p.) to non-ethanol-treated animals facilitated social memory, whereas the drug did not affect short-term memory in either group of chronically ethanol-treated rats. Multiple naltrexone treatment also lowered alcohol intake in ethanol-preferring rats. CONCLUSION: Naltrexone-ethanol interaction does not seem to produce any negative effect on the short-term memory in outbred rats.

Lack of ifenprodil anxiolytic activity after its multiple treatment in chronically ethanol-treated rats.

AIMS: The purpose of this study was to assess the anxiolytic activity of ifenprodil in Warsaw high-preferring (WHP) and low-preferring (WLP) rats after chronic ethanol treatment. METHODS: WHP and WLP animals, their paired-ethanol-naive groups and control Wistar rats were treated with ifenprodil (1.0 mg/kg, intraperitoneally) for 21 consecutive days. Anxiolytic activity was evaluated by using the two-compartment exploratory test. In addition, the locomotor activity paradigm was also assessed. RESULTS: Ifenprodil did not affect this paradigm in all investigated groups. The ethanol treatment led to lowering of anxiolytic scores in WHP rats. Multiple ifenprodil administration showed an anxiogenic-like activity in both WHP- and WLP-ethanol-treated groups. CONCLUSIONS: Our results suggest that, under some conditions, the role of ifenprodil in the treatment of alcoholism may be insufficient to support its use.

Ethanol facilitation of short-term memory in adult rats with a disturbed circadian cycle.

The aim of this study was to evaluate the effect of 3-month ethanol treatment on olfactory social memory test performance using two inter-exposure intervals [30 min: short-term recognition (STR); or 120 min: long-term recognition (LTR)] in adult rats with a disturbed circadian cycle (DCC). Ethanol treatment both in ethanol-preferring and -non-preferring groups improved the STR task compared to control rats. However, LTR procedure triggered the opposite tendency. Moreover, no differences between control rats with DCC and those with normal diurnal rhythm in STR and LTR paradigms were observed. Our results suggest that, under some conditions, alcohol facilitates short-term memory in adult rats.

Effects of acamprosate and scopolamine on the working memory of rats in a three-panel runway task.

The aim of this study was to evaluate the effect of treatment with single (1x) and multiple (10x) doses of the anti-craving compound acamprosate (AC, calcium acetyl homotaurinate) on working memory in rats, using in a three-panel runway test. We measured tasks after the animals were treated with AC (500 mg/kg/d, i.p.); scopolamine (SC, 0.5 mg/kg/d, i.p.), a cholinergic muscarinic receptor antagonist; or both drugs concomitantly (ACSC), either for 1 day (1x) or daily for 10 consecutive days (10x). Neither 1x not 10x AC alone had a significant effect on working memory task performance, whereas treatment with SC alone had a significantly negative effect on the ability of the rats to complete the tasks. Rats receiving ACSC performed better than those receiving SC alone, making fewer errors and displaying shorter latency, similar to the performance of the control group. These observations support the hypothesis of an indirect involvement of AC in the cholinergic system.

Analysis of the distribution of peripheral blood lymphocyte subsets associated with chronic ethanol treatment in rats with a disturbed circadian cycle.

The present study examined the composition of lymphoid subsets in the peripheral blood of alcohol-preferring (PRF) and non-preferring (NPF) rats, in an experimental model of alcoholism involving the disruption of the circadian cycle. The absolute and relative number of lymphocytes in specific subsets (CD3, CD4, CD8, NK, CD45RA) were measured using the flow cytometry method. When control animals with a disrupted circadian cycle (KN) were compared with a normal diurnal cycle group (KD), it was noticed that this disruption led to an increase in the absolute number of lymphocytes T (CD3(+), CD4(+) and CD8(+) cells) and lymphocytes B (CD45RA(+)). After the period of time when the alcohol preference was seen, there was a change in response - as measured by the numbers and the percentage of lymphoid subsets in NPF rats - involving a lowering of NK and CD45RA(+) cells. It seems that these animals exhibit higher sensitivity towards prolonged ethanol intoxication. However, the PRF animals - for whom the analysed values were close to those of the control group (KN) - tolerated the toxic effects of ethanol better and this may be related to their genetic predisposition.

The effects of midazolam and morphine on analgesic and sedative activity of ketamine in rats.

