ACTH effects on aldosterone, cortisol, and other steroids

Effects of angiotensin II and adrenocorticotropic hormone on myristoylated alanine-rich C-kinase substrate phosphorylation in glomerulosa cells

Angiotensin II (AngII) is thought to stimulate aldosterone secretion from bovine adrenal glomerulosa cells in part via activation of protein kinase C (PKC), while adrenocorticotropic hormone (ACTH) functions through increases in intracellular cAMP levels and calcium influx. Rather than using invasive homogenization techniques as in previous studies, we chose to monitor PKC activity in intact glomerulosa cells in situ by measuring the phosphorylation of the endogenous PKC substrate, myristoylated alanine-rich C-kinase substrate (MARCKS). AngII enhanced MARCKS phosphorylation in a rapid, sustained manner; whereas ACTH induced a rapid and sustained inhibition of MARCKS phosphorylation. Studies using pharmacological agents to mimic various signals indicated that the AngII-induced MARCKS phosphorylation was due to PKC activation, and the ACTH-elicited decrease was mediated by increases in calcium influx rather than cAMP production. We propose that changes in the phosphorylation state of MARCKS, an actin-binding protein, may contribute to cytoskeletal rearrangements involved in steroidogenesis.

Methods in the Virtual Wetlab I: rule-based reasoning driven by nearest-neighbor lattice dynamics

We describe a discrete dynamical systems approach to exploring the hypothesis-trees associated with wetlab experiments. On-going applications of the method to experimental research using a genetically engineered mouse animal model with severe combined immune deficiency (SCID) in the area of HIV infection are outlined as an example. In conclusion, we survey how this method can be used to engineer an informational murine, called Cybermouse [Mus Cyberspacea], that can be experimented upon using current immersion technologies.

Endocrine interactions: adrenal steroids and precursors

Adult male rats (n = 48) were castrated and treated daily for 4 wk with adrenal steroids in the presence or absence of adjuvant testosterone. Dehydroepiandrosterone (DHEA), DHEA sulfate, and androstenedione (2 mg/kg body wt) were administered as cyclodextrin complexes to mimic the pharmacodynamics of the endogenous products. Although they are the substrates for testosterone synthesis in target tissues, supplements of adrenal steroids alone were unable to maintain integrity of sociosexual responses and androgen target tissues after castration. More surprising, groups administered adrenal precursor plus testosterone showed substantial suppression of the typical restoration of reproductive systems in castrates receiving androgen therapy. The adrenal steroids, however, were not functionally identical. Each steroid interacted with testosterone to leave its own distinctive "footprint" on androgen-sensitive systems. The conclusion is that the endogenous adrenal products are not simply passive precursors of testosterone. Adrenal steroids may serve as endocrine regulators of androgen bioavailability and bioactivity.

Hormonal and immunological pattern in a patient with acquired immunodeficiency syndrome related complex and Cushing's syndrome

A case of Cushing's syndrome in a 24-yr-old homosexual with an AIDS-related complex is reported. In this patient certain symptoms common to both diseases, i.e. weakness, myalgia and muscle atrophy were accentuated, whereas other symptoms pathognomic of the human immunodeficiency virus (HIV) infection, i.e. lymphoadenopathies and weight loss, were less pronounced by the high levels of circulating adrenal steroids. Ketoconazole was administered po in order to block adrenal steroidogenesis, the drug caused a remarkable fall of cortisol serum concentrations, but was unable to modify significantly the immunological pattern of the patient. Our data suggest that changes of serum adrenal steroid levels have little effect on the immune network of patients with AIDS.