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Title: THE ONTOGENY OF INSULIN-LIKE GROWTH FACTOR-I (IGF-I) MODULATION OF GH SECRETION FROM PORCINE ANTERIOR PITUITARY CELLS IN CULTURE

Author
item Barb, Claude
item Hausman, Gary

Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2006
Publication Date: 7/20/2006
Citation: Barb, C.R., Hausman, G.J. 2006. The ontogeny of insulin-like growth factor-I (IGF-I) modulation of GH secretion from porcine anterior pituitary cells in culture [abstract]. Joint Abstracts of the American Dairy Science and Society of Animal Science. 89(1):347. W149.

Interpretive Summary:

Technical Abstract: The ontogeny of IGF-I modulation of GH secretion from the anterior pituitary was studied. Anterior pituitary cells collected from 110 day old fetuses (n =4), 2- (n = 7), 4- (n =8) and 6- (n = 7) month old gilts were studied in primary culture. On day 4 of culture, 100,000 cells/well were challenged with 0.1, 10 or 1000 nM [Ala15]-hGRF-(1-29)NH2 , 0.01, 0.1, 1, 10, 30 nM IGF-I individually or in combinations with 1000 nM GRF. Secreted GH was measured at 4 h after treatment. Basal (control) GH secretion was 267 ± 46, 76 ± 8, 39 ± 3 and 40 ± 7 ng/well for fetal, 2-, 4- and 6 month old animals, respectively. Relative to control at 4 h, all doses of GRF increased (P < 0.0001) GH in fetal pituitary cultures. Only 1000 nM GRF increased (P < 0.001) GH secretion in pituitary cultures from 4- and 6-month old pigs whereas pituitary cultures from 2 month old pigs did not respond to GRF. All doses of IGF-I increased (P < 0.04) basal GH secretion except for 0.01 nM in fetal pituitary cultures. Only the 1, 10 and 30 nM IGF-I increased (P < 0.04) basal GH secretion in pituitary cultures from 6 month old gilts. All doses of IGF-I failed to effect GH secretion in pituitary cell cultures from 2- and 4- month old gilts. Only 0.1, 10 and 30 nM IGF-I enhanced (P < 0.01) GH response to 1000 nM GRF from fetal pituitary cells in cultures. In pituitaries from 2 month old pigs only 30 nM IGF-I enhanced (P < 0.02) the response to 1000 nM GRF. All doses of IGF-I failed to influence the GH response to 1000 nM GRF in pituitary cultures from 4- and 6 month old pigs. These results demonstrate that GRF and IGF-I modulation of GH secretion is age dependent and occurred independent of hypothalamic input.