EFFECT OF DECABORANE ON HISTAMINE FORMATION IN MICE

¹ Research Center, Rockland State Hospital, Orangeburg, New York

Decaborane (B₁₀H₁₄) has been reported to inhibit stomach histidine decarboxylase in rats, to reduce brain histamine in several species and to reduce histamine levels in stomach and urine of rats (Medina et al. J. Pharmacol. Exp. Ther. 169: 132-137, 1969). We have extended these studies with mice. One day after injection of decaborane mice were either sacrificed and histidine decarboxylase of stomach and brain was tested, or injected with ¹⁴C-l-histidine and ¹⁴C-histamine was measured at intervals suitable for each tissue. We found 1) strong inhibition of histidine decarboxylase from stomach and brain, 2) a marked reduction of in vivo histamine formation in skin and a moderate reduction in brain and 3) enhanced histamine formation in stomach. We agree with Medina et al. that decaborane is the first substance shown capable of in vivo inhibition of brain histamine formation; however, we feel that the reduced histamine levels they observed in stomach and urine might be due to factors other than inhibition of histidine decarboxylase. Other aspects of a decaborane-histamine interaction are discussed.