Gonadotropin stimuli increase adrenodoxin immunoreactivity in the mitochondria of rat ovarian cells

Adrenodoxin is a component of the electron transfer system for mitochondrial cytochrome P450 in steroidogenic cells. To elucidate whether the steroidogenic state can modulate the amount and the distribution of adrenodoxin in the mitochondria, we determined immunohistochemically the distribution of adrenodoxin and 3β-hydroxysteroid dehydrogenase (3βHSD) in ovaries of rats under hypo- and hyperfunctional states. In the ovaries of control rats, adrenodoxin was distributed in the cristae of round-shaped mitochondria of both interstitial and theca cells. In hypophysectomized rats, no adrenodoxin was found in the mitochondria of atrophied cells. Treatment of hypophysectomized rats with human chorionic gonadotropin (hCG) or Humegon restored immunostaining of adrenodoxin in the interstitial and theca cells, and rendered the vesicular cristae of C- or ring-shaped mitochondria surrounding the lipid droplets adrenodoxin-positive. The distribution of 3βHSD activity detected by enzyme histochemistry in these ovaries matched well that of adrenodoxin immunostaining. Our results indicate that immunostaining intensity of adrenodoxin in the mitochondria reflects the steroidogenic state in rat ovarian cells.