title: Effect of the increase of steroid binding plasma levels after passive immunization against testosterone on the control of luteinizing hormone (LH) secretion in ovariectomized underfed dairy heifers.
abstract: The ability of passive immunization against testosterone to increase sex steroid binding levels in plasma and thus to overcome the negative feedback of oestradiol-17 beta (E2) on LH secretion in underfed heifers was investigated. Dairy heifers were ovariectomized and divided in 3 groups: high energy diet (H group, n = 4), low energy diet (L group, n = 3) and low energy diet + E2 implants (LE2 group, n = 4). Twenty-four h before injection of bovine immunoglobulins, the mean concentrations of LH were not different between H and L groups. LH baseline was lower (0.8 vs 1.1 ng/ml, P less than 0.03) and the median number of LH pulses was higher (10 vs 5, P less than 0.03) in H than in L group. E2 markedly decreased (P less than 0.01) the mean and basal concentrations of LH (0.27 ng/ml), and number of LH pulses (0) in the LE2 group (P less than 0.05). After injection of anti-testosterone immunoglobulins in the L group, mean and basal LH concentrations tended to decrease. The median number of LH pulses in the L group rose 8 days after immunization (5 vs 7 on day -1 and day +8, P less than or equal to 0.05). Amplitude of pulses tended to decrease after injection (P = 0.08). In the LE2 group, the mean concentration and baseline of LH were not affected by passive immunization against testosterone, while pulses of LH appeared at day +1 and rose (P = 0.07) at day +8 after immunization with 3.5 pulses.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: INRA, Station de Physiologie de la Reproduction, Nouzilly, France.
authors.forename: V
authors.initials: V
authors.lastname: Lermite
authors.forename: J
authors.initials: J
authors.lastname: Thimonier
authors.forename: R
authors.initials: R
authors.lastname: Dufour
authors.forename: M
authors.initials: M
authors.lastname: Terqui
mesh_terms: D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D004343:Drug Implants; D002149:Energy Intake; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D007116:Immunization, Passive; D007136:Immunoglobulins / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D010052:Ovariectomy / Q000662:veterinary; D012738:Sex Hormone-Binding Globulin / Q000032:analysis*; D013739:Testosterone / Q000276:immunology* / Q000378:metabolism
chemical_list: D004343:Drug Implants; D007136:Immunoglobulins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone