Biomedical subjects

G Patrini

Publications and source records attributed to G Patrini.

At least 19 recordsLinked to original sources

PubMed1998

Cannabinoid-precipitated withdrawal: a time-course study of the behavioral aspect and its correlation with cannabinoid receptors and G protein expression.

To characterize the time course of the behavioral and biochemical aspects of the cannabinoid withdrawal syndrome, we injected the cannabinoid antagonist SR141716A (5 mg/kg i.p.) in rats made tolerant to CP-55,940 (0.4 mg/kg i.p., twice daily for 6.5 days), 1, 24 and 96 h after the last CP-55,940 injection. Because the CB1 receptor and G protein alpha subunit are involved in cannabinoid tolerance, we observed their changes throughout the brain during the withdrawal syndrome by use of in situ hybridization. In vehicle-pretreated rats SR141716A per se induced abnormal behavior significantly different from the vehicle group: wet dog shakes, forepaw fluttering and scratching. These signs remained significantly elevated even after the second and third antagonist doses. SR141716A significantly modified the mRNA levels of G alpha s and G alpha i subunits in some brain areas without affecting CB1 receptor and G alpha o expression. These findings led us to conclude that SR141716A may have intrinsic activity. Concerning cannabinoid withdrawal, the first SR141716A injection in tolerant rats resulted in behavioral signs different from those observed with the antagonist alone; this moderate withdrawal syndrome was characterized by turning, chewing and digging. Additional SR141716A doses 24 and 96 h later did not induce a significant abstinence syndrome. In situ hybridization after the first SR141716A injection showed that CB1 receptor and G protein alpha subunits, whose levels were low in tolerance, recovered their basal level of expression. Thus, the general desensitization of the cannabinoid receptor and of the transduction system in tolerance are recovered in abstinent rats and might be part of the molecular mechanisms underlying cannabinoid dependence.

Animals↗

PubMed1997

Changes in rat spleen cannabinoid receptors after chronic CP-55,940: an autoradiographic study.

We examined whether cannabinoid receptor density changes in the rat spleen after in vivo chronic exposure to cannabinoids. Rats received daily injections of 0.4 mg/kg IP of the synthetic cannabinoid receptor ligand CP-55,940 for 11 days. One h after the last injection on day 11, the rats were killed and spleen coronal sections were processed for receptor binding autoradiography with 10 nM of [3H]CP-55,940 in the absence or presence of unlabeled CP-55,940 (10 microM). Densitometric analysis of the autoradiograms showed significant loss of [3H]CP-55,940 binding of about 42% in chronic cannabinoid-treated, tolerant rats. Our findings indicate that cannabinoid receptors basically present in immune spleen cells are down-regulated by chronic exposure to cannabinoids, suggesting a role in immune modulation and in the impairment of immune function.

Animals↗

PubMed1997

Regulation of immune functions in rat splenocytes after acute and chronic in vivo treatment with CP-55,940, a synthetic cannabinoid compound.

Changes in mitogen-induced splenocyte proliferation and NK activity were evaluated after acute (1 h) and chronic (6 d) in vivo treatment of rats with the synthetic cannabinoid compound CP-55,940. At a dose of 0.4 mg/kg i.p. it significantly inhibited the splenocyte proliferative response to PHA and NK activity but half this dose (0.2 mg/kg) had no effect on immune responses. Pretreatment of rats with the cannabinoid receptor CB1 antagonist SR141716A did not antagonize the CP-55,940-induced immunosuppression, excluding the activation of this receptor subtype in the mediation of this effect. When immune function studies were done on rats tolerant to CP-55,940-induced analgesia, full tolerance also developed for the inhibition of splenocyte proliferation and NK activity. The data provided indicate that CB1 cannabinoid receptors are not involved in mediating the acute and chronic effects of cannabinoids on the immune system and suggest a possible implication of CB2 receptor although other modalities of CP-55,940 action can not be ruled out.

Animals↗

PubMed1997

Chronic treatment with a synthetic cannabinoid CP-55,940 alters G-protein expression in the rat central nervous system.

