Figure 2.

The androgen-thyroid hormone (TH) crosstalk. (Top) Graphical representation of TH and 5α-dihydrotestosterone (DHT) secretion. TH is produced through the hypothalamic–pituitary–thyroid (HPT) axis and exerts its function mainly through the regulation of gene expression by binding the nuclear receptors (TRs). The TH–TR complex recognizes specific DNA-binding regions (TREs, thyroid response elements) in the promoter of target genes. Leydig cells synthesize androgens, such as testosterone, in the testis; DHT binds to ARs and the DHT–AR complex translocates into the nucleus and binds the promoter region of AR-target genes to induce gene transcription. (Bottom) Nuclear actions of TH–TRs and DHT–AR complex and the combined effects of TH and DHT. AR, androgen receptor; ARE, androgen response element; DHT, 5α-dihydrotestosterone; TH, thyroid hormone; TR, thyroid hormone receptor; TRE, thyroid hormone response element.