Effect of Diethylstilbestrol-Induced Tumorigenesis on the Secretory Activity of the Rat Anterior Pituitary Gland1

Effects on the Secretion of Pituitary Growth Hormone, Thyroid Stimulating Hormone, Luteinizing Hormone and Follicle Stimulating Hormone in Rats Rendered Hyperprolactinaemic by Chronic Treatment with Oestrogen

“…The results of this investigation confirm and extend the earlier conclusions bf Meyer and Clifton (1956) concerning the chronic effects of diethylstilboestrol on pituitary hormone secretion and demonstrate that while there is gross perturbation of one hormone (prolactin), this is also associated with marked effects on the secretiQ.p. of other pituitary hormones.…”

“…While the hypersecretion of prolactin is a significant endocrine result of oestrogen treatment it might be anticipated that the changes in the status of brain biogenic amines in this situation would also alter the secretion of other pituitary hormones which are thought to be under some degree of central control by these amines. In an early study prior to the availability of radioimmunoassays for pituitary hormones Meyer and Clifton (1956) produced biological data suggesting that the chronic administration of diethylstilboestrol, as well as inducing prolactin-secreting tumours, resulted in reduced pituitary concentrations of growth hormone (GH), thyroid stimulating hormone (TSH), luteinizing hormone (LH) and follicle stimulating hormone (FSH).…”

Characteristics of Prolactin Secretion in Normal and Estrogen-Treated Pituitaries of Rats at the Single Cell Level: Analysis by Reverse Hemolytic Plaque Assay.

“…Our finding that the mean plaque area of pituitary tumor cells was smaller than that of the normal pituitary can be explained as follows: (1) normal pituitaries are under inhibitory control by DA in vivo, but when pituitary cells are transferred into an in vitro environment, they are released from inhibitory DA control and PRL secretion may increase; (2) In normal pituitary cells, the wide variation in the amount of PRL secretion at a single cell level (functional heterogeneity) and the multimodal distribution pattern of the plaque areas did not change significantly after 6 weeks of age. However, Luque et al [22] have demonstrated that a bimodal frequency distribution of plaque areas exists in normal rat pituitaries in the proestrous phase in the RHPA.…”

“…THE CHRONIC administration of estrogen (E2) is known to increase the size of the anterior pituitary gland, the serum prolactin (PRL) concentration and the percentage of PRL-secreting cells, and to induce pituitary tumors [1,2]. Reverse hemolytic plaque assay (RHPA) has enabled us to analyze hormone secretion from individual cells [3,4].…”

Oestrogen-Induced Hyperprolactinaemia in the Rat: Reduced Concentrations of Hypothalamic Dopamine and the Effects of Bromocriptine

“…The mechanism whereby oestrogen administration induces hyperprolactinaemia and prolactin-secreting pituitary adenomas in rodents (Meyer and Clifton 1956;Caligaris and Taleisnik 1974;Lloyd et al 1975) remains to be elucidated. It has been proposed that the effect of oestrogen is a direct one on the pituitary, related to reduced intracellular levels of pituitary prolactin causing an increased mitotic response (Lloyd et al 1975).…”