Kidney extracts from spontaneously hypertensive rats (SHR) have greater dopamine 1A receptor RNA-binding activity than extracts from normotensive Wistar-Kyoto (WKY) rats.

Rat kidney extracts contain a 52 kDa protein that binds to the 3' untranslated region of the dopamine 1A (D1A) receptor mRNA at a 243 base-long cis element starting at the stop codon and ending approximately 220 bases upstream of an AUUUA-rich region. The D1A receptor RNA-binding protein (D1A-BP) is redox-sensitive; free sulfhydryl groups on the protein are required for binding. Kidney extracts from SHR have significantly more D1A-BP activity than extracts from WKY rats.

Dopamine and protein phosphatase activity in renal proximal tubules.

In the brain, dopamine, via protein kinase A (PKA) activation of dopamine- and cAMP-regulated phosphoprotein (DARPP-32), inhibits protein phosphatase 1 (PP1) activity and keeps Na(+)-K(+)-adenosinetriphosphatase (ATPase) in its phosphorylated inactive state. In the present study, we examined the relationship among dopamine, PP1, and Na(+)-K(+)-ATPase activities in renal proximal tubules. PP1 activity in proximal tubules was not decreased by dopamine (5 x 10(-9)-10(-4) M), fenoldopam (5 x 10(-6) M), or norepinephrine (5 x 10(-7) M).

Purification of a novel DBI processing product, DBI39-75, and characterization of its binding site in rat brain.

This report describes the purification and characterization from rat brain of DBI39-75, a novel, biologically active processing product of diazepam binding inhibitor (DBI). We have shown that DBI39-75 in nM concentrations stimulates pregnenolone synthesis in mitochondria of rat brain. Using cross-linking of 125I-DBI39-75 in steroidogenically active concentrations we have demonstrated for the first time that the DBI fragment has a specific high affinity binding site in rat brain.

Freeze-fracture immunocytochemical study of the expression of native and recombinant GABAA receptors.

To assess the density and distribution of native and recombinant GABAA receptors we used label-fracture and fracture-flip technologies combined with immunocytochemistry using monoclonal and polyclonal Abs directed against the extracellular domain of the GABAA receptor protein located in the freeze-fracture replicas. In cortical neurons there is a high density of GABAA receptors on both soma and dendrites with some areas were the density of receptors is higher, but there are no well defined clusters. In cerebellar granule cells most of the receptors are distributed in round clusters both in neurites and soma.

Diazepam binding inhibitor processing in the rhesus monkey brain: an immunocytochemical study.

Immunocytochemical methods were used to study the regional and cellular distribution of diazepam binding inhibitor (DBI)-, ODN (DBI 33-50)- and TTN (DBI 17-50)-like immunoreactivity (LI) in monkey brain. DBI-, ODN- and TTN-LI were found to have similar regional but different cellular distributions. The most intense staining was detected in limbic structures, especially the amygdala.