Ovine luteinizing hormone heterogeneity: androgens increase the percentage of less basic isohormones.

The heterogeneity of luteinizing (LH) is hormonally regulated with androgens having been reported to increase the percentage of extremely basic LH isohormones in the ovine pituitary. This study re-examined the effects of androgens on the heterogeneity of LH in the ovine pituitary because the extremely basic isoforms of LH reported previously were subsequently demonstrated to be artifacts resulting from the conditions used for chromatofocusing. Pituitary extracts from wethers, rams, and dihydrotestosterone (DHT)-implanted wethers were desalted by flow dialysis and chromatofocused on pH 10.

Effects of 17 beta-estradiol on distribution of pituitary isoforms of luteinizing hormone and follicle-stimulating hormone during the follicular phase of the bovine estrous cycle.

The objective of this study was to examine the influence of 17 beta-estradiol (E2) on distribution of LH and FSH isoforms during the follicular phase of the bovine estrous cycle prior to the preovulatory surges of LH and FSH. On Day 16 of the estrous cycle (Day 0 = estrus), intact controls (CONT; n = 4) were treated with prostaglandin F2 alpha (PGF2 alpha) to induce luteal regression and initiation of the follicular phase. Other cows were also treated with PGF2 alpha and either ovariectomized (OVX; n = 5) or ovariectomized and given E2 implants (OVXE; n = 6) to mimic the pattern of increasing E2 concentrations during the follicular phase of the estrous cycle.

Heterogeneity of gonadotropins and levels of uncombined luteinizing hormone subunits in pituitaries of cryptorchid rams.

Pituitaries were collected from intact rams and rams that had been rendered bilaterally cryptorchid by surgery to examine the effects of cryptorchidism on gonadotropin heterogeneity, levels of uncombined luteinizing hormone (LH) subunits, and the apparent molecular sizes of LH and follicle-stimulating hormone (FSH). Cryptorchid rams had higher pituitary contents of LH and FSH as well as reduced testicular weights. The levels of uncombined LH subunits, their apparent molecular weights, and the apparent molecular weights of intrapituitary LH were similar in control and cryptorchid rams.

Effect of immunization against LHRH on isoforms of LH in the ovine pituitary.

The role of LHRH in modulating intrapituitary LH content as well as the distribution of LH among its isoforms was examined in sheep. Rams (n = 3) and wethers (n = 6) were actively immunized against an LHRH-human serum globulin conjugate. Pituitaries collected from these animals plus pituitaries from corresponding numbers of nonimmunized rams and wethers were extracted with a buffered saline solution containing protease inhibitors.

Ovine luteinizing hormone: isoforms in the pituitary during the follicular and luteal phases of the estrous cycle and during anestrus.

Pituitaries were collected from late follicular phase (n = 5), mid-luteal phase (n = 5), and anestrous ewes (n = 4) to assess changes in intrapituitary LH heterogeneity at selected reproductive states. After homogenization, an aliquot of each pituitary extract was desalted by flow dialysis against water and chromtofocused on a pH 10.5 to 4.