| Abstract: | The effects of oral and intravenous nutrition on host and tumor responses to graded doses of methotrexate (MTX) were evaluated in 150 adult Sprague-Dawley rats. All animals were inoculated with Walker-256 carcinosarcoma and were fed a regular diet for ten days before assigning them to three dietary groups. Group I (n = 64) received a constant intravenous infusion of 30% dextrose-5% amino acids (IVH), group II (n = 64) received an identical solution orally ad libitum, and group III (n = 22) received a regular diet ad libitum. Animals in groups I and II were then divided into three subgroups each that received either 20 mg/kg, 40 mg/kg, or 60 mg/kg of MTX intramuscularly. Ten days later, all surviving animals were killed. Animals fed the 30% dextrose-5% amino acid diet orally and given 20 mg/kg and 40 mg/kg of MTX lost slightly less body weight when compared with their IVH counterparts. In the 60 mg/kg treatment group, orally fed animals lost 52 gm of body weight compared with 23 gm in IVH animals. IVH rats given 20 mg/kg and 40 mg/kg of MTX demonstrated significant inhibition of tumor growth and decreased tumor weight/body weight ratios when compared with orally fed rats. No improvement in tumor response to 60 mg/kg of MTX was observed, however, when IVH animals were compared with orally fed rats. In a second study, nutrient intake was maintained at a constant level by intravenous infusion in one group and intrajejunal infusion in another group of tumor-bearing rats. Host and tumor responses to 20 mg/kg of MTX were similar in both groups of animals. |
