Monotherapy with histamine dihydrochloride suppresses in vivo growth of a rat sarcoma in liver and subcutis.

The effect of parenterally-administered histamine dihydrochloride (histamine), the role of the histamine H2-receptor and the importance of histamine administration routes on the in vivo growth of a rat Leydig cell sarcoma (LTW) were explored.

METHODS

Wistar/Furth rats with LTW tumours transplanted into subcutaneous and liver tissue received treatment by daily subcutaneous injections or by an osmotic pump for 10 days.

RESULTS

Subcutaneous injections of histamine (0.5 mg/kg) reduced the liver tumour weight by 46+/-8% (p=0.0002) and subcutaneous tumour weight by 41+/-12% (p=0.026) versus animals receiving subcutaneous saline injections. Histamine continuously administered by osmotic pumps at doses of 0.5, 2 and 20 mg/kg/24 hour, did not reduce tumour growth. Ranitidine (50 mg/kg s.c.), inhibited the anti-tumour effect observed by subcutaneous histamine injections. In conclusion, H2-receptor-mediated tumour growth inhibition was accomplished by bolus injections of histamine.