Relationship of age and season and consumption of Senecio vulgaris to LH/hCG receptors in the stallion testis.
Testes were obtained from 70 colts and stallions and were pooled according to age (4 months to 23 years) to determine the relationship of age to LH/hCG receptor kinetics. The receptor concentration (Rt) increased from 0.069 x 10(-11) M/mg crude membrane fraction (CMF) for the 4-14-month pools to 0.464 x 10(-11) M for the 2-3-year-old pools. A 10-fold increase in testicular size also occurred, and so the total number of receptors per testis was significantly increased. A further increase to 1.237 x 10(-11) M/mg CMF was observed for stallions older than 5 years. No differences in binding affinities (Ka) were observed for the various age groups: Ka values varied from 0.19 to 2.19 x 10(11) M-1. A seasonal effect was not (P less than 0.28) observed for Rt [0.74 x 10(-11) M vs 1.15 x 10(-11) M/mg CMF, winter (N = 5) vs summer (N = 4)] or for Ka (0.259 x 10(11) M-1 vs 0.393 x 10(11) M-1, winter vs summer). Immediately before death resulting from inadvertent long-term consumption of Senecio vulgaris, testes were removed from 5 stallions and pooled. An Rt of 0.046 x 10(-11) M/mg CMF was observed. Therefore, a decrease to 2.7% was observed when compared with values for normal stallions. The Ka, 0.036 x 10(11) M-1, was decreased to less than 10%. Stallions consuming sublethal amounts may have altered reproductive functions.
D000375:Aging / Q000378:metabolism*; D000818:Animals; D006736:Horses / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010939:Plant Poisoning / Q000209:etiology / Q000378:metabolism; D010947:Plants, Toxic; D011974:Receptors, LH / Q000378:metabolism*; D012621:Seasons; D012674:Senecio; D013737:Testis / Q000378:metabolism*
D011974:Receptors, LH