Suppression of adjuvant arthritis in rats with chronic bromocriptine treatment does not prevent associated oxidative stress

T helper cell immunity in pregnancy and influence on autoimmune disease progression

Pregnancy presents the maternal immune system with a unique immunological challenge since it has to defend against pathogens while tolerating paternal allo-antigens expressed by fetal tissues. T helper (Th) cells play a central role in modulating immune responses and recent advances have defined distinct contributions of various Th cell subsets throughout each phase of human pregnancy, while dysregulation in Th responses show association with multiple obstetrical complications. In addition to localized decidual mechanisms, modulation of Th cell immunity during gestation is mediated largely by oscillations in sex hormone concentrations. Aberrant Th cell responses also underlie several autoimmune disorders while pregnancy-induced changes in the balance of Th cell immunity has been shown to exert favorable outcomes in the progression Th1 and Th17 driven autoimmune conditions only to be followed by post-partal exacerbations in disease.

Anti-inflammatory effect of the ghrelin agonist growth hormone-releasing peptide-2 (GHRP-2) in arthritic rats

Chronic arthritis induces hypermetabolism and cachexia. Ghrelin is a gastrointestinal hormone that has been proposed as a treatment to prevent cachexia. The aim of this work was to examine the effect of administration of the ghrelin agonist growth hormone-releasing peptide-2 (GHRP-2) to arthritic rats. Male Wistar rats were injected with Freund's adjuvant, and 15 days later arthritic and control rats were daily injected with GHRP-2 (100 microg/kg) or with saline for 8 days. Arthritis induced an increase in serum ghrelin (P < 0.01) and a decrease in serum concentrations of leptin (P < 0.01), whereas GHRP-2 administration increased serum concentrations of leptin. GHRP-2 increased food intake in control rats but not in arthritic rats. However, in arthritic rats GHRP-2 administration ameliorated the external symptoms of arthritis, as it decreased the arthritis score (10.4 +/- 0.8 vs. 13.42 +/- 0.47, P < 0.01) and the paw volume. In addition, circulating IL-6 and nitrites/nitrates were increased by arthritis, and GHRP-2 treatment decreased the serum IL-6 levels (P < 0.01). To elucidate whether GHRP-2 is able to modulate IL-6 release directly on immune cells, peritoneal macrophage cultures were incubated with GHRP-2 or ghrelin, the endogenous ligand of the growth hormone (GH) secretagogue receptor. Both GHRP-2 (10(-7) M) and ghrelin (10(-7) M) prevented endotoxin-induced IL-6 and decreased nitrite/nitrate release from peritoneal macrophages in vitro. These data suggest that GHRP-2 administration has an anti-inflammatory effect in arthritic rats that seems to be mediated by ghrelin receptors directly on immune cells.

Daily profiles of plasma prolactin (PRL), growth hormone (GH), insulin-like growth factor-1 (IGF-1), luteinizing hormone (LH), testosterone, and melatonin, and of pituitary PRL mRNA and GH mRNA in male Long Evans rats in acute phase of adjuvant arthritis

We studied the effects of adjuvant arthritis (AA) on the endocrine circadian rhythms of plasma prolactin (PRL), growth hormone (GH), insulin-like growth factor-1 (IGF-1), luteinizing hormone (LH), testosterone, and melatonin and of pituitary PRL and GH mRNA in male Long Evans rats. Groups of control and AA rats (studied 23 days after AA induction) that were housed under a 12/12 h light/dark cycle (light on at 06:00 h) were killed at 4 h intervals starting at 14:00 h. Cosinor analysis revealed a significant 12 h rhythm in PRL and PRL mRNA (p < 0.001) in controls with peaks at 14:00 h and 02:00 h, respectively. The peak at 02:00 h was abolished in the AA group resulting in a significant 24 h rhythm in parallel with that of PRL (p < 0.05) and PRL mRNA (p < 0.0001). Growth hormone showed no rhythm, but a significant rhythm of GH mRNA was present in both groups (p < 0.0001). Insulin-like growth factor-1 showed a 24 h rhythm in control but not in AA rats. The mean values of GH, GH mRNA, and IGF-1 were significantly reduced in AA. Luteinizing hormone displayed a significant 24 h rhythm (p < 0.01) peaking in the dark period in the control but not AA group. Testosterone showed in phase temporal changes of LH levels with AA abolishing the 02:00 h peak. Melatonin exhibited a significant 24 h rhythm in control (p < 0.001) and AA (p < 0.01) rats with maximum levels during the dark phase; the mesor value was higher in the AA males. These results demonstrate that AA interferes with the rhythms of all the studied hormones except the non-24 h (arrhythmic) GH secretion pattern and the rhythm in melatonin. The persistence of a distinct melatonin rhythm in AA suggests the observed disturbances of hormonal rhythms in this condition do not occur at the level of the pineal gland.

