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Biomedical subjects

G B Stefano

Publications and source records attributed to G B Stefano.

At least 19 recordsLinked to original sources
PubMed1995

Occurrence of the opiate alkaloid-selective mu3 receptor in mammalian microglia, astrocytes and Kupffer cells.

Evidence is presented for occurrence of opiate alkaloid-selective, opioid-peptide-insensitive receptor binding sites, labeled with [3H]morphine, in primary cultures of cat microglia and cat astrocytes, as well as on highly purified preparations of rat Kupffer cells. These receptors have been designated mu3 on the basis of their close similarity to receptors first found to be present on human peripheral blood monocytes. Exposure of the microglia to morphine and etorphine caused marked quantifiable changes in cellular morphology, including assumption of a more rounded shape and retraction of cytoplasmic processes; in contrast, several opioid peptides were without effect on morphology. The effects of morphine on microglial morphology were blocked by the opiate antagonist naloxone. These effects of drugs on morphology were as predicted for action via the mu3 receptor. Opiate alkaloid binding sites previously detected on the rat C6 glioma cell line were also characterized here as of the mu3 receptor subtype. It is proposed that mu3 receptors have broad distribution in different macrophage cell types of bone marrow lineage, including microglia and Kupffer cells. Furthermore, these receptors are not restricted to cells of bone marrow lineage, since they are also present on astrocytes.

Alkaloids↗
PubMed1995

Antagonizing effect of morphine on the mobility and phagocytic activity of invertebrate immunocytes.

In the present study we have demonstrated that lipopolysaccharide (LPS) acts as an activator in the immunocytes of molluscs Planorbarius corneus, Mytilus edulis, and the insect Leucophaea maderae. This stimulatory effect, demonstrated by cellular conformational changes, is concentration- and time-dependent, and is antagonized by morphine. The inhibitory effect of morphine can be counteracted by naloxone. Morphine inhibitory action on immunocyte activity is also demonstrated by a decrease in the phagocytic activity. These data suggest that the downregulation of morphine is not limited to vertebrates but is also present in invertebrates.

Animals↗
PubMed1995

Murine macrophage cell lines contain mu 3-opiate receptors.

Opiate alkaloid-selective, opioid peptide-insensitive mu 3 receptors are present in three murine macrophage cell lines (J774.2; RAW 264.7; BAC1.2F5). The receptor binds morphine, its active metabolite morphine 6-glucuronide and certain other alkaloids, but not morphine 3-glucuronide or any of the opioid peptides tested. The cell lines thus provide valuable model systems for investigation of mu 3-opiate receptors, previously demonstrated to mediate inhibitory effects of morphine on activation of human peripheral blood macrophages (monocytes).

Animals↗
PubMed1995

Human granulocytes contain an opiate alkaloid-selective receptor mediating inhibition of cytokine-induced activation and chemotaxis.

Human peripheral blood granulocytes previously were found to contain opioid delta 2-receptors mediating stimulation by opioid peptides of chemotaxis. Studies presented in this work indicate that granulocytes also contain opiate alkaloid-selective, opioid peptide-insensitive receptors mediating inhibition by morphine and other opiates of cytokine-induced activation and chemotaxis. Binding studies with [3H]morphine and [3H]diprenorphine ([3H]DPN) indicated the presence of receptor sites, at considerable density with affinities and selectivity for opiates comparable with those of the mu 3-receptor of human peripheral blood monocytes (macrophages). The influence of the guanosine 5'-triphosphate (GTP) analogue GppNHp on binding indicated that the granulocyte receptor was linked to a G protein. Morphine but not opioid peptides interfered with activation and/or chemotaxis of the granulocytes induced by TNF-alpha, IL-1 alpha, IL-8, and FMLP (chemotactic peptide). These effects of morphine were blocked by the antagonist naloxone. Levorphanol inhibited TNF-alpha-induced activation, and also potentiated the inhibition by morphine. Furthermore, in binding assays, levorphanol enhanced the affinity of the receptor for morphine. Dextrorphan had no effect on activation or chemotaxis, and it also had no effect on binding, indicative of stereoselectivity for the effect of levorphanol. It is concluded that human granulocytes contain opiate alkaloid-selective mu 3-receptors that mediate inhibitory effects of morphine on cellular activation by cytokines.