The aim of this study was to investigate possible interactions between the analgesic activity of ketamine (an N-methyl-D-aspartate antagonist), midazolam (a benzodiazepine derivative) and morphine using the tail-flick test in rats. Animals were treated s.c. with ketamine (1.0-10.0 mg/kg), midazolam (0.3 mg/kg), or morphine (0.6 mg/kg) alone. or in combination The strongest analgesic effect of ketamine was observed after 3.0 mg/kg. In higher doses no enhancement of ketamine activity were found. After morphine and ketamine (3.0 mg/kg) or morphine, midazolam and ketamine co-administration. higher antinociceptive effects compared to ketamine activity were found. Rats administered midazolam and ketamine (3.0 mg/kg) showed a decrease of the effect of ketamine analgesia, and the antinociceptive effect of the three-component mixture was lower than after co-injection of morphine and ketamine. The interaction of these two compounds with ketamine (5.0 mg/kg) occurred in a different manner, because midazolam led to a strong enhancement of ketamine analgesia. After morphine and ketamine (5.0 mg/kg) administration, very weak increase of ketamine analgesia was observed. The results of this study allow better understanding of the alteration of the analgesic effects of low doses of ketamine under the influence of morphine and midazolam.

Zolpidem involvement on memory and hypnotic effect of ethanol in chronically ethanol-treated rats.

Multiple (10x) treatment of zolpidem (1.0 or 2.0 mg/kg, orally, p.o.) led to different effects in chronically ethanol-treated and control rats. In control rats, after repeated zolpidem administration, a weaker, when compared to single administration, hypnotic effect of ethanol was observed, which may be the result of tolerance developed towards the inhibitory effect of zolpidem. However, in chronically ethanol-treated rats, the multiple zolpidem treatment led to prolongation of ethanol-induced sleep similar to the values observed in non-zolpidem-treated control animals. This suggests that zolpidem multiple administration may inhibit tolerance towards ethanol in chronically ethanol-treated rats. In the experiment with zolpidem, there were effects on performance in a memory test and the impairment of passive avoidance task after multiple drug treatment when compared to the effects after single administration in control rats. In contrast, in chronically ethanol-treated rats, amplification of latency (especially after 2.0 mg/kg) was observed. The possible relationship between ethanol-induced sedation and latency values would be consistent with a higher contribution of the inhibitory effect of zolpidem, than a direct influence on memory processes in chronically ethanol-treated rats.

The effect of chlorpromazine on pharmacokinetics and pharmacodynamics of phenobarbital in X-irradiated rats.

Male Wistar rats were irradiated with a single 600R dose of X-rays on the whole body. Chlorpromazine was given 30 min before phenobarbital. Phenobarbital sleeping time was prolonged by chlorpromazine both in irradiated and non-irradiated rats. On the 3rd day after irradiation the prolongation of the phenobarbital sleep by chlorpromazine was more marked than on the 6th day. No correlation between the pharmacodynamic action of phenobarbital and its cerebral level was noted.

Pharmacodynamics and pharmacokinetics of psycholeptic drugs in the course of radiation disease. Effect of premedication with metanabol on dynamics and kinetics of nitrazepam.

The effect of metanabol given to rats before irradiation (600 R) on exploring motility and cataleptic action of nitrazepam was investigated. The level of nitrazepam in the blood plasma and urine was determine. Most evident radioprotective effect of metanabol was found on 3rd day after irradiation. The drug inhibited the inhibited the increased response of the rats to the anticonvulsive action of nitrazepam and prevented the pharmacokinetic disturbances appearing in the course of radiation disease.

Influence of tricyclic antidepressant drugs on experimental arterial hypertension.

The tricyclic antidepressant drugs: imipramine, opipramol, amitryptiline and nortryptiline inhibit development of experimental arterial hypertension in rats.

Influence of the vaccine Polyvaccinum mite on the nasal mucosa.

The necessity of prolonged administration of the vaccine Polyvaccinum prompted this study on the effect of the preserving agent on the nasal mucosa. Buffered physiologic saline solution containing 0.1--0.4% phenol, and the vaccine containing 0.1--0.4% phenol or 0.01% merthiolate were applied for 12 weeks on the nasal mucosa of rabbits. The nasal mucosa, parenchymal organs and adrenals were studied macroscopically and histologically, and immunologic studies were made. On the basis of the results, preservation of Polyvaccinum mite with 0.4% phenol is suggested.