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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #141165
Title: DEVELOPMENT OF AN ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) FOR THE MEASUREMENT OF PLASMA GROWTH HORMONE (GH) LEVELS IN CHANNEL CATFISH: ASSESSMENT OF ENVIRONMENTAL SALINITY AND GH SECRETAGOGUES ON PLASMA GH LEVELS

Author
item DRENNON, K - UNIV. OF KENTUCKY
item MORIYAMA, S - KITASATO UNIVERSITY
item KAWAUCHI, H - KITASATO UNIVERSITY
item Small, Brian
item SILVERSTEIN, J - USDA/ARS/NCCCWA
item PARHAR, I - NIPPON MED. SCHOOL
item SHEPARD, B - UNIV. OF KENTUCKY

Submitted to: General and Comparative Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2003
Publication Date: 10/1/2003
Citation: Drennon, K., Moriyama, S., Kawauchi, H., Small, B.C., Silverstein, J., Parhar, I., Shepard, B. 2003. Development of an enzyme-linked immunosorbent assay (ELISA) for the measurement of plasma growth hormone (GH) levels in channel catfish: assessment of environmental salinity and GH-secretagogues on plasma GH levels. General and Comparative Endocrinology 133:314-322.

Interpretive Summary: Until now, researchers have been unable to accurately quantify growth hormone levels in channel catfish tissues. Because of this inability, progress in understanding the endocrine regulation of catfish growth has been slow. The research presented here describes the development and validation of a specific and sensitive assay, which provides for the accurate measurement of channel catfish growth hormone. In addition, through the validation of this assay, it was determined that the freshwater channel catfish responded to changes in salinity with an increase in growth hormone production, suggesting that growth hormone helps to regulate electrolyte balance in catfish. Also, channel catfish were found to respond to synthetic peptides known to induce growth hormone production in most mammals. With this new ability to measure catfish growth hormone, much can be learned about the mechanisms of growth hormone on catfish physiology and vice versa. Application of such knowledge will lead to improvements in selective breeding and culture techniques.

Technical Abstract: We report the development of a sensitive, and specific, competitive, antigen-capture enzyme-linked immunosorbent assay (ELISA) for the measurement of channel catfish growth hormone (cfGH). The detection limit of the assay was 2.0 ng/ml. Recovery of cfGH-spiked plasma samples averaged 102%, and dose-response inhibition curves were significantly parallel. The antibody used was shown to be specific for cfGH. To physiologically validate the assay, response of channel catfish to injections with either bovine GHRH or the synthetic hexapeptide GHRP-2 was determined for catfish exposed to either fresh- or brackish water (12 ppt). Plasma GH levels were significantly (p < 0.001) elevated in all the brackish water groups compared to freshwater groups. In addition, plasma GH levels were significantly (p < 0.001) elevated by treatment with either of the GH secretagogues. Our findings demonstrate that two regulatory mechanisms of GH elevation, one which is seen in euryhaline teleosts (salinity-induced GH levels) and another, which has been recently described in teleosts (GHRP-induced GH levels), are present in the stenohaline channel catfish.