Neuroimmunomodulatory effects of morphine in Leishmania donovani-infected hamsters.
Neuroimmunomodulation
; 10(5): 261-9, 2002.
Article
em En
| MEDLINE
| ID: mdl-12759563
ABSTRACT
OBJECTIVE:
The effect of morphine on host defense during Leishmania donovani infection in golden hamsters was studied.METHODS:
Hamsters were intracardially infected with L. donovani amastigotes and then monitored by spleen touch print microscopic examination. Morphine and naloxone were administered subcutaneously and intraperitoneally, respectively. Leukocytes were counted by a hemocytometer, and ex vivo phagocytosis was determined by the examination of stained adherent macrophages.RESULTS:
Low doses of morphine, 1.75 and 2.5 mg/kg x 2, administered subcutaneously on day 0 and day 15 significantly (p < 0.05) suppressed the infection, whereas high doses (20.0 and 50.0 mg/kg x 2) exacerbated the infection. On day 30, hamsters treated with low doses of morphine showed a significant (p < 0.05) increase in the number of circulating leukocytes and the pool size and phagocytic activity of peritoneal macrophages ex vivo; in hamsters treated with high doses, all these parameters appeared to be diminished. The bone marrow of morphine-treated hamsters showed a fall in total cellularity and no change in the number of monocytes; however, in those treated with low doses, the infection was completely eliminated by day 30, and paradoxically, a significant (p < 0.05) potentiation of infection was observed in hamsters treated with high doses. The spleens of hamsters treated with both low and high doses of morphine showed a significant (p < 0.05) decrease and increase in weight, respectively; treatment with low doses also caused an almost 2-fold increase in the percentage of monocytes. Morphine apparently exerted its protective effects via naloxone-sensitive opioid receptors; naloxone pretreatment did not affect the potentiation of infection.CONCLUSION:
Conditional doses of morphine apparently biphasically modulated the course of L. donovani infection in hamsters, at least in part through macrophage-mediated mechanisms.
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Base de dados:
MEDLINE
Assunto principal:
Leishmania donovani
/
Adjuvantes Imunológicos
/
Imunossupressores
/
Leishmaniose Visceral
/
Morfina
Limite:
Animals
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article