EFFECTS OF RESERPINE ON MAO AND ON SEROTONIN-AND NORADRENALINE-CONTENTS IN RAT STOMACH

Abstract

Effects of reserpine, iproniazid and 6-hydroxydopamine (6-OH-DA) on monoamine oxidase (MAO) activity and on serotonin-and noradrenaline-contents in rat brain, liver and stomach, both in vitro and in vivo, were investigated and the following results were obtained.
(1) An intraperitoneal injection of reserpine in rat resulted in a significant increase in MAO activity after 24 hours in brain by 120% of the control with serotonin as substrate, but no change in activity with tyramine as substrate. On the other hand, liver MAO activities both with serotonin and tyramine as substrate were not changed by reserpine pretreatment. (2) Reserpine showed a slight inhibition of MAO activity in rat stomach, in vitro, with benzylamine as substrate. (3) Pretreatment with 6-OH-DA did not cause any change in MAO activity in brain but with combination of 6-OH-DA and iproniazid, MAO activity was inhibited strongly. However, MAO activity in stomach was reduced with the all pretreatment mentioned above. (4) With reserpine pretreatment, serotonin in brain disappeared almost completely, but it resulted in a slight incraese of 112% of serotonin content in stomach. With iproniazid pretreatment, serotonin content resulted in 278% and 168% increase in brain, and in stomach, respectively. With combination of reserpine and iproniazid, serotonin content was reduced by 83% in brain, but was increased by 147% in stomach. Similarly, with 6-OH-DA pretreatment, serotonin content was reduced by 88% in brain, but was increased by 156% in stomach. With the combination of 6-OH-DA and iproniazed, serotonin content was increased by 164% in brain and by 135% in stomach. (5) With reserpine pretreatment, noradrenaline content was reduced almost completely both in brain and stomach. With iproniazid pretreatment, noradrenaline content was incre ased by 245% in brain, and by 171% in stomach, but with combination of reserpine and iproniazid, it was reduced almost completely both in brain and stomach. With 6-OH-DA pretreatment, noradrenaline content was reduced remarkably both brain and stomach. Furthermore, with combination of 6-OH-DA and iproniazid noradrenaline content was reduced by 63% in brain, and was reduced almost completely in stomach. (6) Clearly ulcers in rat stomach 24 hours after pretreatment with reserpine or with combination of reserpine and iproniazid were found.