Prolonged exposure of rats to the synthetic cannabinoid receptor ligand, CP-55,940 (0.4 mg/kg, i.p. for 11 days), induced tolerance to analgesia, to the reduction in spontaneous locomotor activity and the incidence of splayed hind limbs. One hour after the last injection on day 11, the rats were killed and in situ hybridization was used to investigate the effect of treatment on G-protein alpha-subunit expression throughout the brain. Chronic cannabinoid exposure markedly reduced G alpha(s), G alpha(i) and G alpha(o) mRNA levels. The message for the alpha(s)-subunit was decreased in all the brain areas containing the basal autoradiographic signal; the decrease ranging from 25% in the thalamus to 45% in the mesencephalon. Also the basal G alpha(i) expression was reduced in tolerant rats showing the greatest decrease in the forebrain (63%) in the cerebellum (58%) and in the mesencephalon (38%). The reduction in G alpha(o) expression (25%) was more localized, being present only in the rostral portion of the brain (cortex, striatum and olfactory area). The alterations in alpha-subunits gene expression were not followed by any change in the amount of proteins. Our results indicate that, besides the receptor modification, alteration to the G-protein expression could be a molecular event associated with the development of cannabinoid tolerance.

Analgesics↗

PubMed1996

Changes in opioid receptor density on murine splenocytes induced by in vivo treatment with morphine and methadone.

In a 24-hr time course study we reported previously that a single systemic injection of morphine profoundly affected various immune parameters in mice. In the present study we examined whether these effects are mediated by changes in opioid receptor density on murine splenocytes after acute in vivo morphine (20 mg/kg s.c.) and methadone (12.5 mg/kg s.c.) at equianalgesic doses. To define the splenocyte subpopulations we used flow cytofluorimetric analysis with specific fluorescent monoclonal antibodies and calculated the binding of the fluoresceinyl opiate antagonist naloxone on opiate receptors. Both morphine and methadone reduced the density of opiate receptors on B- and T-lymphocytes. Specifically, 20 min, 1 and 3 days after the injection there was a marked reduction (about 55%) in naloxone binding sites; these returned to base line after 5 days for T-lymphocytes and after 7 days for B-lymphocytes. Despite the low proportion of macrophages among total splenocytes (about 10%), our results also indicate a tendency to a reduction in opiate receptor density also in the macrophage population. These findings indicate that a single exposure to morphine and methadone results in a strong, lasting down-regulation of opiate binding sites in murine splenocytes, probably accounting for the immunomodulation induced by opiates.

Analgesics, Opioid↗

PubMed1995

Morphine withdrawal syndrome and G protein expression: a study of the time course in the rat central nervous system.

We followed the changes in G protein alpha subunit expression and levels throughout the brain during the naltrexone-precipitated withdrawal syndrome in morphine-dependent rats. Intraperitoneally injected naltrexone (10 mg/kg) in rats made tolerant to morphine resulted in sustained withdrawal. Additional naltrexone doses 6, 24 and 72 h later still induced a significant abstinence syndrome. At the fifth naltrexone injection (8 days later) counted signs were completely resolved but checked ones were not. Besides the behavioural modifications, opiate withdrawal affected G protein expression in the central nervous system. In situ hybridization showed that G alpha s and G alpha o mRNA, whose levels are increased in tolerance, changed further during opiate withdrawal. Specifically, as alpha s mRNA in the hypothalamus was reduced after the first naltrexone injection and reached the control level with subsequent doses. However, alpha a mRNA expression in the olfactory system remained elevated after repeated naltrexone injections, declining to the control value of only after the fifth dose. The amounts of G alpha s and G alpha o protein closely followed the time course of mRNA. The relationship between behavioural and biochemical parameters is discussed, together with the regional selectivity of the modifications.

Animals↗

PubMed1995

Heterozygosity for homocysteinuria: a detectable and reversible risk factor for pulmonary thromboembolism.

Heterozygosity for homocysteinuria is a common, inherited autosomal condition that has recently been considered as an independent cardiovascular risk factor. In vitro and in vivo results suggest that this condition, like the homozygous form, is also a risk factor for deep-venous thrombosis and pulmonary thromboembolism. We report a case of recurrent pulmonary thromboembolism in a young woman with familial hyperhomocysteinaemia. The relative frequency of this condition, as well as its simple and harmless cure, make testing for heterozygosity for homocysteinuria useful and profitable in the prevention of pulmonary thromboembolism, above all in younger subjects with a significant case history.

