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A Bacchi

Publications and source records attributed to A Bacchi.

33 records · Page 2Linked to original sources
PubMed1993

Effects of buprenorphine on motility in chronically morphine treated rats.

The effects of buprenorphine (0.01-0.1 mg/kg) on the activity of nondependent and morphine dependent rats (a 20 mg/kg dose for 28 days) were determined. In naive animals buprenorphine exhibited both depressive and stimulatory actions upon the motility of rats, as repeatedly described for morphine. When buprenorphine was administered to rats chronically treated with morphine, the depressive effect disappeared (cross-tolerance to the inhibitory action); on the contrary the excitatory effect was enhanced (cross-sensitization). The results are discussed in terms of cross-sensitization to the excitatory effects in morphine dependent animals as predictor of morphine-like addictive properties in humans.

Animals↗
PubMed1992

Spontaneous release of interleukin-I and interleukin-6 by peripheral blood mononuclear cells after oophorectomy.

1. We studied the changes in interleukin-1 and interleukin-6 secretion by peripheral blood mononuclear cells from 12 premenopausal women after oophorectomy and seven premenopausal women who had undergone simple hysterectomy. 2. The results showed that 1 month after surgery interleukin-1 secretion increased by 414 +/- 171% (mean +/- SEM) and interleukin-6 secretion increased by 1354 +/- 481% in oophorectomized women, whereas only non-significant fluctuations in the secretion of both cytokines (-9% +/- 29% for interleukin-1 and -31% +/- 19% for interleukin-6) were seen in the women who had undergone simple hysterectomy. The difference between the two groups was significant (P = 0.035 for interleukin-1 and P = 0.003 for interleukin-6). In addition, oophorectomy, but not simple hysterectomy, was followed by significant increases in plasma ionized calcium concentration (P < 0.05), plasma alkaline phosphatase activity (P < 0.01) and plasma osteocalcin concentration (P < 0.02), and a reduction in plasma parathyroid hormone level (P < 0.01). 3. We conclude that ovary ablation may modify cytokine secretion by peripheral blood mononuclear cells. If this phenomenon occurs in the bone microenvironment, it could be important in the loss of bone observed after oophorectomy. However, the possibility of an independent alteration induced by the lack of gonadal hormones but unrelated to bone turnover cannot be excluded.

Adult↗
PubMed1991

Role of repeated exposure to morphine in determining its affective properties: place and taste conditioning studies in rats.

Male Sprague Dawley rats were injected daily with saline (morphine naive rats) or 20 mg/kg morphine (morphine experienced rats), starting at least 12 days before training. Subsequent place and taste conditioning indicated that 2.5 mg/kg morphine caused a significant increase in the amount of time spent on the least preferred side by morphine experienced but not by morphine naive rats; furthermore, saccharin consumption was markedly decreased and slightly increased by 10-20 mg/kg morphine in naive and experienced rats, respectively. It was concluded that morphine experience enhances the reinforcing efficacy of morphine and broadens the conditions under which the drug is reinforcing; thus it possibly increases morphine abuse potential.

Animals↗
PubMed1990

Morphine attenuation of a conditioned emotional response in post-dependent rats.

Rats placed in a test chamber where they had received repetitive shocks the previous day significantly reduced their motor activity; this was taken as indicator of a conditioned emotional response. Morphine attenuated this conditioned suppression of motility, possibly due to a reduction of the anxiety associated with the expectation of the noxious stimuli. Previous morphine dependence (20 mg/kg daily for 26 days) did not modify the effect of the opioid on the conditioned suppression of motility. This fact suggests that the action of morphine on pain anticipatory anxiety is similar in non-dependent and in post-dependent rats. Opioids are considered to produce pain relief in part by decreasing the anticipatory anxiety. The present results thus indicate that this important component of the analgesic action of morphine is unchanged in post-addicts.

Animals↗
PubMed1989

Cross-tolerance between morphine and clonidine: a study on motility in rats.

The effects of clonidine on motility were determined in non-dependent, morphine-dependent (a 20 mg/kg dose i.p. for 26 days) and post-dependent rats. In naive animals, clonidine (30-100 micrograms/kg) produced a dose-related suppression of motility. However, when the drug was administered in morphine-dependent rats, it induced slight hyperactivity at small doses and a decrease of activity only at the largest dose (100 micrograms/kg). Thus, tolerance to morphine conferred cross-tolerance to clonidine. On the contrary, the effects of clonidine on motility in post-dependent animals did not differ from those observed in control animals. The results are discussed in terms of similarities and differences between the depressant and excitatory effects of morphine and clonidine.

Animals↗
PubMed1989

Time-dependent generalization of morphine stimulus properties to meperidine: antagonism by naloxone.

The time course of the stimulus generalization to morphine by meperidine (20 mg/kg) was determined in rats trained to discriminate morphine (10 mg/kg) from saline in a standard two-lever procedure with food reinforcement. It was found that morphine lever selection following meperidine was a strictly time-dependent phenomenon. Naloxone (0.3 mg/kg) antagonized the stimulus properties of both morphine and meperidine; however, the antagonism was significantly more pronounced against morphine. The results suggest that there may be certain differences in the neuropharmacology of the stimulus properties of morphine and meperidine.

Animals↗
PubMed1987

Increased sensitivity to the stimulus properties of morphine in food deprived rats.

