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Nociceptive induced activation of exploratory behaviour: a role for ß-endorphin
No full textExamined the role of β-endorphin in the regulation of open-field behavior in 19 male rabbits during the formalin test. Sham-injected Ss showed no pain reactions. Formalin-injected Ss displayed short-lived reactions that appeared immediately after injection, gradually decreased during Trial 2 (1 wk after Trial 1 immediately after β-endorphin treatment), and never recurred in Trial 3 (10 min after treatment). Formalin increased locomotor activity and rearing, but this effect did not occur in anti-β-endorphin-treated Ss. Results suggest that moderate, short-lasting pain induces the release of β-endorphin, which in turn activates locomotor activity and rearing. The β-endorphin system seems to be crucial in facilitating behavioral coping mechanisms and in improving response patter
Effects of an anti-ß-Endorphin on tonic immobility in rabbits
No full textThe involvement of endogenous beta-endorphin (beta-EP) in tonic immobility (TI) was evaluated in rabbits following the intracerebroventricular (ICV) administration of a specific antibody. Rabbits were tested twice with a 1-week intersession interval. For each animal, results of Session 1 were used as the baseline. Six hours before the beginning of Session 2, a bilateral ICV injection of specific anti-beta-EP serum or aspecific gamma-globulin (vehicle) was performed. Results showed that pretreatment with anti-beta-EP serum increased TI duration, whereas no change occurred in the vehicle group. In a parallel experiment we evaluated TI duration in the presence of formalin pain: TI increased in animals pretreated with aspecific gamma-globulins and decreased in the animals pretreated with anti-beta-EP serum. Results suggest that the beta-EP system acts to limit TI duration, but that this effect is reversed by persistent pain
Hyperprolactinemia induces a decrease of beta-endorphinergic activity in the hypothalamus
No full textEffect of dopaminergic drugs on hypothalamic and pituitary immunoreactive beta-endorphin concentrations in the rat
No full textThermal damage processes follow kinetic governing relations and resultant damage depends on both temperature and time of exposure. Application to models of cardiac ablation depends on identification of a quantitative measure of thermal damage. Loss of the native state birefringence of myocardium is one such measure. Damage data derived from short term Argon laser exposure and long term heated block experiments were adapted to model middle term heating as in cardiac ablation. Model predictions from the estimated coefficients compare favorably to the experimental observations; however, much remains to be learned about the true kinetic nature of the damage processes in this tissue
Mainly mu-opiate receptors are involved in luteinizing hormone and prolactin secretion
No full textWe evaluated plasma PRL and LH concentrations in the rat after the administration of drugs that exert a specificity directed mainly, although not absolutely, toward the mu-, delta-, or kappa-opiate receptors, in order to investigate the role of different receptors and thus the respective endogenous ligands in the modulation of the release of these anterior pituitary hormones. LH concentrations were evaluated in prepuberal female rats, in adult male rats, and in ovariectomized, estradiol benzoate-treated rats. PRL concentrations were evaluated in suckling rats, in ovariectomized, estradiol benzoate-treated rats, and in ether-stressed rats. The delta-antagonist ICI 154129 never affected PRL or LH concentrations, whereas both the mu- and kappa-antagonists, naloxone and MR 1452, respectively, seemed to be effective. However, when graded doses of the two classes of antagonists were tested, the mu-antagonist appeared to be effective on both hormones at doses that were one tenth of those of the kappa-antagonist. In conclusion, the mu-receptor seems to be the most profoundly involved in the regulation of PRL and LH secretion
Interaction between the thyrotropin-releasing hormone-induced growth hormone rise and dopaminergic drugs: studies in pathologic conditions of the animal and man
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Cognitive function in young and adult IL (Interleukin)-6 deficient mice
No full textInterleukin-6 (IL-6) is a cytokine shown to affect brain function and to be involved in pathological neurodegenerative disorders such as Alzheimer's disease (AD). In the present study we investigated the cognitive function in transgenic mice not expressing IL-6 (IL-6 KO) and in wild type (WT) genotype at 4 and 12 months of age, using a passive avoidance and an eight-arm radial maze tasks. Motor function was quantified using an Animex apparatus. Hippocampal choline acetyltransferase (ChAT) activity was evaluated in both genotypes. No difference was observed in both genotypes for spontaneous motor activity. The mean latency (s) to re-enter the shock box, was similar in both young mutant and WT mice. However, a decreased sensitivity (50%) to scopolamine (1 mg/kg) in mutant compared to WT mice, was obtained. IL-6 KO mice exhibited a facilitation of radial maze learning over 30 days, in terms of a lower number of working memory errors and a higher percentage of animals reaching the criterion as compared with WT genotype tested at both ages. Furthermore, mutant mice, at the age of 12 months, showed a faster acquisition (22 days versus 30 days to reach the criterion). The pattern of arm entry exhibited by IL-6 KO mice showed a robust tendency to enter an adjacent arm at both ages, while WT only at the age of 4 months. ChAT activity was inversely correlated with memory performance. These findings suggest a possible involvement of IL-6 on memory processes, even if the mechanism remains still unclear
Effects of beta-endorphinfragment 6-31 on morphine and beta-endorphin-induced growth hormone and prolactin release
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