Linked Life Data

2822828

Source:http://linkedlifedata.com/resource/pubmed/id/2822828

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1987-12-15
pubmed:abstractText
The LH-induced desensitization of adenylate cyclase and LH receptor internalization in rat Leydig cells in vitro has been investigated using sub-physiological to pharmacological concentrations of LH. Leydig cells pretreated with LH for 1 h in the presence of a phosphodiesterase inhibitor showed a dose-dependent decrease in the subsequent response to a high dose of LH; this was significant with concentrations of greater than 350 fmol/l. The maximum amount of desensitization was 60%. The time-course of LH-induced desensitization of the adenylate cyclase system was investigated; with 3 nmol LH/l cyclic AMP was increased in a linear manner up to 45 min, after which time there was either no further production or (with the higher concentrations) a decreased rate of production. In order to determine whether the 'non-desensitized' adenylate cyclase activity was dependent upon LH, the LH-treated cells were acid-washed to remove residual LH; cyclic AMP production still continued, albeit at a lower rate, thus indicating that this adenylate cyclase activity did not require the further presence of LH. The effect of various concentrations of LH on the level of surface-associated LH receptors was determined in the presence of monensin to prevent receptor recycling. A dose- and time-dependent decrease was found; this was significant after 2 h with 3.5 pmol LH/l and reached a maximum of 63% of the control with 3.5 nmol/l. A dose- and time-dependent reversal of desensitization occurred if the cells pretreated with LH were washed and reincubated; with 35 pmol LH/l and after 2 h the cells were fully responsive to a challenge with fresh LH. With higher concentrations of LH in the pretreatment, partial or no recovery was found. These studies demonstrate that physiological and sub-physiological concentrations of LH induce a rapid desensitization of Leydig cell adenylate cyclase. Internalization of occupied and unoccupied LH receptors also occurred. It is proposed that these two events are linked and may, paradoxically, and because of the low numbers of LH receptors, be necessary to maintain the normal response of Leydig cells to LH in vivo.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-0795
pubmed:author
pubmed:issnType
Print
pubmed:volume
114
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
415-22
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
The dynamics of LH-induced desensitization of adenylate cyclase and LH receptor internalization in rat Leydig cells at physiological levels of LH.
pubmed:affiliation
Department of Biochemistry, Royal Free Hospital School of Medicine, University of London.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't