Adult↗

PubMed1995

International guidelines and educational experiences in an out-patient clinic for asthma.

In June 1989, an out-patient clinic for asthma was instituted at Crema Hospital, Italy. Up to November 1994, 430 adult asthmatics were recruited, classified and managed according to the recommendations of the international guidelines. The aims of this study are to verify: 1) whether the organization of the clinic could maintain asthma under control and reduce hospital admissions; and 2) whether the traditional educational approach could be implemented by lessons in the school of asthma to improve the control of asthma symptoms and/or admissions. The data reported refer to the first 360 asthmatics attending the clinic between 1989 and 1994: 53, 45 and 2% of them were suffering from extrinsic, intrinsic and occupational asthma, respectively. On recruitment, forced expiratory volume in one second (FEV1) was < 80% of predicted in 170 patients, and arterial oxygen tension (Pa,O2) 8.0 kPa (< 60 mmHg) in 27 patients. After the admission visit, 190 patients (53%) were classified as mild, 97 (27%) as moderate, and 73 (20%) as severe asthmatics. In May 1993, a school of asthma was organized. Forty four patients were recruited, stratified according to the severity of their asthma and randomized into two groups: 22 patients attended the school, and 22 patients did not. Each group consisted of 5, 10 and 7 patients with mild, moderate and severe asthma, respectively. The school comprised four lessons twice a week. One year after the end of the school, we could find no differences between the two groups (school versus controls) with regard to the number of urgent care visits (9 vs 9), scheduled visits (22 vs 21) and hospital admissions (2 vs 2).

Adult↗

PubMed1994

Chronic CP-55,940 alters cannabinoid receptor mRNA in the rat brain: an in situ hybridization study.

Using in situ hybridization we found that chronic treatment with CP-55,940 (0.4 mg kg-1, i.p. daily for 11 days), a synthetic cannabinoid receptor ligand, changed cannabinoid receptor mRNA levels in rat brain. CP-55,940 produced the expected tolerance: the decrease in locomotor activity (75%) caused by an acute dose was diminished to 25% after the 11 days of treatment. Thirty minutes after the last injection the animals were killed and in situ hybridization indicated that the levels of cannabinoid receptor mRNA in the caudate-putamen were reduced by 33%, with no alteration in the other brain areas. We suggest that the altered cannabinoid receptor expression is part of the adaptive changes underlying cannabinoid tolerance.

Animals↗

PubMed1994

Effect of chronic exposure to naltrexone and opioid selective agonists on G protein mRNA levels in the rat nervous system.

The in situ hybridization technique was used to investigate the effect on G protein alpha subunit expression throughout the brain of rats chronically infused with naltrexone (70 micrograms/microliters, 1 microliter/h), DAGO (0.5 micrograms/microliter, 1 microliter/h), DADLE (11.4 micrograms/microliters, 1 microliter/h), DPDPE (3.4 micrograms/microliters, 1 microliter/h) and U-50,488H (4 micrograms/microliters, 1 microliter/h). Prolonged exposure to naltrexone did not modify G protein alpha subunit mRNA expression, whereas DADLE and U-50,488H, respectively, increased the levels of alpha s and alpha o mRNA in specific brain regions. In particular, a 15% increase in alpha s expression was only observed in the dorsomedial hypothalamic nucleus of rats undergoing chronic DADLE infusion: a 15% increase in alpha o levels was detected in the claustrum and endopiriform nucleus of rats chronically treated with U-50,488H. These are the first in vivo data to demonstrate that only chronic stimulation with an opioid agonist (morphine and/or DADLE and U-50,488H) is capable of modifying G protein alpha subunit mRNA. The regional selectivity of these modifications is discussed, together with the receptor specificity of the opioid effects.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1994

Effect of morphine and methadone acute treatment on immunological activity in mice: pharmacokinetic and pharmacodynamic correlates.

