In Vivo Bioactivities and Kinetic Parameters of Rat Luteinizing Hormone Components: Discrepancy Between In Vivo and In Vivo Assays.

Abstract

Abstract.Rat pituitary LH shows an electrical charge heterogeneity owing to their carbohydrate moiety. The biological potencies of these isoelectric components increase with increasing pi when examined by in vitro testosterone production in isolated rat Leydig cells. The present study was carried out to clarify if this tendency was also true with of in vivo action and to estimate their kinetic parameters. Seven isoelectric components of LH, i.e. X (pI 7.9), A (8.4), B (8.8), C (9.1), D (9.3), E (9.6) and F (9.8), were administered to cannulated adult male rats. Blood samples were serially collected over a 5 h period from the conscious animal, and rat LH and testosterone were assayed by RIA. The doses of a single component showed a linear relationship with the areas under the curve (AUC) of the blood LH. The testosterone AUC also correlated well with LH AUC. It was found that the components with lower pls had longer half-lives and larger LH AUC, and smaller total body clearance rates with highly significant correlation coefficients.The in vivo bioactivities of the components expressed as testosterone AUC increased with decreasing pIs, indicating that the in vivo bioactivity was much influenced by the total body clearance rate. The intrinsic activities of the components were calculated as ratios of testosterone AUC to LH AUC where the effect of the clearance rate (or biological half-life) was eliminated. The intrinsic activities of components were not significantly different among the components except component X which showed a smaller activity. These data indicated that, with the exception of component X, an LH component with a lower pI has a longer biological half-life, resulting in a higher in vivo potency, quite contrary to the tendency of in vitro potency.Key words: Charge heterogeneity, Rat LH, In vivo activity (Endocrine Journal 45: 307-314,1998) LH is a glycoprotein hormone consisting of two non-covalently linked subunits, a and f3. The asubunit contains two N-linked oligosaccharides, and the fl-subunit contains one such oligosaccharide [1]. Depending on the differences in isoelectric points (pls), rat pituitary LH can be separated into

Silymarin abrogates acrylamide‐induced oxidative stress‐mediated testicular toxicity via modulation of antioxidant mechanism, DNA damage, endocrine deficit and sperm quality in rats

“…The Japanese Shibayagi Company rat ELISA kit (Cat No. AKRLH-10) was used for the determination of LH in rat serum according to Shioya and Wakabayashi (1998) procedures. The quantitative determination of serum LH followed procedures for LH ELISA Kit in a sandwich ELISA system.…”

Resveratrol Mitigates Diabetic Testicular Dysfunction, Endocrine Deficits, and Insulin Resistance via Suppression of Sperm-Endocrine Aberrations and Oxidative Inflammation in Rats

“…Luteinizing hormone levels were estimated with the Japanese Shibayagi Company Rat ELISA Kit (Cat No. LH-10) according to Shioya and Wakabayashi [31] method, while follicle-stimulating hormones were assessed using commercial kits (Cat No. E-EI-M0511) based on the method of Teerds et al [32] protocols from BioVendor, Tokyo, Japan.…”