English
General description
Glycoprotein hormone consisting of a 92-amino acid α-chain which is identical to that of LH, FSH, and TSH; and a distinct 149-amino acid β-chain. Produced by chorionic tissue and responsible for maintaining the corpus luteum during early pregnancy. Also produced by trophoblast cell neoplasms, which are marked by elevated free hCG β-chains and hyperglycosylated hCG.
Application
Chorionic gonadotropin has been used:
in in vitro analysis of cytotoxicity[1]
in egg and embryo preparations[2]
in the superovulation of CD-1 mice[3]
in gonadotropin preparations for the in vivo studies with the luteinizing hormone-releasing hormone (LHRH) agonist (LHRH-a) to synchronize naturally cycling rats.[4]
Biochem/physiol Actions
Human chorionic gondadotropin (hCG) may be used as an alternative to PMSG to induce ovulation in laboratory animals.[5] When hCG was injected into laboratory animals via intravenous (i.v.), intraperitoneal (i.p.), or subcutaneous (s.c.) methodstet, the effective dose values for 50% of the animals (ED50) per animal and per body weight (kg) in parenthesis were as follows:
Mice: i.v. 0.2 (7.7) I.U.; i.p. 0.3 (11.5) I.U.; s.c. 0.7 (26.9) I.U.
Syrian hamsters: i.v. 1.0 (9.5) I.U.; i.p. 1.8 (17.1) I.U.; s.c. 2.6 (24.8) I.U.
Rats: i.v. 1.3 (4.6) I.U.; i.p. 3.5 (12.3) I.U.; s.c.7.5 (26.3) I.U.
Using PMSG, the ED50 values per animal and per body weight (kg) in parenthesis were as follows:
Mice: i.v. 0.8 (30.8) I.U.; i.p. 2.0 (76.9) I.U.; s.c. 2.8 (107.7) I.U
Syrian hamsters: i.v., 3.6 (34.3) I.U.; i. p., 8.0 (76.2) I.U.; s.c., 13.2 (125.7) I.U.
Rats: i.v., 6.0 (76.8) I.U.; i p., 20.8 (73.0) I.U.; s.c., 76.8 (269.5) I.U.
Preparation Note
When reconstituted with 10 mL water to a concentration of 1,000 IU/mL, the vial will also contain 0.01 M sodium phosphate buffer (pH approx. 7.2) and 10 mg/mL of mannitol.
Analysis Note
The calculated value is based on the USP method for human Chorionic Gonadotrophin, to meet 10,000 IU per vial, with a tolerance of not less than 80.0% and not more than 125.0% of the potency stated.
