Long thought to be an indispensable part of steroid hormone biosynthesis, a protein known as the translocator protein (TSPO) was unnecessary for testosterone production in male mice in a recent experiment. According to study lead author Vimal Selvaraj, PhD, of Cornell University in Ithaca, New York, his team’s finding contradicts a prevailing view held in the scientific community for nearly 25 years that TSPO is essential in steroid hormone biosynthesis.

“This discovery rectifies a huge misconception in the field,” Dr. Selvaraj commented in a statement issued by The Endocrine Society, publisher of the journal Endocrinology, in which the study findings were presented. “These findings will force scientists to reexamine conclusions drawn from numerous peer-reviewed studies of steroid hormone biosynthesis.”

According to Dr. Selvaraj, improved understanding of biosynthesis mechanisms will lead to better diagnoses and treatments for steroid hormone production disorders.

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Dr. Selvaraj and colleagues bred male mice with a TSPO deficiency in the Leydig cells. These testicular cells produce testosterone needed for the development of the testicles, the growth of accessory sex organs, reproductive behavior, and fertility.

Despite the absence of TSPO, the Leydig cells produced normal levels of testosterone, and the mice were fertile.