Adult↗
PubMed1995

Schistosoma mansoni: the presence and potential use of opiate-like substances.

The present study demonstrates that morphine- and codeine-like molecules are present in Schistosoma mansoni following HPLC separation and identification with an appropriate commercially available antibody. Furthermore, the endogenous material, corresponding to morphine, mimics authentic morphine in its ability to induce immunocyte rounding and immobility, an action that is naloxone sensitive. The codeine-like material is not found at high concentrations compared to the morphine-like material, indicating, as in mammals and Mytilus edulis, the potential rapid conversion of codeine to morphine. Coincubation with human leukocytes increases the endogenous level of this material in adult worms, indicating the presence of a positive feedback loop. Last, EDTA, a chelator of divalent cations, has a strong stimulating effect in the synthesis of morphine-like material by the worm as noted by higher levels of this material in its presence. Taken together, the results suggest that this parasite may utilize this immune downregulating molecule in its effort to escape host immunosurveillance as well as in inhibiting an immune response directed against itself.

Analgesics, Opioid↗
PubMed1995

The biology of deception: emotion and morphine.

The biology of deception suggests that denial-like processes are at the core of the cognitive coping. In this regard, with cognitive ability, one associates or assumes that this process occurs by way of a 'rational' mind. Such a detailed cognitive process as being rational would also lead, counter intuitively, to inactivity and or major delays in conclusion reaching. Thus, our perceived rationality may also be a deceptive behavioral response. Of equal noteworthyness, man is also 'emotional'. We surmise that emotion represents the pre-cognitive short-cut to overcome this potential for excessive rationality. In this light, we may explain certain psychiatric disorders such as obsessive-compulsive behavior as emotional extremes dealing with cognitive habits used to bind anxiety operating most probably at the pre-cognitive level. Given recent discoveries in neuroimmunology and an understanding of naturally occurring morphine as both an immune and neurological down-regulatory substance we hypothesize that abnormalities associated with emotional extremes may be due, in part, to morphinergic imbalances.

Adaptation, Psychological↗
PubMed1995

Hyperstimulation of leukocytes by plasma from cardiopulmonary by-pass patients is diminished by morphine and IL-10 pretreatment.

OBJECTIVE: The trauma of cardiopulmonary by-pass (CPB) in cardiac surgery results in a whole body diffuse inflammatory response characterized in part by hyperstimulation of leukocytes. Partially this is due to an increase in the release of biological response modifiers such as cytokines, as noted by the immunocyte stimulatory actions of cell-free plasma obtained postoperatively from CPB patients. The present study was conducted to determine whether CPB plasma induced immunocyte hyperstimulation can be prevented with naturally occurring immune inhibitory substances, specifically, interleukin (IL)-10 and/or morphine. EXPERIMENTAL DESIGN: Controlled in vitro study of the application of drugs to naive immunocytes to block the exitation caused by CPB-plasma. SETTING: University-based tertiary care hospital. PATIENTS: Plasma was obtained from ten patients undergoing CPB. Eligibility included admission for elective cardiac surgery, which no chronic illnesses or acute processes. INTERVENTIONS: Monocytes and granulocytes were pretreated with IL-10 and/or morphine before exposure to plasma obtained from patients undergoing CPB, as CPB-plasma would stimulate naive monocytes and granulocytes in a manner similar to that previously reported in CPB-patients. MEASURES: Computer-assisted microscopic image analysis, measuring cellular conformational and velocity changes, was used to evaluate the effect of treatment on the immunocytes response to stimulation with CPB-plasma. RESULTS: Pretreatment of cells with IL-10 and/or morphine significantly diminished the hyperstimulation induced by CPB-plasma in a concentration-dependent manner. In contrast, when the cells were initially or simultaneously exposed to CPB-plasma, IL-10 and/or morphine had no effect.

Anesthesia↗
PubMed1994

Microglia in invertebrate ganglia.

