The effect of placenta hydrolysate on the physiological parameters and survival of mice exposed to 6.5 Gy X-ray irradiation

The radioprotective properties of a human placenta hydrolysate known commercially as Laennec (Japan Bio Products, Co. Ltd., Japan) were studied. The preparation was administered intraperitoneally to male ICR (CD-1) mice using two regimens. In the first scenario, the mice received 112 μg/g of the preparation at 30 min and one, two, and three days after irradiation. Alternatively, they were given five daily injections of the preparation at a dosage of 112 μg/g and exposed to 6.5 Gy irradiation on the third day after the final administration. The efficacy of the preparation was assessed by 30-day survival rate, as well as by biological indices obtained four days after irradiation (number of nucleated cells in bone marrow, content of thiobarbituric acid reactive substances (TBARS) in liver, and leukocyte and platelet levels in blood). Neither of the two regimens improved survival or alleviated pancytopenia in the irradiated mice. However, the reduced TBARS contents in liver suggest that the preparation may exert a slight inhibitory effect on the metabolism of lipid radiotoxins.