ABSTRACT
The influence of peripheral benzodiazepine receptor ligands Ro5-4864 (0.05 or 1.0 mg/kg, i.p.) or PK11195 (0.05 or 1.0 mg/kg, i.p.) on the anxiolytic effect of ethanol (1.2 g/kg; 14% p/v; i.p.) was investigated in rats tested on the elevated plus-maze. Other animals were injected through intrahippocampal administrations of the ligands (0.5 or 1.0 nmol/0.5 &mgr;l) before ethanol (1.2g/kg; 14% p/v; i.p.) and submitted to the elevated plus-maze test. The results showed that the systemic administration of either ligands 24 hours before the ethanol treatment resulted in a reduced anxiolytic effect of this drug. Only PK11195 reversed the effect of ethanol after intrahippocampal injection. These data suggest that peripheral benzodiazepine receptors play a role in ethanol anxiolysis.
ABSTRACT
In vivo treatment of mice with peripheral benzodiazepine receptor ligands exerts an inhibitory effect on the inflammatory response in two models of acute inflammation. In the first model, pretreatment of the animals (24 h) with 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) and 7-chloro-5-(4-Chlorophenyl)-1, 3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2 (Ro5-4864), at different doses (0.00001-10 mg/kg, i.p.) dose dependently inhibited the formation of mouse paw oedema induced by carrageenan with mean ID(50s) of 0.009 (95% confidence limits=0.0076-0.013) and 0.04 (95% confidence limits=0.025-0.0086) mg/kg, respectively. Both ligands (0. 1 mg/kg, i.p.) inhibited in the same way the mouse paw oedema induced by carrageenan in animals with and without adrenal glands. PK11195 and Ro5-4864 (0.1 mg/kg, i.p.) inhibited the mouse paw oedema induced by several inflammatory mediators. In the second model, the pretreatment (24 h) with peripheral benzodiazepine receptor ligands (0.1 mg/kg, i.p.) exerted an inhibitory effect on neutrophil influx and produce a marked inhibition of carrageenan-produced interleukin-13 and interleukin-6 in pleural exudation. Our results extend previous findings that peripheral benzodiazepine receptor is involved in the inflammatory response, and suggest that this action may be linked to the action of different inflammatory mediators, probably mainly by the inhibition of the release of pro-inflammatory cytokines.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Antineoplastic Agents/pharmacology , Benzodiazepinones/pharmacology , Hypolipidemic Agents/pharmacology , Isoquinolines/pharmacology , Receptors, GABA-A/drug effects , Animals , Anti-Inflammatory Agents/therapeutic use , Disease Models, Animal , Inflammation/chemically induced , Inflammation/drug therapy , Interleukin-13/metabolism , Interleukin-6/metabolism , Male , Mice , Receptors, GABA-A/metabolismABSTRACT
This study investigates the anti-inflammatory effects of 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide and 7-chloro-5-(4-chlorophenyl)-1, 3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2-one in paw oedema induced by carrageenan in mice. Pretreatment (24 h) with both ligands inhibited oedema formation in at different doses (0.00001-10 mg/kg, i.p.) with range of inhibition of 25% to 70%, in animals with or without adrenal glands. These results demonstrate, for the first time, an in vivo anti-inflammatory property of peripheral benzodiazepine receptor ligands.
Subject(s)
Inflammation/prevention & control , Receptors, GABA-A/physiology , Adrenalectomy , Animals , Anti-Inflammatory Agents/pharmacology , Benzodiazepinones/pharmacology , Carrageenan , Dose-Response Relationship, Drug , Edema/chemically induced , Edema/prevention & control , Hindlimb/pathology , Inflammation/physiopathology , Injections, Intraperitoneal , Isoquinolines/pharmacology , Male , MiceABSTRACT
Endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was examined in several areas of the central nervous system (CNS) as well as in the immune and endocrine tissues of rats chronically treated with morphine and submitted to naloxone-induced withdrawal. A specific fluorogenic substrate was used to determine the endopeptidase 22.19 activity. A non-uniform increase in endopeptidase 22.19 activity was detected in the CNS. The highest increase in endopeptidase 22.19 specific activity was found in the dorsal hippocampus (about 3.5-fold higher than control), followed by occipital and frontal cortex, substantia nigra, thalamus and hypothalamus. In peripheral tissues, a significant decrease of endopeptidase 22.19 was observed in the pineal gland, whereas the morphine withdrawal syndrome caused a slight but significant increase in lymphoid tissues such as lymph nodes and thymus. These findings are indicative of a possible participation of endopeptidase 22.19 in naloxone-induced withdrawal.