Hormonal regulation of rapid eosinopenia in the rat

The stress of handling and taking blood samples from adult male Sprague Dawley rats every 10 minutes for 60 minutes resulted in eosinopenia within 10 minutes. The fall in eosinophils reached a nadir of 63% of the nonstressed sample by 40 minutes. This eosinopenia was mediated by way of the adrenocortical steroids as indicated by the failure of both adrenalectomized and hypophysectomized rats to react to the stress of handling and sampling with an eosinopenic response similar to the intact controls. The response was not dependent on the stimulation of beta-adrenergic receptors by epinephrine since propranolol, a beta-adrenergic blocking agent, failed to produce any diminution of the eosinopenic response.