Prolactin Secretion and Synthesis in Short- And Long-Term Organ Culture of Pituitary Tumours From Acromegalic Patients

Abstract

To evaluate the in vitro PRL secretion and synthesis by pituitary tumours from acromegalic patients, six somatotrophic and two somatomammotrophic adenomas were collected after surgery and divided into fragments 1 mm3 in size. Fragments were cultured in short-term ( 1\ p=n-\ 2\ p=n-\ 3\ p=n-\ 4 h) and in long-term organ culture (7 and 14 days). Media were collected for GH and PRL radioimmunoassay and fragments studied by electron microscopy. In two experiments, fragments from a somatotrophic adenoma and from a somatomammotrophic adenoma were cultured for 1 to 4 h and 9 to 16 days with [3H]leucine. In addition the effect of somatostatin (2.5 nmole/ml) upon PRL secretion was studied in short-term incubation. In long-term organ culture PRL concentrations increased in 8 out of 16 media samples collected from the five tumours and one normal pituitary cultured for 14 days, while GH concentrations decreased during the same time in all the experiments. The [3H] PRL/[3H] proteins ratios were 9.7 % on the 9th day of culture and 20.8 % on the 16th day while for GH, the ratios were respectively 40 and 34.7 %. Ultrastructural studies showed, besides GH cells, the presence of PRL secreting cells in the different tumours, after 7 or 14 days of culture. In short-term incubation, PRL concentrations in media increased in most of the samples collected from the three tumours incubated for 1 to 4 h and the [3H]PRL/[3H]proteins ratio was 10.6 % after 1 h and 21 % after 2 h of incubation. A decrease of PRL content (< 50 %) was observed in two of the three tumours incubated with somatostatin.These data indicate that 1) somatotrophic adenomas, as well as somatomammotrophic ones, are able to secrete and synthesize PRL in vitro,

The value of plasma prolactin levels in the prediction of the responsiveness of growth hormone secretion to bromocriptine and TRH in acromegaly

“…Peillon et al [20] showed from short-and long-term organ cultures of pituitary tumours from acromegalic patients that both somatotrophic adenomas as well as somatomammotrophic ones are capable of secreting and synthesizing PRL in vitro to a variable extent. Contradictory results have been reported as to the question whether 'mixed' pituitary adenomas are composed of one cell type that secretes both GH and PRL [18] or of two distinct, well-defined cell types, which do not represent different secretory phases of the same cell type [21].…”

Correlation between the number of thyroliberin binding sites, the tumour size and the plasma prolactin level in human prolactin-secreting adenomas

“…RIA of plasma Prl. Immunoreactive Prl was measured in plasma by a homologous double antibody RIA as de¬ scribed previously (Peillon et al 1978). Statistical analysis.…”

Growth Hormone Secreting Pituitary Adenomas Are Heterogeneous in Cell Culture and Commonly Secrete Glycoprotein Hormone Α‐subunit

“…This in-vitro study has shown that G H secreting pituitary adenomas are associated with the direct secretion of other anterior pituitary hormones apart from GH, and these include the structurally-related polypeptide PRL which is well recognized (Guyda el al., 1973;Peillon et al, 1978;Mashiter et al, 1979), and the unrelated glycoprotein hormone a-subunit. The secretion of a-subunit from the 12 tumours of Group 1 was associated with either very low or undetectable levels of LH or FSH.…”