D Gourdji

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The effects of thyrotropin-releasing hormone and 17 beta-estradiol on the electrical membrane properties of a prolactin-secretin pituitary cell line (GH3/B6) were studied with intracellular microelectrode recordings. Of the cells tested, 50 percent were excitable and displayed calcium-dependent action potentials when depolarized. When injected directly on(More)
The in vivo internalization of thyrotropin-releasing hormone (TRH) was studied by using a semiquantitative immunoelectron microscopic method. Pituitary glands of normal male rats intravenously injected with 100 ng TRH and sacrificed after 5-60 min were used. Ultrathin sections were obtained by cryoultramicrotomy of fixed pituitary glands. Pituitary cellular(More)
In the present report, we have investigated the role of DNA methylation on the binding and trans-acting properties of transcription factors involved in the regulation of the rat prolactin (rPRL) gene, specifically Pit-1. To this aim we took advantage of a model system composed of three GH3 rat pituitary tumor cell lines that greatly differed in the extent(More)
Secretory activity of the anterior pituitary gland is regulated by the brain through stimulatory and inhibitory substances released from nerve endings in the median eminence of the hypothalamus and carried by the adenohypophysial portal blood system to their respective target cells. These hypothalamic influences are modulated by the feedback action of(More)
The lysosomotropic agent, chloroquine, has been used to investigate the implication of lysosomal activity and membrane traffic in TRH binding, TRH internalization and TRH-induced stimulation of prolactin secretion in a rat prolactin cell line (GH3/B6). Chloroquine by itself does not affect cell number, cell protein and basal prolactin secretion. It does not(More)
GH3/B6 rat prolactin cells were used to analyse at the cellular level the mechanisms by which 17 beta-estradiol (E2) regulates TRH responsiveness of prolactin cells. Before experiments, cells were grown for up to 7 days in 3 different media: normal medium (N) containing 15% horse serum and 2.5% fetal calf serum, CD medium prepared with charcoal-dextran(More)
In mammosomatotropes GH3B6 cells, one of the primary responses to thyrotropin-releasing hormone (TRH) is the parallel induction of two proto-oncogenes, c-fos and jun B, which code for constituents of AP1 transcription factor. To better understand the mode of action of TRH and to look for possible functions of c-fos and jun B in these cells, we have(More)
cDNA encoding the thyrotropin-releasing hormone receptor (TRH-R) was recently cloned in rat pituitary prolactin cells and in mouse thyrotropes. The molecular weights of the protein sequences obtained are 46.6 and 44.5 kD. However, TRH-R has not yet been purified to homogeneity and specific anti-TRH-R antibody could not yet be obtained by classical(More)
The hypothalamic neuropeptide TRH stimulates PRL release and PRL gene transcription in GH3B6 rat pituitary cells. In this model, TRH also raises c-fos proto-oncogene mRNA levels. c-fos is assumed to be involved in the transduction of external signals to the nucleus as a component of AP1 transcription factor, a complex that contains a member of the jun(More)