A Suggested Effect on Levels of Catecholamine in Brain produced by Small Doses of Reserpine

Abstract

IN a recent communication, Sheppard and Zimmerman¹ criticized the results obtained by numerous other workers indicating that reserpine reduces the content of brain norepinephrine and serotonin. Their objections were based on the “toxicological doses” which had been used. However, they failed to mention that reserpine had also been reported to reduce levels of brain serotonin² and norepinephrine³ in non-toxic doses as low as 0.1 mgm./kgm. and to deplete heart norepinephrine in doses as low as 5 µgm./kgm.⁴. Sheppard and Zimmerman's results showed that the administration of 0.1 mgm./kgm. of reserpine subcutaneously to female guinea pigs weighing 300 gm. elicited a rise of 74 per cent in brain norepinephrine in 20 min. and a rise in heart norepinephrine of 30 per cent in 20 min. and 45 per cent in 2 hr. No diminution in brain and heart norepinephrine was noted for 8 hr. In contrast, serotonin-levels in the brain fell by 50 per cent in 4 hr. They concluded that their results constituted the first demonstration of a rise in catecholamine content following the administration of reserpine.