Endogenous testicular D-aspartic acid regulates gonadal aromatase activity in boar.
D-aspartic acid (D-Asp), aromatase enzyme activity and the putative D-Asp involvement on aromatase induction have been studied in the testis of mature boars. The peroxidase-antiperoxidase and the indirect immunofluorescence methods, applied to cryostat and paraffin sections, were used to evaluate D-Asp and aromatase distributions. D-Asp level was dosed by an enzymatic method performed on boar testis extracts. Biochemical aromatase activity was determined by in vitro experiments carried out on testis extracts. D-Asp immunoreactivity was found in Leydig cells, and, to a lesser extent, in germ cells. Analogously, aromatase immunoreactivity was present in Leydig cells, but absent from seminiferous tubule elements. In vitro experiments showed that the addition of D-Asp to testicular tissue acetone powder induced a significant increase of aromatase activity, as assessed by testosterone conversion to 17beta-estradiol. Enzyme Km was not affected by D-Asp (about 25 nM in control and D-Asp added tests). These findings suggest that D-Asp could be involved in the local regulation of aromatase in boar Leydig cells and intervenes in this organ's production of estrogens.
Lamanna
C
C
Department of Zoology, University of Naples 'Federico II', Naples, Italy.
Assisi
L
L
Botte
V
V
Di Fiore
M M
MM
D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D026603:D-Aspartic Acid / Q000502:physiology*; D007150:Immunohistochemistry; D007985:Leydig Cells; D008297:Male; D012044:Regression Analysis; D013552:Swine; D013737:Testis / Q000166:cytology / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
D013739:Testosterone; D026603:D-Aspartic Acid; D001141:Aromatase