Effects of steroid hormones pretreatment on isoprenaline-induced cyclic adenosine 3′,5′-monophosphate in rat lung

Effects of steroid hormones on cyclic adenosine 3′,5′-monophosphate levels in the rat lung

“…The decrease in cAMP level in adrenalectomized rat lungs could be due to lack of the endogenous glucocorticoids and catecholamines normally produced by the adrenals. When rats were given corticosterone at doses found previously to be sufficient to cause suppression of ACTH, thymolysis, an increase in cAMP in lungs and a decrease in muscarinic receptor number in bronchial smooth muscle (Khalid, Lim, Fraillon & Funder, 1982;Lim et al 1982;Nabishah et al 1990;Nabishah, Morat, Kadir & Khalid, 1991), no significant increase in cAMP levels in the lungs of adrenalectomized rats was found at 600 pg/kg per day, but only at 1200 pg/kg per day. This implies that glucocorticoid replacement alone is insufficient to cause an increase in cAMP content when stimulated by isoprenaline and that the effects of corticosterone are enhanced by endogenous catecholamines produced by the adrenal medulla.…”

“…* P<005 compared with adrenalectomized female rats; f P<001 compared with intact male and female rats (ANOVA and LSD). DISCUSSION We have shown earlier that both DM and cortico¬ sterone at 600 pg/kg per day enhance cAMP forma¬ tion in the intact rat lung after isoprenaline stimulation (Nabishah et al 1990). In this study, adre¬ nalectomy resulted in significantly lower levels of cAMP in the lung tissue and the same dose of cortico¬ sterone (600 pg/kg) was no longer able to enhance cAMP formation as it did in the lung of the adrenal¬ ectomized rat, even though this dose was sufficient to increase cAMP in the lungs of non-adrenalectomized rats.…”

“…Five minutes after injection the rats were killed and the cAMP content of the lung tissue was measured. The dose of isoprenaline and the time-interval chosen were determined based on our previous study (Nabishah et al 1990). The lungs were removed and cAMP extraction and assay were carried out as described previously (Nabishah et al 1990).…”

“…Glucocorticoids increase cAMP levels in hepato¬ cytes (Thoresen, Gjone, Gladhaug et al 1989) and rat lungs, but mineralocorticoids have no effect (Nabishah, Merican, Morat et al 1990). Mineralo¬ corticoids and deoxycorticosterone (DOC) increase cAMP levels in kidney cortical collecting tubules but not in the outer medullary collecting tubules (Jefferies, McArdel, Bockman et al 1991).…”

Cyclic Adenosine 3′,5′‐monophosphate Content and Bronchial Smooth Muscle Contractility of Hyper‐ and Hypothyroid Lungs

“…The increase in 0-and P-adrenergic receptors in the hyperthyroid state (Ciaraldi & Marinetti 1977) may explain the adrenergic hyperactivity observed in hyperthyroidism. We have also demonstrated that glucocorticoids decrease the concentration of muscarinic receptors (Nabishah et al 1991) as well as the contractility of bronchial smooth muscle (Nabishah et al 1990b).…”