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Application of the immunofluorescence technique and confocal laser scanning microscopy for studying the distribution of the luteinizing hormone/chorionic gonadotropin (LH/CG) receptor on rat luteal cells.

https://arctichealth.org/en/permalink/ahliterature65080
Source
J Histochem Cytochem. 1991 Apr;39(4):397-400
Publication Type
Article
Date
Apr-1991
Author
J T Lakkakorpi
H J Rajaniemi
Author Affiliation
Biocenter University of Oulu, Finland.
Source
J Histochem Cytochem. 1991 Apr;39(4):397-400
Date
Apr-1991
Language
English
Publication Type
Article
Keywords
Animals
Female
Fluorescent Antibody Technique
Image Processing, Computer-Assisted
Immunohistochemistry - methods
Lasers
Luteal Cells - metabolism - ultrastructure
Microscopy, Electron - methods
Pseudopregnancy - metabolism
Rats
Rats, Inbred Strains
Receptors, Gonadotropin - metabolism
Receptors, LH - metabolism
Research Support, Non-U.S. Gov't
Abstract
We used confocal scanning microscopy to study the semi-quantitative distribution of luteinizing hormone/chorionic gonadotropin (LH/CG) receptors on rat luteal cells at both the two- and the three-dimensional level. The receptors were visualized in 6-microns sections of pseudopregnant rat ovaries using polyclonal rabbit antiserum to hCG-affinity-purified LH/CG receptor in conjunction with rhodamine-conjugated anti-rabbit immunoglobulins. Twenty to 30 optical sections were taken at different focal planes from representative luteal cells with a confocal laser scanning microscope and then processed digitally to two- and three-dimensional pseudocolored images. Distinct differences in fluorescence intensity could be demonstrated at both the two- and the three-dimensional level on the luteal cell surfaces, suggesting an uneven distribution of the LH/CG receptors on the cell membranes. This probably results in the compartmentalization and polarization of luteal cell function.
PubMed ID
2005369 View in PubMed
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Human chorionic gonadotrophin (CG)-induced down-regulation of the rat luteal LH/CG receptor results in part from the down-regulation of its synthesis, involving increased alternative processing of the primary transcript.

https://arctichealth.org/en/permalink/ahliterature64837
Source
J Mol Endocrinol. 1993 Apr;10(2):153-62
Publication Type
Article
Date
Apr-1993
Author
J T Lakkakorpi
E M Pietilä
J T Aatsinki
H J Rajaniemi
Author Affiliation
Biocenter, University of Oulu, Finland.
Source
J Mol Endocrinol. 1993 Apr;10(2):153-62
Date
Apr-1993
Language
English
Publication Type
Article
Keywords
Animals
Base Sequence
Blotting, Northern
Chorionic Gonadotropin - physiology
DNA, Single-Stranded
Densitometry
Down-Regulation
Female
Humans
Immunoblotting
Molecular Sequence Data
Ovary - metabolism
Polymerase Chain Reaction
Pseudopregnancy - metabolism
RNA Processing, Post-Transcriptional
RNA, Messenger - metabolism
Rats
Rats, Sprague-Dawley
Receptors, LH - genetics - metabolism
Research Support, Non-U.S. Gov't
Transcription, Genetic
Abstract
To elucidate the molecular mechanisms involved in the homologous regulation of LH/chorionic gonadotrophin (CG) receptors, the receptor and its mRNA levels were analysed in the same pseudopregnant rat ovarian samples after human (h)CG-induced down-regulation using a binding assay, ligand blotting, immunoblotting and Northern blotting together with the polymerase chain reaction (PCR). Treatment of the animals with 500 IU hCG resulted in a loss of 125I-labelled hCG binding and the 90 kDa receptor on the ligand and immunoblots within 12 and 24 h respectively, followed by a transient partial recovery on days 4 and 5, while a distinct decline occurred only on day 7 in the controls. Northern blots of total ovarian RNA, as probed with a 293 bp AvaI/HindIII fragment from the extracellular domain of PCR-generated full-length rat LH/CG receptor cDNA, revealed six major mRNAs of 7.0, 4.2, 2.8, 2.0, 1.4 and 1.1 kb. The 4.2 kb mRNA, which was the most abundant, possibly encodes the 90 kDa receptor, while the smaller species probably represent alternatively spliced forms of the LH/CG receptor pre-mRNA, as also supported by the finding that PCR produced three cDNA bands of 2.1, 2.0 and 1.8 kb when oligomers derived from the N and C termini of rat LH/CG receptor cDNA were used as primers and rat ovarian total RNA as a template. Treatment with hCG led to the down-regulation of all six mRNAs in a fashion parallel to the changes in receptor protein. No smaller receptor components capable of binding radiolabelled hCG or receptor antibody appeared on the ligand or immunoblots prior to or during down-regulation or the subsequent transient period of up-regulation, suggesting that the smaller mRNA species are translated in minute amounts in vivo or are not translated at all. Laser densitometric analysis of the Northern blots revealed that the amounts of the four smallest mRNA species increased during the period of down-regulation in relation to the 4.2 kb mRNA, and correspondingly decreased during the subsequent period of up-regulation, indicating changes in the alternative splicing of the primary transcript. The data suggest that hCG-induced transient down-regulation of the LH/CG receptor results in part from down-regulation of its mRNA levels, and that changes in alternative processing of the receptor pre-mRNA may play a regulatory role in the expression of functional LH/CG receptor during down- and up-regulation.
PubMed ID
8484864 View in PubMed
Less detail