Multiple sigma binding sites in guinea-pig and rat brain membranes: G-protein interactions.

1. Evidence is accumulating for multiple sigma (sigma) sites in the mammalian CNS. 2. We have addressed this problem and have examined sigma site - G-protein coupling in guinea-pig and rat brain membranes. 3. Ditolylorthoguanidine (DTG), (+)-3-(3-hydroxyphenyl)-N-1-(propyl)piperidine (3PPP) and dextromethorphan displaced [3H]-DTG (3.4 nM) with low Hill slopes of 0.5, 0.6 and 0.6, respectively in guinea-pig brain membranes. 4. In the presence of 5'-guanylylimidodiphosphate (Gpp(NH)p; 100 microM), the specific binding of [3H]-DTG was reduced by 36.7%, the Hill slope of 3PPP was increased to near unity, the ability of dextromethorphan to displace DTG was virtually abolished and the Hill slope for DTG remained low (0.7), indicating the presence of at least two binding sites. These data indicate that although Gpp(NH)p removes a dextromethorphan high affinity site, two DTG selective sites remain in the presence of Gpp(NH)p. 5. The present study suggests that DTG binds to at least three sites in guinea-pig brain membranes, at least one of which is G-protein linked. 6. In rat brain membranes, DTG displaced itself (3.4 nM) with a Hill slope near 1. 3PPP displacement of [3H]-DTG was comparable with the guinea-pig (Hill slope 0.5) and displaced from more than 1 site. Dextromethorphan did not displace [3H]-DTG at concentrations below 10 microM. 7. The heterogeneity of sigma sites appears to be less in rat than in guinea-pig brain membranes.

The lack of utility of the rat vas deferens as a functional bioassay for sigma ligands.

The present study examined the utility of the rat vas deferens preparation as a bioassay for sigma site ligands. sigma Ligands such as (+/-)-pentazocine, phencyclidine (PCP) and (+)-SK&F 10047 potentiated neurogenic twitch contractions. However, neither the order of potency nor the absolute potency of (+/-)-pentazocine and (+)-SK&F 10047 correlated with their affinity at central sigma sites. Furthermore, another potent sigma ligand, ditolyl-ortho guanidine (DTG) neither affected neurogenic twitch contractions nor inhibited twitch potentiation by PCP or (+)-SK&F 10047 at concentrations up to 30 mumol/l. These data indicate that the rat vas deferens is not a useful bioassay for the evaluation of sigma ligands. PCP, (+)-SK&F 10047 and (+/-)-pentazocine probably enhance neurogenic contractions in rat vas deferens primarily by inhibition of the neuronal uptake of noradrenaline.

Action of gold salts in some inflammatory and immunological models.

Several gold salts were compared in kaolin-induced rat paw oedema, u.v. erythema in guinea pigs, delayed type hypersensitivity and humoral immunity in mice, and adjuvant-induced arthritis in the rat. In the latter the additional parameters of serum gold and copper levels and lysosomal enzyme activity were determined. In addition, the in vitro inhibition of several lysosomal enzymes derived from mouse macrophages was studied. The gold compounds examined were aurothiomalate, aurothioglucose, triethylphosphine gold chloride (SK & F 36914) and its glucopyranoside derivative (SK & F D-39162), triphenylphosphine gold chloride and sodium gold chloride dihydrate. SK & F 36914 and SK & F D-39162 has significant activity after oral dosage upon paw kaolin and u.v. erythema in rats and guinea pigs, respectively. Gastric swelling also occurred. In Wistar rats, adjuvant arthritis was little affected by the gold salts but in the Lewis rats there was suppression. In both strains there was less elevation in serum copper levels with treatment by SK & F 36914 and SK & F D-39162, but not by aurothiomalate. None of the compounds had any measurable effect on delayed hypersensitivity or humoral antibody levels in mice. The in vitro activities of cathepsin B1 and cathepsin D were inhibited by all the gold compounds. Reactivity of gold compounds with glutathione and cysteine in vitro was dependent on compound solubility and the nature of the gold ligand. Considerable differences exist between the profiles of activity for the different gold salts evaluated. These observations indicate that some gold salts do possess anti-inflammatory activity with a potency similar to that of indomethacin.

The biological properties of Org 6216, a new type of steroid with a selective local anti-inflammatory action.

11 beta-Hydroxy-16 alpha, 17 alpha, 21-trimethyl-pregna-1,4-diene-3,20-dione(ORG 6216) is a novel type of anti-inflammatory steroid which displays a dissociation of local from systemic effects in a range of animal models. Moreover, ORG 6216 is exceptional in that it has not shown any significant atrophogenic activity in the skin when administered either topically or intracutaneously in animal models.

Production of ultraviolet-light-induced skin erythema in the hairless rat: a comparison with the haired rat in screening for anti-inflammatory drugs.

The onset of this erythema in response to different times of exposure corresponds closely to that in the haired animal. Orally administered phenylbutazone (30 mg/kg) or subcutaneously administered fluocinolone acetonide (10 mg/kg) have an equivalent antierythemic effect on haired and hairless animals. The hairless rat may therefore be an attractive alternative to its haired counterpart in this model since, prior to irradiation, it requires no depilation--which itself may affect subsequent erythema production.