Uptake and metabolism of sulphated steroids by the blood–brain barrier in the adult male rat

TY - JOUR

T1 - Uptake and metabolism of sulphated steroids by the blood–brain barrier in the adult male rat

AU - Qaiser, M. Zeeshan

AU - Dolman, Diana E.M.

AU - Begley, David J.

AU - Abbott, N. Joan

AU - Cazacu-Davidescu, Mihaela

AU - Corol, Delia I.

AU - Fry, Jonathan P.

PY - 2017/9/1

Y1 - 2017/9/1

N2 - Little is known about the origin of the neuroactive steroids dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulphate (PregS) in the brain or of their subsequent metabolism. Using rat brain perfusion in situ, we have found 3H-PregS to enter more rapidly than 3H-DHEAS and both to undergo extensive (> 50%) desulphation within 0.5 min of uptake. Enzyme activity for the steroid sulphatase catalysing this deconjugation was enriched in the capillary fraction of the blood–brain barrier and its mRNA expressed in cultures of rat brain endothelial cells and astrocytes. Although permeability measurements suggested a net efflux, addition of the efflux inhibitors GF120918 and/or MK571 to the perfusate reduced rather than enhanced the uptake of 3H-DHEAS and 3H-PregS; a further reduction was seen upon the addition of unlabelled steroid sulphate, suggesting a saturable uptake transporter. Analysis of brain fractions after 0.5 min perfusion with the 3H-steroid sulphates showed no further metabolism of PregS beyond the liberation of free steroid pregnenolone. By contrast, DHEAS underwent 17-hydroxylation to form androstenediol in both the steroid sulphate and the free steroid fractions, with some additional formation of androstenedione in the latter. Our results indicate a gain of free steroid from circulating steroid sulphates as hormone precursors at the blood–brain barrier, with implications for ageing, neurogenesis, neuronal survival, learning and memory. (Figure presented.).

AB - Little is known about the origin of the neuroactive steroids dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulphate (PregS) in the brain or of their subsequent metabolism. Using rat brain perfusion in situ, we have found 3H-PregS to enter more rapidly than 3H-DHEAS and both to undergo extensive (> 50%) desulphation within 0.5 min of uptake. Enzyme activity for the steroid sulphatase catalysing this deconjugation was enriched in the capillary fraction of the blood–brain barrier and its mRNA expressed in cultures of rat brain endothelial cells and astrocytes. Although permeability measurements suggested a net efflux, addition of the efflux inhibitors GF120918 and/or MK571 to the perfusate reduced rather than enhanced the uptake of 3H-DHEAS and 3H-PregS; a further reduction was seen upon the addition of unlabelled steroid sulphate, suggesting a saturable uptake transporter. Analysis of brain fractions after 0.5 min perfusion with the 3H-steroid sulphates showed no further metabolism of PregS beyond the liberation of free steroid pregnenolone. By contrast, DHEAS underwent 17-hydroxylation to form androstenediol in both the steroid sulphate and the free steroid fractions, with some additional formation of androstenedione in the latter. Our results indicate a gain of free steroid from circulating steroid sulphates as hormone precursors at the blood–brain barrier, with implications for ageing, neurogenesis, neuronal survival, learning and memory. (Figure presented.).

KW - blood–brain barrier

KW - dehydroepiandrosterone sulphate

KW - neurosteroid

KW - pregnenolone sulphate

KW - steroid sulphatase

UR - http://www.scopus.com/inward/record.url?scp=85026733709&partnerID=8YFLogxK

U2 - 10.1111/jnc.14117

DO - 10.1111/jnc.14117

M3 - Article

C2 - 28665486

AN - SCOPUS:85026733709

SN - 0022-3042

VL - 142

SP - 672

EP - 685

JO - Journal of Neurochemistry

JF - Journal of Neurochemistry

IS - 5

ER -