Existing research on the role of gonadotropin-releasing hormone (GnRH) in bivalve reproduction is inadequate, even though a few bivalve GnRH orthologs have been cloned. The objective of this paper was to elucidate the in vivo effect of GnRH administration in Yesso scallop reproduction. We performed in vivo administration of scallop GnRH (py-GnRH) synthetic peptide into the developing gonad, and...

The pattern of the gonadotropin-releasing hormone (GnRH) stimulus is critically important in the regulation of pituitary gonadotropin secretion and continuous infusions down-regulate secretion while intermittent pulses maintain luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responsiveness. We examined the effects of pulsatile GnRH administration on pituitary GnRH receptors (GnR...

In our previous studies, we demonstrated that ERK1/2 (extracellular signal-regulated protein kinase) and p38 MAPK (mitogen-activated protein kinase) are required for gonadotropin-releasing hormone (GnRH)-II-induced anti-proliferation of ovarian cancer cells. In the present study, we examined the role of the GnRH-I receptor, as well as the activation of protein kinase C (PKC), in the anti-prolif...

Gonadotrophin releasing hormone (GnRH) plays an important regulatory role in the function and growth of human placenta, but its placental expression sites and co-localization with GnRH receptor (GnRH-R) are not well known. GnRH and GnRH-R expression has been found in both placenta and cultured trophoblasts; however, cultured trophoblastic cells very quickly lose GnRH-R message and subsequently ...

Gonadotropin-releasing hormone 1 (GnRH1) from the brain controls reproduction in vertebrates via a GnRH-specific receptor in the pituitary; however, other forms of GnRH are found in all species, suggesting additional roles for this family of peptides. GnRH action depends critically on the location of its cognate receptors in the brain. To understand the potential roles of additional GnRH forms,...

The hypothalamic decapeptide gonadotrophin-releasing hormone (GnRH) binds to high affinity receptors on pituitary gonadotrophs. These receptors mediate the effects of GnRH on secretion and synthesis of gonadotrophins. The GnRH receptor is coupled to Gq/G11, which activates phospholipase C. This enzyme leads to the generation of several second messenger molecules. Among these, diacylglycerol (DG...

Two forms of gonadotropin-releasing hormone (GnRH), GnRH-I and GnRH-II, are commonly present in mammals. The main hormone controlling reproduction is GnRH-I acting through its receptor (GnRHR-I), whereas the function of GnRH-II is unknown. In primates, it has been suggested that GnRH-II is a specific agonist for the structurally distinct GnRHR-II. Here we compared effects of GnRH-I and GnRH-II ...

With the exception of modern mammals, most vertebrate species possess two GnRH genes, GnRH-1 and GnRH-2. In addition, in many teleost fish, there is a third gene called GnRH-3. If the main function of GnRH-1 is unambiguously to stimulate gonadotropin release, the other two GnRH forms still lack clear functions. This is particularly true for the highly conserved GnRH-2 that encodes chicken GnRH-...

Gonadotropin‑releasing hormone (GnRH), or its analogues have been demonstrated to exhibit anti‑proliferative effects on tumour cells in ovarian, endometrial and breast cancer through GnRH‑receptors (GnRH‑R). However, the role of GnRH in nasopharyngeal carcinoma (NPC) remains to be elucidated. In order to investigate the effects of GnRH in NPC, the present study examined the expression of the Gn...

Lamprey GnRH-I and lamprey GnRH-III are the only two members of the GnRH family to have substitutions in the sixth position, Glu6 and Asp6, respectively; all other GnRH peptides have Gly in the sixth position suggesting a different conformational structure. Thus, a structure-activity study of lamprey GnRH-I or analogs that were cyclized or with sixth position substitutions were determined in vi...