Recent research has shown that food deprivation increases opiate self-administration; in this line a first purpose of the present experiments was to determine whether the food deprivation effect could be replicated by the use of place conditioning, an alternative procedure for the study of drug reinforcement. It was found that the conditioned reinforcing properties of morphine (2.5 mg/kg IP) paired cues are greater in food deprived rats both after 1 and 3 conditioning sessions. A second objective of the work was to examine the possibility that food deprivation could also influence the discriminative stimulus properties of opiates. To this end rats trained to discriminate 10 mg/kg IP of morphine from saline were submitted to morphine generalization tests when food deprived or after 15 min supplemental feeding in the home cages. The ED50 value was significantly lower for food deprived (6.09 mg/kg) than for partially satiated (7.79 mg/kg) rats. It was concluded that food deprived rats are mores sensitive to both the reinforcing and the discriminative stimulus properties of morphine.

Animals↗
PubMed1986

Sensitivity to the narcotic cue in non-dependent, morphine-dependent and post-dependent rats.

Using a food-reinforced two-lever operant procedure, 12 rats were trained to discriminate 10 mg/kg (i.p.) of morphine from saline. Five animals were given daily non-contingent exposure to morphine (20 mg/kg on saline, or no-test days, and 10 mg/kg on drug days) from the beginning of the experiment; the others received injections of saline. In the morphine generalization tests, the dependent rats showed an increased sensitivity to the narcotic cue as compared with non-dependent animals (ratio of the ED50 values: 2.30). This increased sensitivity was still present 3 months after discontinuing the non-contingent treatment with morphine (ratio of the ED50 values: 1.98). The results of the present study, together with other results reported in the literature, suggest that the experimental procedure plays a role in determining whether tolerance, no tolerance or enhanced sensitivity to the discriminative stimulus properties of narcotics, is observed.

Animals↗
PubMed1985

Cross-sensitization to the excitatory effect of morphine in post-dependent rats.

Time-effects of morphine, methadone, meperidine and pentazocine upon locomotor activity were investigated in naive and in post-dependent rats. Dependence was induced by daily injection of 20 mg/kg (i.p.) of morphine for 30 days. Tests were run starting from 1 month after withdrawal from morphine. Morphine produced a greater increase in activity in post-dependent than in naive rats. Marked cross-sensitization to the excitatory effect occurred with methadone but not with pentazocine. The motility pattern of meperidine was similar in naive and in post-dependent animals. The findings presented here suggest that: different mechanisms underlie the excitatory actions of opiates; the narcotic character of a drug can be detected by challenging this drug in rats previously dependent on morphine.

Animals↗
PubMed1985

Morphine and clonidine oral self-administration: a study in morphine dependent or abstinent rats.

The ability of morphine and of clonidine to support self-administration has been evaluated in morphine dependent or abstinent rats, using an orally reinforced operant technique (F.R. 20). It was found that: Morphine drinking can function as a reinforcer of an operant response both in dependent and abstinent rats. The bitter taste of morphine becomes a secondary reinforcer for rats usually working for the alkaloid. Clonidine supports oral self-administration in morphine abstinent, but not in morphine dependent rats. The data are in line with clinical findings and give a further evidence that oral self administration in rats can be an useful model for the analysis of drug dependence.

Animals↗
PubMed1984

Stimulus properties of clonidine in chronically morphine treated rats trained to a morphine-saline discrimination.

In an operant behavior procedure of lever pressing on an FR 10 schedule of food reinforcement, morphine dependent and nondependent rats were trained to respond on a lever on one side of the food tray after a morphine (10 mg/kg i.p.) injection and to respond on a lever on the alternate side after a saline injection. Following discrimination training, in both dependent and nondependent rats saline was generalized to various doses of clonidine (10, 30 and 50 micrograms/kg i.p.). A response inhibition of about 65% was obtained with the highest dose. It was concluded that, even if clonidine can suppress signs of narcotic withdrawal, the internal state induced by morphine in an abstinent rat does differ from the one induced by clonidine in the same animal.

Animals↗
PubMed1983

Long-term sensitization to the excitatory effects of morphine. A motility study in post-dependent rats.

Motility effects of excitatory and depressant doses of morphine were studied in naïve, dependent (20 mg/kg daily) and post-dependent (about 40 days after withdrawal) rats. Doses of 0.6 and 1.25 mg/kg of morphine produced a greater increase in activity in post-dependent than in naïve rats. A 20-mg/kg dose exerted an excitatory effect in dependent rats instead of the depressant one induced in naïve animals. This excitatory effect was still evident but less pronounced in post-dependent rats. The dose of 1.25 mg/kg was repeatedly challenged in post-dependent (80 mg/kg daily) rats. It was found that the increased excitatory effect of this dose persisted unchanged 160 days after ceasing treatment. The present results demonstrate that several months after the withdrawal of morphine, sensitization still exists to the excitatory effect of the drug while tolerance to the depressant action is slight or no longer present shortly after ceasing treatment.

Animals↗
PubMedDate not supplied

Previous treatment with morphine and sensitization to the excitatory actions of opiates: dose-effect relationship.

The stimulatory effect of morphine on locomotor activity has been shown to be largely modified in rats that have been formerly dependent on this drug. In the present study, the relationship between the chronic dose of morphine and the degree of sensitization to the excitatory effect of opiates was investigated. To this end, four groups of rats were treated daily for 30 days with 1.25, 5, 20 and 80 mg/kg of morphine (i.p.) and challenged with morphine (1.25 and 2.5 mg/kg) or fentanyl (40 and 80 micrograms/kg) 1-4 months after ceasing the treatment. Drug-induced hypermotility in post-dependent rats appeared to be linearly related to the dose of the preceding chronic treatment after test doses of both morphine and fentanyl. The results are discussed in terms of a persistent dose-related modification of the neuronal mechanism subserving the excitatory component of the action of opiates; such a modification might offer a neurobiological basis for the fact that "relapse tendencies" for opiates persist for a long time after withdrawal.

Animals↗