The results of this study lend strong support to the concept of the existence in insects and molluscs of a distinctive class of neuroglial cells comparable to vertebrate microglia. The evidence presented is as valid as that used in reference to the separate status of vertebrate microglia--i.e., the demonstration of a close structural and functional relationship of these cells with cells of the immune system. As in vertebrates, the excision of ganglia from three invertebrate species (the molluscs Planorbarius corneus and Mytilus edulis and the insect Leucophaea maderae) and their maintenance in incubation media led to an exodus of small cells and their accumulation in the culture dish. During this process, they underwent conformational changes from stellate to rounded, and then to more or less ameboid, comparable to those indicative of the process of activation in the animals' immunocytes. Functional characteristics which these translocated microglia-like cells share with immunocytes are motility, phagocytotic activity, and adherence to the culture dish. Furthermore, the two cells have certain biochemical features in common--e.g., the presence of certain cytokines and (at least in Planorbarius) that of corticotropin. An additional phenomenon of particular interest for the classification of microglial elements is their response to morphine. At 10(-6) M, this drug decreases not only the number of cells emerging from the excised ganglia but also the degree of their transformation to the "active" ameboid form. This dose-dependent and naloxone-sensitive effect of morphine on microglial cells parallels that on activated immunocytes of the same species. Corresponding results demonstrating an inhibitory effect of morphine on mobilized microglial cells of the frog Rana pipiens indicate that this relationship between the two cell types under consideration also exists in vertebrates. Binding and displacement experiments with membrane homogenates of microglial cells as well as immunocytes of Mytilus have shown that the effects of morphine on both cell types are mediated by the same special opiate receptor (mu 3).

Animals↗
PubMed1994

Inhibition of the calcitonin-induced outward current in identified Aplysia neurons by interleukin-1 and interleukin-2.

1. The effects of bath-applied recombinant human interleukin-1 (rhIL-1) and interleukin-2 (rhIL-2) on the calcitonin (CT)-induced outward current recorded from identified neurons (R9-R12) of Aplysia kurodai were investigated with conventional voltage-clamp and pressure ejection techniques. 2. Micropressure ejection of CT onto the soma of the neuron induced a slow outward current [Io(CT); 4-6 nA in amplitude, 30-40 sec in duration] associated with a decrease in input membrane conductance. 3. Io(CT) was increased by hyperpolarization. 4. The extrapolated reversal potential was +10 mV. Additionally, Io(CT) was sensitive to changes in (Na+)o but not to changes in (K+)o, (Ca2+)o, and (Cl-)o. 5. Micropressure-ejected forskolin produced a slow outward current similar to that induced by CT. 6. Bath-applied rhIL-1 and rhIL-2 (10-40 U/ml) reduced the CT-induced current in identified Aplysia neurons without affecting the resting membrane conductance or the holding current. 7. The inhibitory effects of both cytokines on the current were completely reversible. Heat-inactivated rhIL-1 and rhIL-2 were without effect. 8. These results suggest that the immunomodulators, IL-1 and IL-2, can modulate the CT-induced outward current associated with a decrease in Na+ conductance in the nervous system of Aplysia. Therefore, the study suggests that these cytokines may also serve as neuromodulators.

Animals↗
PubMed1994

Inhibitory effect of morphine on granulocyte stimulation by tumor necrosis factor and substance P.

We demonstrate that morphine, at higher concentrations than that effective in the inhibition of spontaneously active cells, can antagonize stimulation of human granulocytes by tumor necrosis factor (TNF) or substance P. The antagonistic effect appears to occur indirectly by way of downregulation of the cells' responsiveness to these stimulatory substances. We have previously shown that neutral endopeptidase 24.11 (NEP) is an important enzyme in neuro- and autoimmunoregulation of both vertebrates and invertebrates, and that activation of human granulocytes by monokines and neuropeptides results in regulation of NEP. Exposure of intact human granulocytes to morphine increases NEP by a naloxone-sensitive mechanism. The increased expression of NEP downregulates the stimulatory effect of substance P and TNF. In the case of substance P, we demonstrate the significance of NEP in modulating the process of downregulation by use of a specific NEP inhibitor, phosphoramidon. These results indicate that morphine is a significant factor in downregulating immunocyte responsiveness to NEP substrates and also to those signal molecules (i.e. cytokines) not metabolized by it. In summary, we infer that opiates may be endogenous signal molecules, a status that appears to be amply supported by their immunosuppressive actions.

