INHIBITION OF TISSUE HISTAMINE FORMATION BY DECABORANE

¹ Pharmacology-Biochemistry Branch, Biosciences Division, United States Air Force School of Aerospace Medicine, Brooks Air Force Base, Texas

The effect of decaborane (B₁₀H₁₄) upon tissue levels of histamine and histidine decarboxylase activity was studied. In rats decaborane reduced the levels of histamine in kidney, liver, stomach and urine but had no effect on heart. Brain histamine was also diminished by 50% in mice, rats, guinea pigs and rabbits. Histamine depletion was still apparent in rat brain one week after a single injection of decaborane (15 mg/kg), whereas depletion of rat stomach histamine lasted only 48 hours. It was suggested that this may be due to a difference in the turnover rate of histamine in the two tissues. Histidine decarboxylase activity (rat glandular stomach) was strongly inhibited after injection of decaborane. Other drugs tested had no effect on rat brain histamine. The data suggest that decaborane may depress histamine levels by inhibiting histidine decarboxylase and that brain histamine may exist in different metabolic pools.