Studies of hormonal and nutritional influence on intrauterine development led the authors to propose that the growth of the foetal brain is regulated by unique brain trophin. This paper describes studies which indicate the presence of a brain trophin in peripheral serum and demonstrates its dependence upon the pituitary gland. An in vitro system to determine growth promoting factors was developed. The assay is based upon the ability of proliferating cultured foetal brain cells to incorporate tritiated thymidine into DNA. Following incubation of the brain cells, DNA is extracted and the incorporation of tritiated thymidine into each DNA fraction provides an index of brain cell proliferation. Serum is shown to be a necessary requirement for foetal brain cell proliferation. The concentration of serum in the medium demonstrates a highly significant correlation with incorporation of tritiated thymidine (R = 0.9837, t = 60.902, p < 0.001). The assay sensitivity is 1.5 μl of serum or 102 μg of serum protein. Although the assay utilizes rat receptors, the serum response is not species specific, having been repeatedly demonstrated in human, rabbit, rat and bovine serum. The brain growth promoting activity of serum was shown not to be due to any nutrient contribution.
|Number of pages||1|
|Journal||Proceedings of the Endocrine Society of Australia|
|Publication status||Published - 1975|