Related Experiment Video
Updated: Jun 25, 2026

Gonadectomy and Blood Sampling Procedures in the Small Size Teleost Model Japanese Medaka (Oryzias latipes)
Published on: December 11, 2020
Effects of Gonadotrophin-Releasing Hormone Variants on Reproductive Organs and Plasma Testosterone in the Male
G Ciarcia1, M Paolucci, V Botte
1Dipartimento di Biologia Evolutiva e Comparata and.
Abstract:
Abstract The effects of various gonadotrophin-releasing hormone (GnRH) forms (mammalian GnRH (mGnRH), chicken I GnRH (cGnRH-I), chicken II GnRH (cGnRH-II) and salmon GnRH (sGnRH)) on the genital apparatus and plasma testosterone level in the male lizard, Podarcis s. sicula, have been investigated. In short duration experiments (20 min to 76 h) GnRH forms did not affect testicular and epididymal morphology. A single dose (0.05 mug) of mGnRH, cGnRH-II and sGnRH, however, induced a rise in plasma testosterone after 20 to 40 min. Variable results were obtained in the animals given GnRH variants every 12 h for 3 days since mGnRH and cGnRH-I caused a decrease of circulating hormone; cGnRH-II and sGnRH a slight increase. Daily peptide administration, for 15 to 30 days, caused severe inhibition of both testicular and epididymal activity and a significant drop of circulating testosterone. In Podarcis s. sicula, species specificity of pituitary sensitivity to GnRH variants appeared to be low. On the other hand, this gland seemed to show some desensitization after chronic peptide administration.
Related Concept Videos
Testosterone: Functions and Regulation
Gonadal and Placental Hormones
In males, testosterone is the primary gonadal androgen. It plays a central role in the maturation of male reproductive organs — the penis and testes. Additionally, testosterone is instrumental in the development of secondary sexual characteristics — a deep voice as well as facial and pubic hair growth — and...
Overview of the Reproductive System
The gonads, or primary reproductive organs, produce gametes and sex hormones. In males, the testes produce spermatozoa and testosterone, which is responsible for developing secondary male sex characteristics, including a deeper voice, larger muscles, facial and body...
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Hormones of the Pituitary Gland
The most abundantly secreted hormone from the anterior lobe is the growth hormone, which controls overall growth by...
Spermatogenesis

