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Effect of L-alanine and some other amino acids on thymocyte proliferation in vivo
1Department of Histology and Neurobiology, Karolinska Institute, Stockholm, Sweden.
L-alanine was shown earlier to play a significant role for the proliferation of lymphocytes in vitro. In the present work the effect of L-alanine and some other amino acids on thymocyte proliferation was studied in vivo by local administration into one thymus lobe of guinea pigs. Proliferating cells were pulse labelled with bromodeoxyuridine (BrdUrd). The labelling index of the treated lobe significantly exceeded that of the contralateral, control lobe at 48 h after treatment with 10 or 100 micrograms L-alanine, indicating stimulated proliferation. The higher dose, which was also tested after other time intervals, stimulated also at 24 h. The difference in proliferative activity between the lobes was verified by mitotic studies. The effect of L-alanine was mainly on the large, low density, highly proliferating precursor cells. No other amino acids tested (D-alanine, cysteine, hydroxyproline, serine, tryptophan), or pyruvate produced significant differences between the treated and control lobes.
L-alanine was shown earlier to play a significant role for the proliferation of lymphocytes in vitro. In the present work the effect of L-alanine and some other amino acids on thymocyte proliferation was studied in vivo by local administration into one thymus lobe of guinea pigs. Proliferating cells were pulse labelled with bromodeoxyuridine (BrdUrd). The labelling index of the treated lobe significantly exceeded that of the contralateral, control lobe at 48 h after treatment with 10 or 100 micrograms L-alanine, indicating stimulated proliferation. The higher dose, which was also tested after other time intervals, stimulated also at 24 h. The difference in proliferative activity between the lobes was verified by mitotic studies. The effect of L-alanine was mainly on the large, low density, highly proliferating precursor cells. No other amino acids tested (D-alanine, cysteine, hydroxyproline, serine, tryptophan), or pyruvate produced significant differences between the treated and control lobes.