High impact information on GRP

• Quantitative ligand displacement analysis using various unlabeled GRPr agonists shows a rank order of potency characteristic of the GRPr: bombesin > or = GRP > > neuromedin B [1].
• Reconstitution of urea extracted membranes with a purified G alpha q showed that receptor-catalyzed binding of GTP gamma S was dependent on agonist (GRP) and G beta gamma subunits [1].
• The EC50 for GRP was 3.5 nM, which correlates well with the reported Kd of 3.1 nM for GRP binding to GRPr expressed in mouse fibroblasts [Benya, R. V., et al. (1994) Mol. Pharmacol. 46, 235-245] [1].
• It remains to demonstrate whether the parallel down-regulation of GRP 78 and type II collagen observed here corresponds to a co-ordinate regulation of these two proteins [2].
• The normal rise in plasma pancreatic polypeptide concentration in response to GRP was invariably abolished in the presence of amino acids [3].

Biological context of GRP

• These findings suggest that GRP may be important both in the endometrial remodeling during the estrous cycle and in the implantation and development of blastocysts [4].
• In metestrus and diestrus stages, GRP was also detected in the superficial epithelial cells of horn, but not in the body [4].
• During the early gestational period, GRP immunoreactivity was detected at relatively similar intensity to the follicular phase [5].

Anatomical context of GRP

• Positive staining of GRP immunoreactivity in the uterine gland epithelial cells was detected in both the uterine horn and body from all stages of the cycle [4].
• Recently, the localization of GRP in mammalian uterus and placenta has been demonstrated [6].
• In situ hybridization results ascertained the expression of the GRP mRNA in the uterine gland epithelial cells and superficial epithelial cells of the endometrium [4].
• At the electron-microscopic level, the supranuclear secretory granules and the secreted materials on the surface of the cell were labeled with immunogold particles representing GRP immunoreactivity in the uterine gland cells of nonpregnant and pregnant cows [6].
• In situ hybridization results ascertained the expression of GRP mRNA in the superficial epithelial cells of the cervix of non-pregnant and pregnant cows [5].

Associations of GRP with chemical compounds

• In the fetus, adult non-pregnant and pregnant specimens, GRP and GRP mRNA were predominantly detected in the luminal epithelial cells of basal areas of peripheral regions of the cervix [5].
• These responses were associated with a rise in plasma glucose concentration which could not be attributed to a direct action of GRP on the liver [7].
• VIP-, SP-, and LENK-IR nerves were detected in all segments, whereas GRP- and SOM-IR nerves were detected only in the reticular groove [8].
• In the placenta, strong immunoreactivity for GRP was demonstrated in the uterine gland epithelial cells; moderate in superficial epithelial cells; and weak in the trophoblasts, trophoblastic giant cells and cryptal epithelial hybrid cells [9].

Other interactions of GRP

• The rise in mean plasma glucagon concentration in response to GRP that occurred in the control group, the group pre-treated with amino acids alone and the group given both glucose and amino acids, was virtually eliminated in the group pre-treated with glucose alone [3].
• No significant change in either mean neurotensin-like or gastric-inhibitory-peptide-like immunoreactivity was observed in response to GRP in any of these groups [3].
• GRP, but not bombesin, produced a small but significant rise in the mean plasma somatostatin concentration [7].
• The distribution of nerves containing immunoreactivity for substance P (SP), vasoactive intestinal polypeptide (VIP), leucine-enkephalin (LENK), and gastrin-releasing polypeptide (GRP) in the margin of the reticulo-omasal orifice, omasum, and omasal pillar of calves and cows was studied by immunohistochemistry [10].

Analytical, diagnostic and therapeutic context of GRP

• RT-PCR showed the expected GRP mRNA fragments (284 bp) in the tissues from all stages of the cycle [4].
• Western blotting analysis showed a larger molecular form of GRP in the endometrial tissues taken from nonpregnant and pregnant cows [6].
• SP and GRP immunoreactivities coeluted with their synthetic counterparts from both Sephadex G-50 and reversed phase HPLC columns [11].
• Isolation and high performance liquid chromatography (HPLC) analysis of adrenomedullary ir-bombesin revealed the presence of four molecular forms, one of them corresponding to gastrin releasing peptide (GRP), another one (major peak) eluting closely to synthetic neuromedin B and another one coeluting with GRP-(18-27) [12].
• Alcoholic extracts of bovine mesenteric lymphatic vessels were assayed for the presence of SP, GRP, VIP, PHI, GIP and NT using specific radioimmunoassays [11].

References