Document Detail

Ontogeny of the inhibitory guanine nucleotide-binding regulatory protein in the rat testis: mRNA expression and modulation of LH and FSH action.
MedLine Citation:
PMID:  7926274     Owner:  NLM     Status:  MEDLINE    
The ontogeny of function and mRNA expression of the inhibitory guanine nucleotide-binding regulatory protein (Gi) was studied in the rat testis. Dispersed testis cells of animals aged 8, 15, 20 and 30 days were cultured with or without 100 micrograms/l pertussis toxin (PT) for 24 h. The cells were then cultured for another 24 h with medium only, cholera toxin (CT), PT, or their combination, and the amount of testosterone and cAMP production was measured. PT preincubation increased CT-stimulated cAMP production at all ages, thus indicating the presence of a functional Gi-protein in the postnatal testis. However, when testosterone production was measured, the enhancing effect of PT was absent at the age of 8 days only, indicating that Leydig cells at this age did not have functional Gi-protein. We then cultured 2-day-old and 8-11-day-old testis cells, after 24 h pretreatment with PT, in the presence of ovine follicle-stimulating hormone (FSH) (1 mg/l). The FSH-stimulated cAMP production was enhanced at both ages, thus indicating the presence of a functional Gi-protein in neonatal Sertoli cells. In Northern blot analyses, fetal and postnatal testis tissue had very similar levels of G alpha i2 and G alpha i3 mRNAs; the mRNA level of Gi1 in Northern blots remained low compared to those of Gi alpha 2 and Gi alpha 3. In conclusion, the Gi protein appears in the developing rat testis in utero but the activity first seems to be confined to non-Leydig cells including the Sertoli cell. In Leydig cells, the functional Gi-protein appears between days 8-15 post partum. This finding may be related to the fact that the fetal-neonatal population of Leydig cells possesses a high steroidogenic capacity and an apparent lack of the ability to respond to high gonadotropic stimulation with LH receptor down-regulation and steroidogenic enzyme desensitization.
V Eskola; A Rannikko; I Huhtaniemi; D W Warren
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular and cellular endocrinology     Volume:  102     ISSN:  0303-7207     ISO Abbreviation:  Mol. Cell. Endocrinol.     Publication Date:  1994 Jun 
Date Detail:
Created Date:  1994-11-01     Completed Date:  1994-11-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7500844     Medline TA:  Mol Cell Endocrinol     Country:  IRELAND    
Other Details:
Languages:  eng     Pagination:  63-8     Citation Subset:  IM    
Department of Physiology, University of Turku, Finland.
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MeSH Terms
Blotting, Northern
Cells, Cultured
Cholera Toxin / pharmacology*
Cyclic AMP / biosynthesis
DNA, Complementary
Follicle Stimulating Hormone / pharmacology
GTP-Binding Proteins / genetics,  metabolism*
Luteinizing Hormone / pharmacology
Pertussis Toxin*
RNA, Messenger / biosynthesis*
Rats, Sprague-Dawley
Testis / metabolism*
Testosterone / biosynthesis
Virulence Factors, Bordetella / pharmacology*
Reg. No./Substance:
0/DNA, Complementary; 0/RNA, Messenger; 0/Virulence Factors, Bordetella; 58-22-0/Testosterone; 60-92-4/Cyclic AMP; 9002-67-9/Luteinizing Hormone; 9002-68-0/Follicle Stimulating Hormone; 9012-63-9/Cholera Toxin; EC Toxin; EC 3.6.1.-/GTP-Binding Proteins

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