Testosterone deficiency is associated with sickle cell disease (SCD), but its underlying
mechanism is not known.We investigated the possible occurrence and mechanism of testosterone
deficiency in a mouse model of human SCD. Transgenic sickle male mice (Sickle)
exhibited decreased serum and intratesticular testosterone and increased luteinizing hormone
(LH) levels compared with wild type (WT) mice, indicating primary hypogonadism in
Sickle mice. LH-, dbcAMP-, and pregnenolone- (but not 22-hydroxycholesterol)- stimulated
testosterone production by Leydig cells isolated from the Sickle mouse testis was decreased
compared to that of WT mice, implying defective Leydig cell steroidogenesis.
There also was reduced protein expression of steroidogenic acute regulatory protein
(STAR), but not cholesterol side-chain cleavage enzyme (P450scc), in the Sickle mouse
testis. These data suggest that the capacity of P450scc to support testosterone production
may be limited by the supply of cholesterol to the mitochondria in Sickle mice. The sickle
mouse testis exhibited upregulated NADPH oxidase subunit gp91phox and increased oxidative
stress, measured as 4-hydroxy-2-nonenal, and unchanged protein expression of an
antioxidant glutathione peroxidase-1. Mice heterozygous for the human sickle globin
(Hemi) exhibited intermediate hypogonadal changes between those of WT and Sickle mice.
These results demonstrate that testosterone deficiency occurs in Sickle mice, mimicking
the human condition. The defects in the Leydig cell steroidogenic pathway in Sickle mice,
mainly due to reduced availability of cholesterol for testosterone production, may be related
to NADPH oxidase-derived oxidative stress. Our findings suggest that targeting testicular
oxidative stress or steroidogenesis mechanisms in SCD offers a potential treatment for improving
phenotypic changes associated with testosterone deficiency in this disease.