Isolation and properties of subunits of rat pituitary luteinizing hormone

Ward, Darrell N.; Reichart, Leo E.; Fitak, B; Nahm, Hyun S.; Sweeney, Carolyn M.; Neill, J. D.

doi:10.1021/bi00786a010

Cited by 34 publications

(3 citation statements)

References 36 publications

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“…These results clearly indicate that, in the rat pituitary gland, lutropin exists in at least two forms. Previous reports on the mol wt of human pituitary lutropin have shown a wide range between 25000 to 45000 with 2-4 protein com¬ ponents (Graesslin et al 1973;Roos et al 1975;Rabinowitz et al 1974;Ward et al 1971). …”

Section: Discussionmentioning

confidence: 94%

Existence of multiple molecular forms of luteinizing hormone in rat: differences in immunological and biological activities between stored and circulating forms

Reddy

Menon

1981

Acta Endocrinologica

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LH from rat anterior pituitary and serum was characterized with respect to its molecular size, and immunological and biological activity. Pituitary extracts prepared by homogenization followed by high speed centrifugation and chromatography on Ultrogel (AcA 44, 1.5 \m=x\80 cm) columns showed two peaks of radioimmunoassayable lutropin (LH) activity, a major peak 1 and a minor peak 2. On the basis of their elution from Ultrogel columns, peak 1 had a larger molecular size (Kav = 0.44) than peak 2 (Kav = 0.53). The biological activities of the two peaks were assessed by testing the ability of the two peaks to stimulate cAMP production and progesterone synthesis using immature rat ovarian cells. Both cAMP production and progesterone synthesis by ovarian cells were stimulated by peak 1 and peak 2 in a dose dependent manner, but differed in the degree of stimulation. At optimal concentrations, stimulation of cAMP production by peak 2 was 1.45-fold higher than peak 1. Similarly, stimulation of progesterone production by peak 2 was 2-fold higher than that produced by peak 1. The molecular size of the LH released from anterior hemipituitaries in response to a gonadoliberin (LRH) agonist, [Des-gly-NH210]LRH ethylaminde, was also determined. Chromatography of control medium as well as the agonist treated medium on the Ultrogel columns showed a single peak of LH activity at a position which corresponded to peak 1 found in the pituitary extract. However, the elution profile of serum LH from animals injected with LRH agonist was found to be similar to that of peak 2 of the pituitary extract. Incubation of the pituitary extract with serum resulted in a shift in the position of elution of peak 1 towards peak 2. From these studies it is concluded that the anterior pituitary contains a major high mol wt form of LH with lower biological activity and a minor low mol wt form with higher biological activity, but only the low mol wt form appears in the circulation.

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Section: Discussionmentioning

confidence: 94%

Existence of multiple molecular forms of luteinizing hormone in rat: differences in immunological and biological activities between stored and circulating forms

Reddy

Menon

1981

Acta Endocrinologica

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“…Perhaps the difference is attribut¬ able to the relative stability of the native hor¬ mones. It is known that rLH is fairly easy to dissociate (Ward et al 1971;Keel & Grotjan 1987). Thus, it is possible that the uncombined rLHß found in the medium may not have been released in the uncombined form but may have been derived from the dissociation of native rLH.…”

Section: Discussionmentioning

confidence: 99%

“…Additional characterizations were previously presented (Grotjan et al 1984(Grotjan et al , 1985. rLH, rFSH, rLHa and rLHß were quantitated with homologous assays and expressed in terms of rLH-DNW-8-59B (Ward et al 1971), rFSH-I4, rLHa-C043 and rLHß-A805 equivalents, respectively. FSHß was quantitated in a heterologous assay utilizing antirFSHß-57371658 and hFSHß-2 as the standard and hormone for iodination.…”

Section: Radioimmunoassaysmentioning

confidence: 99%

Quantitation of uncombined gonadotropin subunits within and released by the rat anterior pituitary

Grotjan

1988

Acta Endocrinologica

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The release of uncombined gonadotropin subunits by rat anterior pituitaries during an in vitro incubation as well as intracellular concentrations were assessed. Uncombined subunits and native gonadotropins were quantitated by radioimmunoassays after samples were subjected to gel filtration on Sephadex G-100 Superfine. Small, but detectable, amounts of uncombined rat LH \ g=b\ subunit were released under basal conditions. GnRH increased the absolute amount of rLH\g=b\ released but did not alter the rLH\g=b\/rLH molar ratio ( \ m=appr ox\ 0.02). Tissue extracts prepared in aqueous buffer (100 000 \m=x\ g supernatants) and 0.5% Triton X-100 extracts of the 100 000 \ m=x\ g pellets from the initial homogenization ('pellet extracts') contained larger quantities of uncombined rLH\g=b\ as well as elevated rLH\g=b\/rLHmolar ratios ( \ m=appr ox\ 0.10 and \m=approx\ 0.20, respectively). Significant amounts of uncombined rLH\g=a\were released and were present in both tissue and pellet extracts. However, when FSH \ g=b\ subunit was quantitated in tissue extracts after gel filtration, all of the immunoreactive materials eluted in the position of native rFSH (FSH\g=b\/rFSH molar ratio < 0.0025). Pellet extracts contained significant amounts of rLH\g=b\, rLH and rLH\g=a\but lesser amounts of rFSH suggesting that intracellular gonadotropins are not completely extracted when homogenization is performed in aqueous buffers. Thus, rat anterior pituitaries contain and release significant amounts of the uncombined \ g=a\ subunit, relatively small amounts of uncombined rLH\g=b\ and extremely small amounts of uncombined FSH\g=b\, if any.

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The utility of antiserums to subunits of TSH and LH for immunochemical staining of the rat hypophysis

1972

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The objective was to assess the effectiveness of antiserums to the B-subunit of bovine TSH (thyrotropin) and a-and p-subunits of LH (luteinizing hormone) for immunochemical staining of rat pituitary cells and in so doing to acquire more information about the properties of the subunits. For the following reasons it was concluded that antiserum to TSH-/3 is specific for demonstration of TSH-cells. The morphology and distribution of the presumptive TSH-cells so revealed conform to the descriptions presented by other investigators who have used histological techniques. When pituitary TSH content was reduced by thyroidectomy or administration of propylthiouracil or thyroxine, the stainability of TSH-cells was reduced; it was increased with elevation of TSH content during rebound after cessation of propylthiouracil treatment. The effectiveness of anti-TSH-p was lost after absorption with bovine TSH.The specificity of antiserum to LH-P for demonstration of LH-cells was indicated since the cells demonstrated with it correspond to the gonadotropic cells described by others with respect to morphology, distribution and response to gonadectomy. Antiserum to LH-a, the nonspecific subunit of LH, permitted staining of both TSH-and LH-cells. The individuality of TSH-and LH-cells, as revealed immunochemically with antiserums to the respective specific P-subunits, was demonstrated by double staining and by comparison of adjacent sections stained with one of the two antiserums.

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Isolation and properties of subunits of rat pituitary luteinizing hormone

Cited by 34 publications

References 36 publications

Existence of multiple molecular forms of luteinizing hormone in rat: differences in immunological and biological activities between stored and circulating forms

Existence of multiple molecular forms of luteinizing hormone in rat: differences in immunological and biological activities between stored and circulating forms

Quantitation of uncombined gonadotropin subunits within and released by the rat anterior pituitary

The utility of antiserums to subunits of TSH and LH for immunochemical staining of the rat hypophysis

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