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An important function of the sympathetic nervous system is to maintain homeostasis by modulating the level of cellular activity in many diverse organ systems. The sympathetic neurotransmitter norepinephrine modulates the level of T and B lymphocyte activity by binding to the beta2-adrenergic receptor (beta2AR). The present study was designed to elucidate(More)
Morphine has been reported to possess immunosuppressive actions in both in vitro as well as in vivo assays of immune function. Our work in female B6C3F1 mice, surgically implanted with a 75-mg time release morphine pellet, has confirmed previous reports of a rapid loss in the cellularity of the spleen and thymus. To evaluate the effect of morphine on the(More)
We tested the hypothesis that the previously observed loss of thymic lymphocytes in mice after treatment with time-release morphine pellets was occurring through the process of apoptosis. Apoptosis is a form of cell death, distinct from necrosis, which involves a specific endonuclease that fragments the cell's own DNA. Forty-eight hours after implantation(More)
2,4-Diaminotoluene (DAT) has been demonstrated to be a potent carcinogen. The present studies were carried out to determine the toxic and immunotoxic potential of DAT. Mice exposed to DAT at 25-100 mg/kg per day for 14 days by gavage showed a 42% increase in liver weight and a slight decrease in spleen weight. Histopathologic evaluation of selected organs(More)
A number of 2'3'-dideoxynucleosides have been reported to markedly inhibit the in vitro growth of HIV, the causative agent of acquired immunodeficiency syndrome (AIDS). Clinical trials have shown that the continued therapeutic use of these nucleoside derivatives can be associated with adverse side effects. Since these side effects include myelotoxicity, as(More)
Morphine is a drug of abuse with an ability to down-regulate immune responsiveness that could have potentially serious consequences in both heroin addicts and in the clinical environment. The exact mechanism of action by which morphine induces immunosuppression has yet to be clearly determined. A direct mechanism of action is suggested to operate through(More)
Recent evidence has implicated enkephalins as immunomodulators. Several studies have reported the regulation of tumor growth by methionine enkephalin (ME). However, there has been little effort to relate the immunological significance of enkephalins to the development of anticancer drugs. The present study had three aims: first, to compare the antitumor(More)
Morphine suppresses humoral immune responses, causes thymic hypoplasia and suppresses NK (natural killer) activity in animal models. There is evidence that thymic hypoplasia and NK suppression are predominantly mediated by indirect mechanisms. The mechanism of morphine-induced humoral immunosuppression is less certain. Recent reports suggest that morphine(More)
Morphine sulfate has previously been shown to produce a dose-dependent decrease in hepatic phagocytosis when administered as 8-, 25- and 75-mg pellets implanted subcutaneously. This study was undertaken to determine the time course of suppression of hepatic and splenic phagocytosis after subcutaneous implantation of morphine sulfate pellets. Mice were(More)
Numerous reports in the literature describe the effects of beta-adrenergic agonists and/or their second messenger cyclic AMP on in vitro and in vivo immune responses. The fact that the murine spleen receives rich adrenergic innervation and that the pharmacologic disruption of this innervation leads to altered immune responsiveness has led some investigators(More)