Steroid Concentrations in Plasma, Whole Blood and Brain: Effects of Saline Perfusion to Remove Blood Contamination from Brain

Abstract

The brain and other organs locally synthesize steroids. Local synthesis is suggested when steroid levels are higher in tissue than in the circulation. However, measurement of both circulating and tissue steroid levels are subject to methodological considerations. For example, plasma samples are commonly used to estimate circulating steroid levels in whole blood, but steroid levels in plasma and whole blood could differ. In addition, tissue steroid measurements might be affected by blood contamination, which can be addressed experimentally by using saline perfusion to remove blood. In Study 1, we measured corticosterone and testosterone (T) levels in zebra finch (Taeniopygia guttata) plasma, whole blood, and red blood cells (RBC). We also compared corticosterone in plasma, whole blood, and RBC at baseline and after 60 min restraint stress. In Study 2, we quantified corticosterone, dehydroepiandrosterone (DHEA), T, and 17β-estradiol (E2) levels in the brains of sham-perfused or saline-perfused subjects. In Study 1, corticosterone and T concentrations were highest in plasma, significantly lower in whole blood, and lowest in RBC. In Study 2, saline perfusion unexpectedly increased corticosterone levels in the rostral telencephalon but not other regions. In contrast, saline perfusion decreased DHEA levels in caudal telencephalon and diencephalon. Saline perfusion also increased E2 levels in caudal telencephalon. In summary, when comparing local and systemic steroid levels, the inclusion of whole blood samples should prove useful. Moreover, blood contamination has little or no effect on measurement of brain steroid levels, suggesting that saline perfusion is not necessary prior to brain collection. Indeed, saline perfusion itself may elevate and lower steroid concentrations in a rapid, region-specific manner.

Extra-adrenal glucocorticoids and mineralocorticoids: evidence for local synthesis, regulation, and function

“…In the zebra finch, saline perfusion was used to remove blood contamination from the brain prior to measurement of brain steroid levels. Surprisingly, saline perfusion caused a rapid and region-specific increase in corticosterone levels in the brain, suggesting that hypoxia or ischemia could stimulate brain glucocorticoid synthesis (104).…”

Rapid Effects of an Aggressive Interaction on Dehydroepiandrosterone, Testosterone and Oestradiol Levels in the Male Song Sparrow Brain: a Seasonal Comparison

“…Solid phase extraction was conducted as described previously (22,23). Following centrifugation, 475 ll of supernatant was added to 10 ml of deionised water and then loaded onto C18 columns (500 mg, catalogue # 12113045; Agilent Bond-Elut OH; Agilent Technologies Inc., Santa Clara, CA, USA) that had been primed with 3 ml of HPLC-grade methanol and equilibrated with 10 ml of de-ionised water.…”

Extraadrenalis glükokortikoidszintézis

“…Szociális stressz hatására hasonló válaszreakciót mutattak ki [36]. Zebrapintyek fiziológiás sóoldattal történő perfúziója szintén egyes agyterületekre lokalizált kortikoszteronszint-emelkedést idézett elő, ami fokozott de novo glükokortikoidszint-emelkedésre utal agyi ischaemiával és hypoxiával járó álla-potokban [38]. Mindezen túl, neuroinflammatorikus kórképekben is felmerül az agyszövetben lokálisan képző-ÖSSZEFOGLALÓ KÖZLEMÉNY dő szteroidok jelentősége, a glükokortikoidoknak az astrocytasejtek növekedésére kifejtett gátló hatásán keresztül, elsősorban a hippocampalis régióban [39,40].…”