Study summary · research use only
Is GHRH receptor essential to GHRP-2-induced GH secretion in primary cultured rat pituitary cells?
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This study in primary cultured rat pituitary cells examined whether the GHRH receptor (GHRH-R) is required for GHRP-2-induced growth hormone (GH) secretion. Cells were treated with antisense oligonucleotides targeting GHS-R or GHRH-R mRNA, which reduced the corresponding receptor mRNA levels. Antisense GHS-R treatment reduced, but did not eliminate, GHRP-2-induced GH secretion, while GHRH-induced GH secretion was unaffected; antisense GHRH-R treatment abolished GHRH-induced GH secretion but did not affect GHRP-2-induced secretion. Treating cells with both antisense oligonucleotides together eliminated GH secretion induced by either GHRH or GHRP-2. The authors concluded that GHRH-R is required for GHRH-induced GH secretion but only partially involved in GHRP-2-induced secretion when GHS-R gene transcription is down-regulated.
Abstract
It is still controversial in rat whether the stimulation of GH secretion by GH-releasing peptides (GHRP) requires both GHRP receptor (GHRP-R) and GH-releasing hormone receptor (GHRH-R). To clarify this issue, we have postulated that inhibition of GHS-R or GHRH-R gene transcription should block GHRP-2-induced GH secretion. Rat pituitary cells were incubated for 3 days in the presence or absence of antisense 18-mer phosphorothiate oligonucleotides (ONs) complementary to the codon region of GHS-R or GHRH-R mRNAs. A significant decrease in GHRH-R and GHS-R mRNA levels was found in corresponding antisense-treated cells compared with the control cells treated with sense ON. Treatment with antisense GHS-R ON reduced (but not abolished) GHRP-2-induced GH secretion although GHRH-induced GH secretion was not altered. GHRH-stimulated GH secretion was totally abolished by the treatment with antisense GHRH-R ON, whereas GHRP-2 induced GH secretion was not affected. Treatment of cells with both GHS-R and GHRH-2 ONs however completely inhibited GHRH and GHRP-2-stimulated GH secretion. These results suggest that GHRH-R is vital for GHRH-induced GH secretion but only partially involved in GHRP-2-stimulated GH secretion under the condition of down-regulation of GHS-R gene transcription.
pepmg summarizes the peer-reviewed literature and links to every source — it sells nothing, ships nothing, and gives no medical, dosing, or human-use guidance. Don't just trust this summary: follow the citation to its source and read it yourself. Research use only.