Effects of beta-adrenergic receptor blockade on stress-induced changes in hematological parameters of rats

This study was carried out to examine the effects of acute and chronic stress on hematological parameters in combination with β-adrenergic receptor blockade in rats. In the present study, acute stress is a form of short-term stress induced by a single footshock session, and chronic stress is a form of long-term stress induced by multiple and repetitive footshock sessions. Male Wistar rats were treated with propranolol (5 mg/kg s.c.) and were subjected to an acute stress [intermittent session of footshock: 0.5 mA, during 60s (5s shock, 5s pause) at one and three days after the moment of propranolol administration] and to a chronic stress [intermittent session of footshock: 0.5 mA, during 60s (5s shock, 5s pause) over three consecutive days from the moment of propranolol administration]. Control group rats were subjected to the same conditions without the propranolol administration and were treated with saline solution. Four days after the drug administration, we assessed the number of total erythrocytes, the erythrocyte indexes (mean cell volume, MCV; mean cell hemoglobin, MCH; mean cell hemoglobin concentration, MCHC) and the number of thrombocytes. The results indicate that hematological parameters differed under acute and chronic stress conditions in combination with adrenergic receptor blockade. β-adrenergic receptor blockade with propranolol enhances the total number of erythrocytes under acute stress influences and the total number of thrombocytes under chronic stress influences. Acute and chronic stress in combinaton with β-adrenergic blockade has no significant effect on erythrocyte indexes. Propranolol administration in low doses during different forms of stress could prevent erythrocyte disorders after stress exposure and symptoms in post-traumatic stress disorders. Propranolol markedly suppressed the tachycardia induced by footshock stress after chronic administration. On the whole, the obtained data indicate the important role of β-adrenoreceptor mechanisms in the regulation of erythrocyte dynamics.