Effect of tissue and plasma factors on kidney proliferation

Liver extract, plasma from intact mice, ES2 tumour extract and plasma from tumour bearing mice has an inhibiting effect on the mitotic activity of hepatocytes and duodenal enterocytes. In the present experiments, the effect of these treatments on the mitotic activity of renal tubular cells was studied. C3HS 28 day-old male mice, standardized for periodicity analysis were used. The determination of normal mitotic circadian curve of the renocytes was done. A second batch of mice were injected with 0.01 ml/gr of either liver extract, plasma from intact mice, ES2 tumour extract or plasma from tumour bearing mice, at 16:00 hours and controlled at 08:00, 12:00 and 16:00 hs during 2 consecutive days post treatment. Colchicine (2 micrograms/gr) was injected 4 hours before killing. Kidneys were processed for histology and mitotic index determinations. Results were expressed as colchicine metaphases per 1000 nuclei, and showed that mitotic activity values of treated animals were significantly lower than those of controls. In conclusion, mitotic activity inhibition of renocytes may be due to some non specific plasmatic and/or tissue factors.

Accion del extracto de higado de ratones parcialmente hepatectomizados sobre la actividad mitotica de los enterocitos del raton joven / Action of liver extract from partially hepatectomized mice on the mitotic activity of young mouse enterocytes

En un trabajo anterior demonstramos que el plasma de retones adultos obtenido 36 horas post hepatectomía parcial, ejerce un efecto inhibitorio en la actividad mitótica de los enterocitos crípticos duodenales del ratón joven. En el presente trabajo se analiza la posibilidad de que dicho efecto se origine en algún factor del hígado regenerante. Para ello se estudia la acción del extracto de hígado de ratones adultos (90 días) obtenido 36 horas después de su hepatectomía parcial (70 por ciento), sobre la actividad mitótica de los enterocitos de ratones jóvenes, analizando 3 niveles celulares de las criptas duodenales. Se emplearon 36 ratones hembra de la cepa C3H/S de 27 días de edad la mitad de los cuales recibió, a las 16:00 horas, una inyección intraperitoneal de solución fisiológica, y restantes extracto hepático (0,01 ml/g). Lotes de 8 animales de cada grupo se sacrificaron a las 08:00/16, 12:00/20 y 16:00/24 (hora del día/horas post tratamiento) previa inyección de colchicina (2mug/g) 4 horas antes. Los resultados, expresados como metafases colchicínas por mil núcleos, demuenstran que la actividad mitótica, en los animales tratados con extracto, es significativamente menor con respecto a los testigos. El efecto inhibidor se manifesta en los niveles celulares de 1 a 4 y de 5 a 12 células de las criptas analizadas. En el nivel superior, de 13 a 20 células, no se aprecia ninguna modificación de la actividad proliferativa. Esta inhibición de la actividad mitótica de los enterocitos de las zonas basal y media de las criptas duodenales es probablemente debido a factores hepáticos difusibles.

Modulation of lymphocyte proliferation by murine liver extract.

Murine liver extract (LEx) purified by ammonium sulfate (45-70% saturation) possesses a strong inhibitory effect on human lymphocyte proliferation. We have shown that the inhibitory effect of LEx is not via a cytotoxic effect and that it is proportional to the length of incubation with LEx. Mitogen-prestimulated lymphocytes are more resistant to LEx inhibition than cells not prestimulated. B cells stimulated by PWM are more susceptible to LEx-induced inhibition than PHA- or Con A-stimulated T cells. In Con A cultures, there may be a population of cells more resistant to LEx inhibition. This population is not yet identified. The degree of reversibility of LEx inhibition was different in cells prestimulated by different mitogens. The inhibitory activity of LEx decreased in the presence of an increasing number of cells in the culture.