SYSTEMIC NEUTROPHILIA OBSERVED DURING ANAPHYLACTIC SHOCK IN RATS IS INHIBITED BY DOPAMINERGIC ANTAGONISTS

The involvement of the sympathetic and dopaminergic systems on blood n eutrophilic leucocytosis observed during anaphylaxis was investigated. Blood neutrophil counts impressively increased 1 h after intravenous injection of ovalbumin (OVA, 250 mu g/kg) into OVA-immunized rats. The increase in neutrophil counts induced by OVA was abrogated after cate cholamine depletion by reserpine. Either adrenalectomy or the alpha- a nd beta-adrenoceptor antagonists phentolamine and propranolol, respect ively, had only minor inhibitory effects on neutrophilia induced by an tigen. On the other hand, pretreatment with the dopaminergic antagonis ts chlorpromazine and pimozide significantly inhibited the neutrophili a. The intravenous injection of apomorphine, a dopaminergic agonist, i ncreased neutrophil counts in naive animals, while chlorpromazine comp letely inhibited this phenomenon. These results suggest that dopaminer gic mechanisms play a role in the systemic neutrophilia observed durin g anaphylactic shock.