Neuroimmunomodulation
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Neuroimmunomodulation · Jan 2000
Local application of capsaicin into the draining lymph nodes attenuates expression of adjuvant-induced arthritis.
Adjuvant-induced experimental arthritis (AA) was examined in adult male Lewis rats after isolated capsaicin (CAPS)-induced loss of small, nonmyelinated, afferent fibers in lymph nodes draining the site of adjuvant challenge. AA was induced by intradermal injection of Freund's complete adjuvant (CFA) into the subplantar area of the right hind paw. Controls received similar injections of mineral oil, the vehicle for CFA. ⋯ On days 14 and 20 after challenge with CFA, the inflammatory response in the left hind limb, contralateral to the site of CFA injection, was significantly (p < 0.05) attenuated compared with the response seen on the right side of CFA/CAPS-treated rats, and with the response seen in left hind limb of CFA/vehicle-treated animals. In fact, the mean dorsoplantar width of contralateral hind limbs from CFA/CAPS-treated animals was not different from that measured in non-AA control groups. These findings support a role for small, nonmyelinated, sensory nerves that modulate immune responses in DLN in the development and progression of AA in Lewis rats.
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Neuroimmunomodulation · Jan 2000
Inhibitory effects of endotoxin on LH secretion in the ovariectomized monkey are prevented by naloxone but not by an interleukin-1 receptor antagonist.
Endotoxin (lipopolysaccharides, LPS), the pathogenic moiety of gram-negative bacteria, is a well-known trigger for the central release of cytokines. The objective of this study is to evaluate the effects of systemic endotoxin administration on LH and cortisol secretion in a non-human primate model and to investigate whether these endocrine effects are mediated by centrally released interleukin-1 (IL-1) using the receptor antagonist to IL-1 (IL-1ra). An additional objective is to investigate whether endogenous opioid peptides mediate these endocrine effects of LPS, using the opiate antagonist naloxone. ⋯ These data demonstrate that, in the ovariectomized monkey, a systemic inflammatory/immune- like stress challenge acutely inhibits tonic LH secretion while concomitantly stimulating cortisol release. Although endotoxin is known to affect central cytokine release, these endocrine effects do not require a mediatory role of central IL-1 in the primate. In contrast, endogenous opioid pathways appear to be involved in this process.
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Neuroimmunomodulation · Jan 2000
Natural killer cell activity and resistance to tumor metastasis in prepubescent rats: deficient baselines, but invulnerability to stress and beta-adrenergic stimulation.
Although young children and animals exhibit high rates of tumor development, little is known about natural killer (NK) cell activity in the very young. We recently provided direct evidence that reduced levels of NK activity in prepubescent rats underlie higher levels of susceptibility to metastasis. The aim of the current study was to further characterize NK activity and tumor resistance in prepubescent rats, specifically with respect to the effects of stress and sex, as these factors have been shown to modulate tumor development in adult populations. ⋯ Metaproterenol (0.8 mg/kg, 1 h before testing) resulted in a large suppression of NK activity and resistance against MADB106 metastasis in mature males and females, but not in prepubescent animals. In mature, but not in young animals, males exhibited higher baseline levels of NK activity. Taken together, these findings indicate that NK cells of prepubescent rats are resistant to beta-adrenergic stimulation, and suggest that prepubescent rats are markedly less responsive to SNS-induced suppression of NK activity, which may underlie their invulnerability to the effects of surgery on MADB106 metastasis.