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I M Bird

Publications and source records attributed to I M Bird.

92 records · Page 6Linked to original sources
PubMedDate not supplied

Signal transduction in rat adrenal fasciculata cells stimulated by ACTH1-39 and ACTH5-24: role of the phosphoinositide response in steroidogenesis.

Changes in the soluble inositol-containing metabolites of phosphoinositides have been measured in rat adrenal fasciculata reticularis cells stimulated by ACTH1-39 and ACTH5-24 (an analogue which is able to elicit maximal steroidogenesis in the absence of any discernible increase in cyclic AMP output). Small but significant increases in the total inositol-containing metabolites were found in response to stimulation with both ACTH analogues. For ACTH5-24 this effect on phosphoinositide (PI) metabolism occurred over the same dose range as that for the stimulation of steroidogenesis (with an ED50 of 10(-8) M ACTH5-24 for both effects). It is concluded that in the absence of cyclic AMP generation, ACTH5-24 increased the total inositol-containing metabolites in direct accordance with its steroidogenic capabilities. For ACTH1-39, the effect on PI metabolism reached a maximum with 10(-12) M ACTH1-39 and declined at higher concentrations, i.e., precisely those associated with increased cyclic AMP accumulation. These and the previous observations suggest that the cyclic AMP generated by ACTH1-39 may influence and inhibit the ACTH1-39 effect on PI metabolism. HPLC identification of the phosphoinositide metabolites of the adrenal cells showed that they include glycerophosphoinositol and glycerophosphoinositol phosphate (which would arise by sequential action of phospholipase A1 or A2 and lysophospholipase). Stimulation with ACTH1-39 elicited small but significant increases in glycerophosphoinositol levels, indicating that a phospholipase A may have been activated.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Pregnancy induces an increase in the expression of glyceraldehyde-3-phosphate dehydrogenase in uterine artery endothelial cells.

OBJECTIVE: We determined the effects of pregnancy on glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in ovine uterine and omental (systemic control) artery endothelial cells (UAEC, OAEC). We also determined in primary cultures of UAEC the effects of exposure to either exogenous nitric oxide (NO) or angiogenic growth factors (basic fibroblast growth factor [bFGF], vascular endothelial growth factor [VEGF], and epidermal growth factor [EGF]) on UAEC GAPDH expression. METHODS: We isolated UAEC to high purity from both nonpregnant (NP; n = 4) and pregnant ewes (P; 110-120 days' gestation, n = 4) by limited collagenase dispersion and immediately extracted total RNA. In additional experiments performed in vitro, ovine UAEC isolated from NP ewes and maintained in culture (n = 3) were exposed to 1) 100 mumol/L sodium nitro-prusside for 0, 6, 12, or 24 hours or 2) 10 ng/mL bFGF, VEGF, EGF, or vehicle for 24 hours. Total RNA was then immediately extracted. A partial ovine GAPDH (oGAPDH) cDNA was isolated by reverse transcriptase polymerase chain reaction (RT/PCR) and sequenced. A one-tube semiquantitative RT/PCR amplification assay was established, and GAPDH mRNA was subsequently quantified in all samples of total RNA. The PCR products were separated by size, quantified by Southern hybridization analysis, and normalized to 28S rRNA content. Expression of GAPDH protein was also measured by Western analysis of endothelium-derived protein from omental (n = 14) and uterine (n = 16) arteries from NP and P ewes. RESULTS: Pregnancy was associated with a 4.5-fold increase in GAPDH mRNA levels in UAEC, although in vitro exposure of primary cultures of UAEC from NP ewes to NO or angiogenic growth factors did not significantly change GAPDH mRNA expression. A 1.6-fold increase in GAPDH protein was detected in the uterine artery endothelium of P versus NP ewes, but no corresponding increase was found in omental artery endothelium. CONCLUSION: Pregnancy increases the expression of both GAPDH mRNA and protein in UAEC. Furthermore, the pregnancy-induced increase in GAPDH protein in the endothelium of the uterine artery appears specific, as it is not observed in the omental (systemic) artery. This induction is not, however, reproduced in vitro with exogenous NO or angiogenic growth factor treatment (up to 24 hours).

Animals↗