Granulocytes↗
PubMed1994

Differential modulation of invertebrate hemocyte motility by CRF, ACTH, and its fragments.

Various reports have shown that invertebrate hemocytes are responsive to mammalian neuropeptides and cytokines. In the present study, we demonstrate that corticotropin-releasing factor (CRF) and adrenocorticotropin (ACTH) fragments (1-24), (1-4), (4-9), (1-13), (1-17), and (11-24) significantly stimulate molluscan hemocyte migration, and the whole sequence (1-39) and the fragment (4-11) have an inhibitory effect. Differences between species were found with respect to the response to individual fragments. Additionally, the (4-11) fragment was able to antagonize some of the stimulatory fragments (4-9) as well as tumor necrosis factor (TNF-alpha)-induced chemotaxis. Our results suggest that invertebrate hemocytes are able to respond to CRF and ACTH fragments that in turn provide further evidence of the complexity of intercellular signaling within the immune system in relatively primitive animals. Thus, auto- and neuroimmunoregulatory activities in mammals must have had an earlier beginning than previously believed.

Adrenocorticotropic Hormone↗
PubMed1994

The stress response and autoimmunoregulation.

Using the recent burgeoning of information on how the stress response systems interact, and combining this with advances in our understanding of neuroimmune communication, a proposed neuroendocrine-neuroimmune stress response system incorporating autoimmunoregulation is reviewed. The study of immunocyte behavior in certain clinical conditions associated with a variant stress response may help illuminate the functioning of the neuroendocrine-neuroimmune stress response system.

Animals↗
PubMed1993

Evidence for nitric oxide production and utilization as a bacteriocidal agent by invertebrate immunocytes.

The present study demonstrates that molluscan immunocytes are able to produce a chemical bacteriocidal substance which can be indirectly identified as nitric oxide (NO). The cells were analyzed in vitro on slides using computer-assisted microscopic image analysis to detect changes in cell conformation as well as to quantify the number of bacteria present. Sodium nitroprusside yields NO in solution causing bacterial clumping. The same phenomenon occurs in the presence of invertebrate immunocytes. Escherichia coli lipopolysaccharide also increases the number of bacteria found around the immunocytes, but this effect is selectively prevented by the addition of inhibitors of nitric oxide synthase, suggesting that this bacterial clumping is caused by the cells liberating NO. Interestingly the cells presumably producing NO maintain a round morphology. These findings suggest that immunocytes are able to kill bacteria by two mechanisms, i.e., phagocytosis and NO production.

Animals↗
PubMed1993

Opiate-like substances in an invertebrate, an opiate receptor on invertebrate and human immunocytes, and a role in immunosuppression.

The presence of morphine-like and codeine-like substances was demonstrated in the pedal ganglia, hemolymph, and mantle tissues of the mollusc Mytilus edulis. The pharmacological activities of the endogenous morphine-like material resemble those of authentic morphine. Both substances were found to counteract, in a dose-dependent manner, the stimulatory effect of tumor necrosis factor alpha or interleukin 1 alpha on human monocytes and Mytilus immunocytes, when added simultaneously to the incubation medium. The immunosuppressive effect of this opiate material expresses itself in a lowering of chemotactic activity, cellular velocity, and adherence. Codeine mimics the activity of authentic morphine, but only at much higher concentrations. Specific high-affinity receptor sites (mu 3) for morphine have been identified on human monocytes and Mytilus immunocytes. In Mytilus recovering from experimentally induced stress, the return of "altered" immunocytes to a more inactive state appears to be due to a significant rise in the content of morphine-like material in the pedal ganglia and hemolymph at this time. Thus, morphine may have a role in calming or terminating the state of immune alertness.

Animals↗