This report describes the 24-hr time course of the immunomodulatory effects of an acute s.c. injection of morphine in C57BL6 mice, and correlates these effects with the drug's analgesic properties and serum levels. Acute morphine treatment had a biphasic effect on various immune parameters: there was an increase in in vitro phagocytosis and the killing of Candida Albican cells by peritoneal polymorphonuclear leukocytes 20 and 40 min after the injection of morphine, 20 mg/kg, when analgesia and serum morphine concentrations were at their peak. Interestingly, 24 hr after morphine administration (when antinociception and morphine blood levels were no longer detectable) these parameters underwent a marked reduction. Similarly, macrophage-mediated inhibition of tumor cells proliferation was first stimulated (at 20 and 40 min) and then depressed (at 24 hr). Splenic natural killer cell cytotoxicity, determined by standard 51Cr release from YAC-1 target cells, also was evaluated. No differences in natural killer activity was observed at any of the monitored time points. In addition, we evaluated the immunomodulatory effects of an acute injection of methadone (a synthetic narcotic compound) at a dose inducing the same degree of analgesia as morphine. None of the tested immunoparameters were affected by the administration of methadone, which indicates the different drug-sensitivity of immunological correlates in vivo.

Animals↗

PubMed1993

In situ hybridization reveals specific increases in G alpha s and G alpha o mRNA in discrete brain regions of morphine-tolerant rats.

In situ hybridization histochemistry has been used to detect the basal distribution of mRNA encoding the alpha subunit of Gs, Go and Gi2 proteins throughout the rat brain. Based on these data we investigated the effect of chronic morphine on the content of these G protein alpha subunits mRNA. We observed an increase in the expression of alpha s and alpha o messages of chronically morphine-treated animals, while no changes were seen in alpha i2 mRNA. Specifically a 30% increase in expression for alpha s was seen only in the paraventricular nucleus of hypothalamus and a 20% elevation for alpha o was detected in the claustrum and endopiriform nucleus. Immunoblotting analysis was used to correlate the changes in alpha s and alpha o messages with equivalent changes in protein levels. Chronic morphine significantly increased alpha s amounts in the hypothalamus (70%), and produced a minor elevation (30%) in G alpha o levels in the olfactory area. Our results indicate that in discrete brain regions altered G protein expression is part of the adaptive changes underlying opiate tolerance.

Animals↗

PubMed1992

Further investigations on the antipropulsive effect of centrally administered histamine and its relation with morphine.

The effect of intracerebroventricularly (i.c.v.) administered histamine (100 micrograms/rat) on intestinal myoelectrical activity was investigated in the jejunum of fasted rats. Histamine caused the disappearance of phase III and a partial reduction of phase II of migrating myoelectric complexes. This effect was antagonized by i.c.v. pretreatment with mepyramine (10 micrograms/rat), an H1 receptor antagonist. Lesions of central noradrenergic neurons by i.c.v. injection of the neurotoxin 6-hydroxydopamine strongly reduced both the inhibition of intestinal propulsion and the migrating myoelectric complexes profile induced by i.c.v. histamine, whereas pretreatment with p-chlorophenylalanine, a selective depletor of serotonin stores, had no effect. It thus appears that aminergic pathways are involved in the visceral effects of central histamine. Mepyramine (200 micrograms/rat i.c.v.) partially reduced the slowing of intestinal transit induced by high doses of morphine. Pretreatment with compound 48/80 (10 micrograms/rat i.c.v.), a mast cell degranulator, but not with alpha-fluoromethylhistidine, an irreversible inhibitor of histidine decarboxylase, reduced the antipropulsive action of i.c.v. morphine to the same extent as mepyramine, suggesting that histamine released from cerebral mast cells by high doses of morphine could contribute to the intestinal inhibition by morphine.

Animals↗

PubMed1991

Pertussis toxin pretreatment affects opiate/nonopiate and stress-induced analgesia differently.

Intracerebroventricular injection of pertussis toxin (PTX, 1 microgram/rat) six days before the hot plate test abolished analgesia induced by central morphine. The toxin did not affect analgesia evoked by central neurotensin or ASU 1-7 eel calcitonin. PTX pretreatment also attenuated footshock-induced analgesia (FSIA) delivered to all four paws. When the shock was restricted to the front paws, PTX consistently lowered postshock tail flick latencies, but did not reduce analgesia resulting from shock delivered to the hind paws. It thus appears that PTX-sensitive G-proteins are an essential transduction step needed to initiate the molecular events underlying opiate analgesia evoked by either morphine or shock. In contrast, the signal transduction mechanism subsequent to the stimulation of neurotensin or calcitonin receptors, and to the nonopiate FSIA, appears not to involve PTX-sensitive G-proteins.

