Endocrine Abstracts

Background: Sex-steroid feedback regulates gonadotropin (LH and FSH) secretion. Kisspeptin, a novel hypothalamic neuropeptide, stimulates gonadotropin secretion by stimulating GnRH secretion, and has been shown in animal models to play a central role in mediating sex steroid feedback.Hypothesis: As estrogen feedback occurs at both the hypothalamus and the pituitary in women, we hypothesized that the stimulatory effect of kisspeptin-10 would be dependent ...

Previously we have demonstrated up-regulated expression of COX-2 and enhanced synthesis of PGE2 in cervical carcinomas. (Sales et al. 2001. J. Clin. Endocrinol Metab. 86(5):2243-2249). Enhanced PGE2 synthesis as a consequence of COX-2 overexpression has been associated with various carcinomas and is regarded as a promoter of neoplastic cell proliferation and angiogenesis. In sexually active women growth and invasiveness of neoplastic cervical cells may be...

Ligands have different binding affinities for mammalian and non-mammalian GnRH receptors. We have investigated whether this is due to differences in ligand contact sites and/or configuration of the receptors.The majority of residues that are contact sites in the mammalian receptor are conserved across species and are located in the extracellular loops (ECL's). The different binding affinities of ligands to non-mammalian receptors may be due to different ...

The prokineticins (PK1 and PK2, also known as endocrine gland vascular endothelial growth factor [EG-VEGF] and Bv8 respectively), which bind to two closely homologous G-protein coupled receptors, PKR1 and PKR2, have been identified as novel angiogenic factors in endocrine tissue. However, little information is available on their expression and distribution in the uterus. The objectives of this study were to examine the expression and localisation of prokineticins and their rec...

Background: Kisspeptin is a neuropeptide central to the regulation of gonadotrophin secretion but recent studies have suggested more diverse roles in human physiology. Kisspeptin is a potent inhibitor of tumour metastasis and plays a role in placentation, both processes involving angiogenesis. In addition, Kisspeptin and its receptor, GPR54, have been identified in human blood vessels including aorta, coronary artery and umbilical vein, where they mediate vasoconstriction. We,...

Pituitary gonadotropes (LH and FSH producing cells) are simultaneously exposed to numerous stimuli, which exert multiple signalling pathways that cross-talk with the GnRH receptor (GnRHR). A model downstream effector system is the prostanoid family. Hence, prostanoid receptors and GnRHR might cross-talk and affect the biological responses of the gonadotropes. Here we report the expression of prostaglandin (PG) PGE2 receptors EP1, EP2, EP3 and EP4, the PGF2</sub...

The chicken gonadotropin-releasing hormone receptor (cGnRH-R) is notable for having a cytoplasmic carboxyl-terminal tail, which is not present in the mammalian GnRH-Rs. We have previously shown that the cGnRH-R undergoes rapid agonist-induced internalization, and requires the carboxyl-terminal tail for this process. To investigate the role of the carboxyl-terminal tail of the cGnRH-R in relation to its rapid internalization, and to identify the key residues involved, a series ...

Hyperprolactinemia is the most common cause of hypogonadotropic anovulation in women. It is related to an alteration of pulsatile GnRH secretion. This gonadotropic deficiency has been proposed to result from direct suppression of prolactin (PRL) on GnRH release but its mechanism remains unknown. Because GnRH neurons do not express unequivocally the PRL receptor, and are stimulated by kisspeptin (Kp) neurons which do express PRL receptors, we hypothesized that GnRH deficiency i...