A radioimmunoassay for African catfish growth hormone: validation and effects of substances modulating the release of growth hormone.
A highly sensitive radioimmunoassay has been developed for measuring plasma growth hormone (GH) concentrations in the African catfish (Clarias gariepinus). The lower detection limit of the assay was 0.1 ng/ml and the standard curve had an ED50 value of 0.5 ng/ml. The validity of the assay was established and the effects of several neurotransmitters on the release of GH were examined. In vitro experiments, using a static culture system for dispersed pituitary cells, demonstrated that the GH release in African catfish was affected by growth hormone-releasing hormone and somatostatin. Single intraperitoneal injections with a dopamine agonist, apomorphine, produced significant and dose-dependent increases in plasma GH levels. Unlike carp, goldfish, and tilapia, a super-active analogue of salmon gonadotrophin-releasing hormone did not alter plasma GH levels in African catfish.
Lescroart
O
O
Laboratory of Comparative Endocrinology, Catholic University of Leuven, Louvain, Belgium.
Roelants
I
I
Mikolajczyk
T
T
Bosma
P T
PT
Schulz
R W
RW
Kühn
E R
ER
Ollevier
F
F
D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage; D002397:Catfishes; D002478:Cells, Cultured; D003429:Cross Reactions; D018491:Dopamine Agonists / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives; D013006:Growth Hormone / Q000032:analysis* / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D006727:Hormone Antagonists / Q000494:pharmacology; D007106:Immune Sera / Q000276:immunology; D007150:Immunohistochemistry; D007274:Injections, Intraperitoneal; D007457:Iodine Radioisotopes; D008297:Male; D010902:Pituitary Gland / Q000033:anatomy & histology / Q000737:chemistry / Q000166:cytology / Q000276:immunology; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017337:Sermorelin / Q000494:pharmacology; D013004:Somatostatin / Q000494:pharmacology
D018491:Dopamine Agonists; D006727:Hormone Antagonists; D007106:Immune Sera; D007457:Iodine Radioisotopes; D007987:Gonadotropin-Releasing Hormone; D013004:Somatostatin; D017337:Sermorelin; D013006:Growth Hormone; D001058:Apomorphine