A gonadotropin-like thermostable peptide, prepared from bovine anterior pituitary, inducing spermiation in the frog Rana esculenta (L.) and binding to a rat ovarian FSH receptor

Dopamine regulation of testicular activity in intact and hypophysectomized frogs, Rana esculenta

In intact frogs, both GnRHA and L-dopa were able to increase testicular and plasma androgen levels and to induce spermiation. The dopamine antagonist pimozide inhibited both the effects of L-dopa but not those of GnRHa. Hypophysectomy reduced androgen levels, but spermiation was still induced by both GnRHa and L-dopa, suggesting that these agents can directly influence the testis through a route not involving the pars distalis. Again, pimozide antagonised spermiation induced by L-dopa but not that induced by GnRHa.

A gonadotropin releasing hormone analog induces spermiation in intact and hypophysectomized frogs, Rana esculenta

The sperm-releasing activity of a gonadotropin releasing hormone (GnRH) agonist, Buserelin (GnRH) and hypophysis homogenate (PD) preparations was studied in intact and hypophysectomized (PDX) frogs, Rana esculenta. In addition, human chorion gonadotropin (hCG) was tested in PDX animals, and GnRH antagonist (GnRHA) treatments were carried out in intact and PDX animals, in combination with the hormonal injections. GnRH or PD treatments were able to elicit spermiation in intact and PDX animals. While GnRH, injected 24 h later, was again effective in inducing spermiation in intact animals, this was not the case in PDX frogs. GnRHA counteracted GnRH effects in intact frogs. Moreover, in PDX animals GnRHA injections counteracted the sperm-releasing activity induced by hCG or GnRH, but failed to inhibit sperm-releasing activity induced by PD homogenate.

Characterization of a thermostable LH-immunoreactive material from bovine pituitary gland

A thermostable peptide, immunologically similar to the beta-subunit of ovine lutropin, was isolated from a heated extract of bovine pituitary glands. The relative molecular mass of the peptide as well as its amino acid composition differed significantly from the lutropin subunits. Antibodies were raised to a preparation of this peptide.

Evaluation of several strategies for preparing a bovine gonadotropin-like peptide using isotachophoresis, isoelectrofocusing and high-performance liquid chromatography

Several strategies for preparing a gonadotropin-like, thermostable peptide from the bovine adenohypophysis were compared. Initially, we extracted bovine pituitaries, in the form of an acetone powder, with acetic acid and water. Using one strategy, we isolated the peptide from the crude extract by gel filtration, isotachophoresis, and isoelectrofocusing. The yield was ca. 50 micrograms of peptide from 100 pituitaries. Using another strategy, we isolated the peptide from the crude extract by precipitating the active material with ethanol followed by high-performance liquid chromatography (HPLC). The yield was ca. 500 micrograms of peptide from 100 pituitaries. Using analytical HPLC, we found that material obtained using the different strategies gave similar results. The HPLC route was, however, more efficient and faster than the other routes, and we recommend it for preparing this gonadotropin-like peptide.