Animals↗

PubMed1990

Pertussis toxin modifies the effect of central morphine on rat intestinal motility.

To find whether the antipropulsive effect of morphine administered intracerebroventricularly (i.c.v.) depends on a G-protein-mediated mechanism, we studied the effect of i.c.v. pertussis toxin (PTX) pretreatment on morphine-induced inhibition of intestinal motility. The influence of PTX was evaluated on intestinal transit (charcoal meal test) and by monitoring of intestinal myoelectrical activity. The antitransit effect of morphine (10 micrograms/rat) was antagonized by about 70% 3, 6, 9 and 12 days after PTX pretreatment (1 microgram/rat) and it was partially restored after 25 days. I.c.v. morphine abolished the regular appearance of the myoelectric migrating complex (MMC) recorded in the rat jejunum and this effect was completely antagonized by PTX pretreatment. When morphine was injected 25 days after PTX, it significantly reduced MMC frequency, confirming the partial recovery seen in the transit experiments. The pertussis toxin-catalyzed ADP ribosylation of a 39-41 kDa substrate in membranes prepared from hypothalamus and midbrain of rats injected with toxin 6 days before was strongly reduced as compared to the controls. On the contrary, after 25 days, ADP ribosylation was the same in treated and control rats. Thus the antipropulsive effect of central morphine could be initiated at receptor sites which interact with G-protein substrates of pertussis toxin.

Adenosine Diphosphate↗

PubMed1990

Pertussis toxin inhibits morphine analgesia and prevents opiate dependence.

Six days after intracerebroventricular pretreatment of rats with pertussis toxin (PTX 0.5 microgram/rat) there was a marked decrease in the antinociceptive effect of morphine, regardless of the route of opioid administration (into the periaqueductal gray matter, intrathecally or intraperitoneally) or the analgesic test used (tail flick and jaw opening reflex). PTX pretreatment also partially attenuated the naloxone-precipitated withdrawal syndrome in morphine-dependent rats, significantly reducing teeth chattering, rearing and grooming. These in vivo findings indicate that G-protein-dependent mechanisms are involved in morphine analgesia and dependence. The biochemical mechanism could be related to ADP ribosylation of Gi coupled to the adenylate cyclase system, but an interaction of PTX with other G-proteins linked to different second messengers or directly to ionic channels cannot be excluded.

Adenylate Cyclase Toxin↗

PubMed1989

[Clinico-laboratory evaluation a new sustained-release preparation of anhydrous theophylline].

The clinical effectiveness and the pharmacokinetic parameters of a once-a-day sustained release preparation of anhydrous theophylline were studied in a trial carried out on 10 adult patients affected by bronchial asthma or chronic obstructive lung disease. Treatment with this new theophylline preparation allowed us to obtain mean serum concentrations within the therapeutic range (5-20 mcg/ml) which remained quite constant during 24 hours. All patients evidenced improvement of dyspnea and of the signs of bronchospasm. Tolerability was very good.

Adult↗

PubMed1989

Histamine as a central modulator of rat intestinal transit.

Histamine (HA) injected i.c.v. to rats inhibited intestinal propulsion in linear relation to the log of the administered doses (in the range from 20-100 micrograms/rat). In the same dose range HA also induced a dose-related analgesic effect (tail-flick test). The dose of HA maximally active by the i.c.v. route (100 micrograms/rat) showed neither of these effects when injected i.v. or i.p. HA-induced intestinal inhibition and analgesia were antagonized competitively by i.c.v. mepyramine (10 micrograms/rat), an H1 receptor antagonist, whereas cimetidine (10 micrograms/rat), an H2 receptor antagonist, had no effect. Repeated i.c.v. injections of HA resulted in tachyphylaxis of both intestinal inhibition and analgesia. Pretreatment with i.c.v. naloxone (20 micrograms/rat) antagonized the antipropulsive effect of HA in a noncompetitive fashion, but did not affect its antinociceptive action. The relevance of the central histaminergic system in the modulation of gastrointestinal motility and its relationship with the opioid system are discussed.

Analgesia↗