ovalbumin and dimethyl-sulfide

To clarify the contribution of stress to classical conditioning-associated asthmatic responses, the effect of fasting stress on conditioned histamine release was investigated in a guinea pig model of asthma. The animals were randomly divided into 2 groups for Experiment 1 and 2, and received a conditioning procedure in which ovalbumin (OA) as an unconditioned stimulus (US) and dimethylsulfide (DMS, sulfur smelling) as a conditioned stimulus (CS) were simultaneously inhaled after fasting for 16 h. Then, one group was given food as a reward for respiratory distress, and the other group was denied it for more than 3 h, while being placed in front of the feeding group. After this procedure was repeated 5 times, the plasma histamine levels in response to the CS were measured in half of each group in Experiment 1, and the respiratory resistance (Rrs) was assessed similarly in the other half of each group in Experiment 2. The same experiments were again performed after exchanging assignments of feeding group or fasting group in both experiments. The control groups in both experiments received the CS and the US 10 times separately in a random order under 16 h fasting conditions and were provided food after the exposures. After these pseudo-conditioning presentations, the plasma histamine levels or the Rrs in response to the CS were measured. In Experiment 1, the plasma histamine levels in the fasting stress group after the first conditioning sessions were significantly higher than those of the other groups. This difference was not observed when the groups were exchanged. In Experiment 2, the fasting stress group showed higher values in the Rrs compared to the other groups, irrespective of the first or second conditionings; however, they were not significant. The present study indicates that fasting stress after the conditioning procedures exacerbates the following conditioned histamine release, although the stress effect on bronchoconstriction was not confirmed.

Topics: Animals; Asthma; Bronchoconstriction; Conditioning, Classical; Disease Models, Animal; Food Deprivation; Guinea Pigs; Histamine; Histamine Release; Inhalation Exposure; Male; Ovalbumin; Passive Cutaneous Anaphylaxis; Stress, Psychological; Sulfides

An attempt of classical conditioning of anaphylaxis by odor was carried out, using actively sensitized guinea pigs with an inhalation of ovalbumin (OA). One month after sensitization, animals were divided into the conditioned group; group C, and the unconditioned group; group U, consisted of 6 animals, respectively. Dimethylsulfied (DMS: sulfur odor), was inhaled in group C as a conditioned stimulus with OA which is an unconditioned stimulus, while only OA was inhaled in group U. Four days after these procedures, saline was inhaled in group C and DMS was solely inhaled in group U in order to equalize the total inhaled dose of OA and DMS in both groups. These sessions were repeated once a week for seven weeks. After final sessions, all animals were inhaled DMS, saline and OA separately, and blood samples were drawn after each inhalation to measure plasma histamine levels. After an inhalation of DMS only, plasma histamine levels of group C and U were 47.5 +/- 9.7 and 25.7 +/- 1.2 ng/ml, respectively. In group C, plasma histamine levels were 32.9 +/- 4.7 at the inhalation of saline and 59.0 +/- 9.2 ng/ml at OA inhalation. Plasma histamine level after an inhalation of DMS only was significantly higher in group C than that in group U (p < 0.05). These results suggest that the conditional stimulus (DMS inhalation) may induce histamine release in the absence of any antigenic stimulus and support the evidence for mast cell-neuron interaction.

Topics: Anaphylaxis; Animals; Conditioning, Classical; Guinea Pigs; Histamine Release; Immunization; Male; Odorants; Ovalbumin; Sulfides