title: Relationship of age and season and consumption of Senecio vulgaris to LH/hCG receptors in the stallion testis.
abstract: 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.
mesh_terms: 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*
chemical_list: D011974:Receptors, LH