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Title: DIFFERENTIAL PITUITARY AND GONADAL FUNCTION OF CHINESE MEISHAN AND EUROPEANWHITE COMPOSITE BOARS: EFFECTS OF GONADOTROPIN-RELEASING HORMONE STIMULATION, CASTRATION, AND STEROIDAL FEEDBACK

Author
item WISE, THOMAS
item LUNSTRA, DONALD
item FORD, JOHNY

Submitted to: Biology of Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: The pituitary gland makes chemicals called hormones that affect reproduction, growth, and health of animals. An understanding of how the pituitary is regulated and how it functions will ultimately lead to improved domestic animal production. Studies were conducted to determine different regulatory aspects of pituitary function in Chinese Meishan and European crossbred boars. Both breeds were equally sensitive to gonadotropin releasing hormone and feedback effects of testicular steroids. Follicle stimulating hormone and luteinizing hormone were increased in Meishan boars and may be related to increased fecundity noted in the Meishan breed. Such information indicates pituitary hormones play an important role in growth, health, and reproduction and understanding regulation may improve animal production efficiency.

Technical Abstract: In defining possible mechanisms that relate to the considerable breed differences in concentrations of gonadotropins in Chinese Meishan boars and meat-type crossbred boars of European origin, sensitivity to GnRH challenge, hormonal clearance, and gonadal pituitary feedback effects were monitored in two experiments. In the first trial, jugular catheters were placed into mature Meishan (n=7) and crossbred boars (n=8). Boars were repetitively sampled after two dosages of GnRH were administered (150 and 1500 ng/kg BW) a wk apart. Prior to GnRH, FSH was greater in Meishan boars (554+/-50 vs 102+/-8 ng/ml, p<0.01). Both breeds responded with increases in FSH, LH, and testosterone, but concentrations of gonadotropins in Meishan boars were increased longer than crossbred boars (by 160 min post GnRH, gonadotropins were declining in crossbred boars). Maximal plasma concentrations of FSH after GnRH stimulation was greater in the higher than nin the lower GnRH challenge (1058+/-113 vs 730+/-70 in Meishan and 184+/-4 vs 141+/-14 ng/ml in crossbred boars). Differences in concentrations of gonadotropins in Meishan and crossbred boars of European origin seem to be at the pituitary level of control and not related to gonadal factors.