Interaction between Thyrotropin-Releasing Hormone and Prolactin-Producing Cells

Abstract

In 1968 Tashjian and co-workers reported the establishment of three strains of epithelial cells from a transplantable rat pituitary tumor (MtT/ W5) originally induced in a Wistar-Furth rat by radiation (Takemoto et al., 1962). The different cell strains are referred to collectively as GH cells, and the specific strains have appropriate designations. In culture, GH cells spontaneously synthesize and secrete into the culture medium large quantities of prolactin (PRL) and/or growth hormone (GH). The hormones are immunologically indistinguishable from authentic rat hormones, and they have retained their biological activity (Tashjian et al., 1968; Tashjian and Hoyt, 1972; Haug and Gautvik, 1976, 1978). The GH cells are aneuploid. In 1970 the modal chromosome number of the GH3 cell strain was 69 per cell (Sonnenschein et al., 1970). Seven years later a significant reduction in modal chromosome number to 62–64 was found (Clausen et al., 1977), indicating that during these years of continuous culture either a loss or a rearrangement of chromosomes had occurred. The observed reduction in chromosome number is not associated with dramatic changes in cell growth and hormone production (Tashjian and Hoyt, 1972; Clausen et al., 1977).