Some aspects of Parasitology and Immunology in general Medicine

The objective of these studies is to review the role of some parasites and their components in inflammation, allergy and immune system. We also report recent results published by others group as well as our own.

A spectrum of antibody (IgG. IgG1, IgM) response in mice infected with trichinella spiralis treated with L-mimosine

The purpose of this study was to demonstrate the anti-inflammatory effects of L-mimosine on chronic inflammation, by investigating its effect on the immunological response of BALB/c mice infected with the nematode parasite Trichinella spiralis. Specific anti-parasite immunoglobulins (IgG, IgG1 and IgM) were detected by the ELISA method in the serum of both the treated and the untreated animals at different periods of time for 60 days post infection. Two groups consisting of 18 mice each were used. The mice were 6 weeks of age. Both groups were infected with 220 larvae (L1-T. spiralis) per os: one group was administered an intraperitoneal injection of L-mimosine (200 &mgr;g/100 ml/dose) for 27 days (the first injection started 7 days before infection) and the second group was administered an intraperitoneal injection of saline solution (100 &mgr;l/dose). Parasite specific IgG, IgG1 and IgM levels were determined in the sera of infected, untreated mice. The levels of IgG and IgG1 were increased following infection and remained elevated throughout the experimental period, while IgM was significantly decreased on the 50th day post-infection. These levels were found to be lower in the L-mimosine treated infected mice, compared to the untreated mice. The inhibition started from day 10 and continued until day 60. In healthy animals, the production of immunoglobulins was not measurable. Non-infected animals treated with L-mimosine also showed no detectable anti-parasite specific immunoglobulins.

Rat strain differences in responses of plasma prolactin and PRL mRNA expression after acute amphetamine treatment or restraint stress

1. The aim of this study was to compare the effects of acute amphetamine (AMPH) treatment and restraint stress on plasma level of prolactin (PRL) and PRL mRNA expression in the adenohypophysis in Sprague-Dawley and Lewis male rats, the latter known to have a deficient hypothalamo-pituitary-adrenal (HPA) axis. 2. Both restraint stress and AMPH treatment (i.p. in a dose of 8 mg/kg of b.w.) were applied 15 or 30 min before termination of the experiment. Plasma PRL and corticosterone (CORT) were determined by radioimmunoassay. PRL mRNA expression was estimated by a dot-blot hybridization. 3. Restraint stress and AMPH treatment induced a significant increase in the CORT plasma level, as an indicator of stress response. Compared to Sprague-Dawley rats, the magnitude of CORT increase after both stimuli was significantly lower in Lewis rats. 4. Although restraint stress significantly increased the PRL plasma levels in both rat strains, AMPH treatment reduced the PRL levels in both rat strains. However, the changes of PRL plasma levels had another pattern in Lewis rats than in Sprague-Dawley rats. Control plasma PRL levels were significantly higher in Lewis rats, and in this rat strain AMPH treatment for 30 min increased the PRL levels as compared to the values obtained after AMPH treatment for 15 min. 5. Expression of PRL mRNA in adenohypophysis by restraint stress and AMPH treatment had a similar pattern. After a 15-min lasting restraint stress, the expression of PRL mRNA was decreased insignificantly in both rat strains. AMPH treatment induced in Sprague-Dawley rats a significant decrease of PRL mRNA after a 15-min interval while after 30 min there was a significant increase. However, in Lewis rats AMPH failed to significantly change PRL mRNA. 6. The results from the present study indicate that the mechanisms mediating the effects of acute restraint stress and acute AMPH treatment differ in PRL response in Sprague-Dawley and Lewis male rat strains. Differences in the observed responses in Lewis rats could be related to the deficient activity of HPA axis in this rat strain.