Early increase in histamine concentration in the islets of Langerhans isolated from rats made diabetic with streptozotocin.

Sprague-Dawley rats were separated in 4 groups. G1 received streptozotocin (ST). G2 received nicotinamide (NC) followed by ST. G3 was a NC control and G4 was a citrate control. The rats were sacrificed after 28 h and the islets isolated. Histamine and histaminase were determined. In the islets there was an increase in histamine content in G1 and a smaller increase in G2. The first two groups differ significantly and also in relation to the control groups. A decrease in islet histaminase does not seem responsible for the increased histamine, since group 2 (NC + ST) which had no diabetes, had a lower activity than group 1 (ST). It is suggested that histamine liberation by ST may be related to the diabetogenic effect of this drug.