Seasonal rhythm of red pigment concentrating hormone in the crayfish.

The content of red pigment concentrating hormone (RPCH) in the eye-stalk of the crayfish Procambarus clarkii varies seasonally, with maximum values during the summer months and the lowest values in winter. The responsiveness of tegumentary chromatophores to synthetic RPCH varies concurrently.

Carbachol-induced inositol phosphate formation in rat striatum is mediated by both M1 and M3 muscarinic receptors.

In vibratome-cut slices from rat striatum and in the presence of 10 mM LiCl, the cholinergic agonist carbachol stimulated the accumulation of total [3H]inositol phosphates (EC50 11+/-1 microM and maximum effect 546+/-36% of basal). The response to 100 microM carbachol (497+/-24% of basal) was inhibited by muscarinic antagonists (1 microM), the rank order of efficacy being 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 100% inhibition) approximately pirenzepine (98+/-3%) > p-fluoro analog of hexahydro-sila-difenidol (pFHHSiD; 90+/-3%) >> methoctramine (32+/-7%) approximately tropicamide (30+/-10%). Antagonist inhibition curves best fit to a single-site model for 4-DAMP (pKi 8.9+/-0.2) whereas, for both pirenzepine and pFHHSiD, the best fit was to the two-site model. The pKi values for the high-affinity (8.3+/-0.2) and low-affinity (6.9+/-0.2) components for pirenzepine-mediated inhibition corresponded to those reported for M1 and M3 receptors, respectively. The pKi values for the high-affinity (8.2+/-0.3) and low-affinity (7.0+/-0.2) components for pFHHSiD inhibition were in good agreement with those reported for M3 and M1 receptors, respectively. Altogether these results indicate that carbachol-induced [3H]inositol phosphate formation in rat striatal slices is mediated by both M1 and M3 muscarinic receptors.

Muscarinic M1 and M3 receptors in rat striatum: a binding study.

In this study, the authors set out to determine the presence of M3 muscarinic receptors in rat striatum by examining the binding of [3H]N-methylscopolamine ([3H]NMS) to striatal membranes and its displacement by antagonists with different affinity for M1 and M3 muscarinic receptors -pirenzepine; 4-diphenylacetoxy-N-methylpiperidine methiodide, 4-DAMP; and the p-fluoro analog of hexahydro-sila-difenidol, pFHHSiD). The specific binding of [3H]NMS to membranes from rat striatum (551 +/- 40 fmol.mg prot.-1, KD 0.11 +/- 0.01 nM) was displaced in a concentration-dependent manner by all three antagonists tested. Inhibition curves best fit to a single-site model for 4-DAMP (pKi 9.1 +/- 0.1), whereas for both pirenzepine and pFHHSiD, the best fit was to the two-site model. The pKi values for the high-affinity (8.0 +/- 0.2) and low-affinity (6.7 +/- 0.2) components for pirenzepine-mediated inhibition of [3H]NMS binding corresponded to those reported for M1 and M3 receptors, respectively. The pKi values for the high-affinity (7.7 +/- 0.1) and low-affinity (7.1 +/- 0.2) components for pFHHSiD inhibition were in good agreement with those reported for M3 and M1 receptors, respectively. Altogether, these results indicate the presence in rat striatum of both M1 and M3 muscarinic receptors. These findings might be relevant to the design and use of muscarinic antagonists in the treatment of neurological disorders such as Parkinson's disease.

Functional characterisation of alpha 1-adrenoceptor subtypes mediating noradrenaline-induced inositol phosphate formation in rat thalamus slices.

In cross-chopped slices from rat thalamus and in the presence of 10 mM LiCl, noradrenaline stimulated the accumulation of [3H]inositol phosphates with [3H]inositol monophosphates ([3H]IP1) being the major product detected (86 +/- 2% of total [3H]inositol phosphates). Noradrenaline-induced [3H]IP1 accumulation was concentration-dependent and yielded and EC50 of 4.6 +/- 0.2 microM, maximum effect of 272 +/- 3% of basal formation and Hill coefficient (nH) of 1.6 +/- 0.1. The effect of 100 microM noradrenaline was inhibited by the alpha 1-adrenoceptor antagonists prazosin, (+)-niguldipine, 5-methylurapidil and WB-4101 (2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4-benzodioxane). The inhibition curve for prazosin best fit to a single-site model whereas curves for (+)-niguldipine, 5-methylurapidil and WB-4101 best fit to a two-site model. The putative alpha 1D-adrenoceptor-selective antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8- azaspiro[4.5]decane-7,9-dione) showed low potency and efficacy to inhibit the response to noradrenaline. Pre-treatment of the slices with chloroethylclonidine (100 microM; 30 min) decreased by 64 +/- 4% the maximum response. Noradrenaline-induced [3H]IP1 accumulation was significantly reduced by Ca2+ removal (by 64 +/- 2%) and by the Ca(2+)-channel blockers Ni2+, Co2+ and nimodipine (inhibition of 56 +/- 6%, 54 +/- 5% and 41 +/- 5%, respectively). Taken together these results indicate that noradrenaline-induced inositol phosphate formation in thalamus slices is mainly mediated by the activation of both alpha 1B and alpha 1A subtypes of alpha 1-adrenoceptors.

