Biomedical subjects

S Demissie

Publications and source records attributed to S Demissie.

41 records · Page 3Linked to original sources

PubMed1993

Conditioning of the allogeneic cytotoxic lymphocyte response.

Allogeneic cytotoxic T-lymphocyte (CTL) response can be obtained following immunization of BALB/c mice with C57BL/6 spleen cells. We investigated the possibility of behaviorally conditioning this response by associating the C57BL/6 spleen cell immunization [unconditioned stimulus (US)] with camphor odor [conditioned stimulus (CS)]. We reported the possible mechanisms involved in the conditioning of natural killer cell activity. Similar approaches were used to investigate the mechanisms that participate in the conditioned CTL activity. The first mechanism of investigation utilized opioid receptor blockers naltrexone and quaternary naltrexone. Naltrexone, which blocks both the central and peripheral opioid receptors, blocked the recall of the conditioned response, whereas quaternary naltrexone, which does not penetrate the blood-brain barrier, was unable to block the conditioned response, demonstrating that centrally located opioid receptors play a role in the recall of the conditioned response. The studies are of interest because they indicate that resistance or susceptibility to various diseases such as cancer, autoimmunity, and infectious diseases might be influenced by the regulatory network of the CNS.

Animals↗

PubMedDate not supplied

Lidocaine interrupts the conditioned natural killer cell response by interfering with the conditioned stimulus.

In the present study, lidocaine, a local anesthetic that inhibits the initiation or conduction of nerve impulses, was used to differentiate between the memory for the conditioned stimulus (CS) and the memory for the CS and unconditioned stimulus (US) association. Lidocaine was used to block memory formation. It was administered into the cisterna magna to localize the inhibition to the central nervous system (CNS) where circuits for the CS and US exist. The results show that lidocaine specifically blocks the ability of the CS to stimulate the circuits responsible for storing the CS/US association, but it does not interfere with the inherent ability of the US to signal the CNS and trigger a peripheral response. The observation that the CS circuit can be interrupted independently of the US circuit suggests that these signals come together to form a new circuit for the memory of the association. The association memory forms later and is independent of the memory for the CS.

Animals↗

PubMedDate not supplied

Conditioning of body temperature and natural killer cell activity with arecoline, a muscarinic cholinergic agonist.

Arecoline, a muscarinic cholinergic agonist, was found to depress body temperature and elevate the activity of preactivated natural killer (NK) cells. To demonstrate that the unconditioned responses produced by arecoline were mediated through central nervous system pathways, we used the drug as an unconditioned stimulus. By pairing camphor odor (conditioned stimulus) with arecoline (unconditioned stimulus), it was possible to simultaneously condition both a decrease in body temperature and augmentation of NK cell activity. The observations suggest that although both the modulation of body temperature and NK cell activities are integrated at the level of the hypothalamus, these pathways of regulation can be differentiated.

Animals↗

PubMedDate not supplied

Afferent signals to the CNS appear not to condition the modulation of interleukin-1 receptors in the hippocampus.

Conditioned alteration of natural killer (NK) cell activity was used as an indicator of the functional bidirectional communication between the immune and central nervous systems. Poly I:C and lipopolysaccharide (LPS) from Escherichia coli and Salmonella typhimurium were used as unconditioned stimuli and odor of camphor as the conditioned stimulus. An attempt was made to demonstrate the role of central interleukin (IL-1) receptors in this communication process. Brain IL-1 receptors were down-regulated by treatment with 50 microg/mouse of LPS from S. typhimurium, but not with the same dose of LPS from E. coli or poly I:C. A significant level of conditioned augmentation of NK cell activity was observed with poly I:C. Conditioned alteration in NK cell activity was also observed with LPS from E. coli, but at much lower level than poly I:C. NK cell activity was not conditioned with LPS from S. typhimurium at the same dose as E. coli LPS, but conditioned enhancement of NK cell activity was observed with a higher dose (100 microg) of S. typhimurium LPS. These results suggest that modulation of central IL-1 receptors do not seem to play a role in the conditioned augmentation of NK cell activity.

Afferent Pathways↗

PubMedDate not supplied

NK cell and CTL activities can be raised via conditioning of the CNS with unrelated unconditioned stimuli.

Poly I:C, an inducer of interferon alpha and beta, and arecoline, a cholinergic muscarinic agonist, were used as unconditioned stimuli in conjunction with camphor odor to condition the augmentation of natural killer (NK) cell and cytotoxic T lymphocyte (CTL) activities. This observation suggested that two unrelated unconditioned stimuli might be used to associate the signals, and induce mediators at recall that can raise natural killer cell activity. In animals stimulated with an alloantigen to induce CTL, we observed that either poly I:C or arecoline conditioned association, and recall with the same CS raised CTL activity. It appears that conditioning with different substrates can raise either native (NK cell activity) or acquired (CTL activity) immunity. The studies suggest that communication between the CNS and NK cells or CTL appear to take place through a common pathway(s).

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