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United States Department of Agriculture

Agricultural Research Service

Title: Orexin-B Modulates Lh and Gh Secretion: Interaction with the Brain-Pituitary Axis in the Pig.

Authors
item Barb, Claude
item Barrett, John
item Kraeling, Robert
item Matteri, Robert

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2003
Publication Date: June 22, 2003
Citation: Barb, C.R., Barrett, J.B., Kraeling, R.R., Matteri, R.L. Orexin-B modulates LH and GH secretion: interaction with the brain-pituitary axis in the pig. Journal of Animal Science. 2003. v. 81(Suppl.1): Abstract p. 101.

Technical Abstract: Two experiments (EXP) were conducted to test the hypothesis that orexin-B affects LH and GH secretion. In EXP I, prepuberal gilts received intracerebroventricular (ICV) injections of 0.9% saline (S; n = 2), 10 ug (n = 2) or 100 ug (n = 2) of orexin-B in S. Blood was collected every 15 min for 2 hr before and 2 hr after ICV injections. In EXP II, anterior pituitary cells from prepuberal gilts were studied in primary culture. On d 4 of culture, 100,000 cells/well were challenged with 0.1, 10 or 1000 nM GnRH; 10, 100 or 1000 nM hGRF-(1-29)NH2 or 0.01, 0.1, 10 or 100 nM , orexin-B individually or in combinations with 0.01 and 1000 nM GnRH or 10 and 1000 nM GRF. Secreted LH and GH were measured at 4 hr after treatment. In EXP I, serum LH and GH concentrations were similar among pigs before treatment and were unaffected by orexin-B treatment; averaging 0.5 ± 0.2, 1.0 ± 0.2 and 1.0 ± 0.2 ng/ml for LH and 2.1 ± 3.4, 6.1 ± 3.4 and 5.8 ± 3.4 ng/ml for GH after ICV injection of S, 10 ug or 100 ug orexin-B, respectively. In EXP II, basal LH and GH secretion (control; n = 9 wells) was 183 ± 18 and 108 ± 4.8 ng/well, respectively. Relative to control at 4 hr, all doses of GnRH and GRF increased (P < 0.001) LH and GH secretion. All doses of orexin-B increased (P < 0.001) GH secretion, while only the 0.010 nM dose increased (P<0.005) LH secretion. Secreted LH and GH were unaffected by addition of 0.01, 0.1, 10 or 100 nM orexin-B in combinations with 0.01 and 1000 nM GnRH or 10 and 1000 nM GRF compared to GnRH or GRF alone, except 0.1 nM orexin-B suppressed (P<0.02) the LH response to 1000 nM GnRH. These results indicate that orexin may directly modulate LH and GH secretion at the level of the pituitary gland, but not the brain.

Last Modified: 10/23/2014
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