Carbachol stimulates inositol phosphate formation in rat thalamus slices through muscarinic M3-receptor activation.

In cross-chopped slices from rat thalamus and in the presence of 10 mM LiC1, the cholinergic agonist carbachol stimulated the accumulation of total [3H]inositol phosphates ([3H]IP2 = [3H]IP1 + [3H]IP2 + [3H]IP3). Best-fit values for the concentration-response curve for carbachol after 60 min incubation yielded an EC50 of 44 +/- 6 microM, maximum effect of 199 +/- 6% of basal accumulation and Hill coefficient (nH) of 1.1 +/- 0.1. Carbachol-induced [3H]IPs accumulation was inhibited by 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; pKi 9.1) and the p-fluoro analogue of hexahydro-sila-difenidol (pF-HHSiD; pKi 8.1). Concentration-response curves for carbachol were shifted to the right in a parallel fashion by pirenzepine (100, 300 and 100 nM). A Schild plot of the data was linear (slope 0.95 +/- 0.04) and yielded a log KD for pirenzepine of -6.8 +/- 0.1. Taken together, these results suggest that carbachol-induced inositol phosphate accumulation in rat thalamus is mediated by muscarinic M3-receptors.

Intracerebral infection of Cebus apella with the XJ-Clone 3 strain of Junín virus.

To assess the usefulness of the South American primate Cebus apella as a model for neurovirulence of Junín virus, eight monkeys were inoculated with 10(5) LD50 of the attenuated XJ-Clone 3 Junín virus strain by the intrathalamic route. After the second week, weight loss and polyadenopathies were observed in most animals, one-half of which had a transient leukothrombocytopenia. Moderate clinical central nervous system (CNS) involvement was present in four of eight monkeys, while the rest had only mild neurologic signs. All recovered except one, which developed a deep coma and was killed in a pre-mortem stage at 18 days post-infection (pi). Junín virus was isolated from the throat from five, from the blood from three, and from the brain from two monkeys. In the most severely ill animal, virus titers higher than viremia were detected in both inoculated and contralateral brain hemispheres, as well as in lung, lymph node, and small intestine. Junín antigens and "in vivo" bound immunoglobulins were detected by immunofluorescence (IF) in the brain of four animals at 18, 21, 40, and 155 days pi. Moderate lymphocytic parenchymal and meningeal infiltration were observed in the brain of four animals, and gliosis was also present in the most affected monkey. Although the clinical response to infection was not uniform, all infected monkeys developed high IF antibodies. Cebus apella cannot be used as a highly sensitive model for Argentine hemorrhagic fever (AHF). However, the results obtained show that the XJ-Clone 3 strain can replicate in the primate CNS and to induce lesions and immunoglobulin deposition. In addition, viral persistence is suggested by the late detection of viral antigens in brain at 40 and 155 days pi.

Human rheumatoid factor crossidiotypes. II. Primary structure-dependent crossreactive idiotype, PSL2-CRI, present on Wa monoclonal rheumatoid factors is present on Bla and other IgM kappa monoclonal autoantibodies.

The amino acid sequence of the L-CDR2 (complementarity-determining region) of Bla mRF (monoclonal rheumatoid factor) is identical to that of the Wa mRFs. The PSL2-CRI (crossreactive idiotype), as determined by anti-PSL2, which has been shown to be present on all Wa mRFs, is also present on the Bla mRF and other monoclonal autoantibodies. PSL2-CRI is, therefore, not unique to Wa mRFs and may be present on most IgM kappa monoclonal autoantibodies. Whether PSL2-CRI is a crossidiotype (XId) that is selectively present on autoantibodies or represents an allotypic marker for a V kappa III gene is undetermined.

Immunological studies in Rockland mice infected with T. cruzi. Development of antinuclear antibodies.

The existence of antinuclear antibodies (ANA) and their relationship with anti-Trypanosoma cruzi specific agglutinins was studied in Rockland mice inoculated with 10(5), 10(4) or 10(3) epimastigotes and 2 X 10(5) trypomastigotes of T. cruzi. ANA and anti-T. cruzi agglutinins were detected at the same time in groups of mice receiving 10(5) culture forms, while in those groups of mice receiving 10(4) parasites agglutinins were established earlier than ANA which were present only at low titres. Positive serology and ANA were also detected in mice infected with trypomastigotes. Neither specific agglutinins nor ANA were found in groups of mice receiving 10(3) parasites probably because the number of parasites inoculated was too low to infect them. ANA were not found in not infected mice. ANA induced in mice by T. cruzi infection seem to be related to the amount of parasites inoculated and thus with the degree of the subsequent infection. Immunopathologic studies carried out in mice infected with trypomastigotes showed the presence of nodular deposits of gamma globulin in the kidneys, suggesting the possibility of an immune complex disease : the light and electron microscopic studies of the kidneys showed in the glomeruli an increase of the mesangium, hypercellularity and thickened basement membranes.

Antiglobulins in ankylosing spondylitis.

An immunoadsorption technique was used to investigate the presence of antiglobulin factors in 28 patients with ankylosing spondylitis and 30 healthy individuals. Both groups were "sero-negative" by standard agglutination techniques. Whereas the controls were consistently negative, 18 of the 28 patients with ankylosing spondylitis had antiglobulins of the IgG class.