Estradiol and Testosterone Secretion by Human, Simian, and Canine Testes, in Males with Hypogonadism and in Male Pseudohermaphrodites with the Feminizing Testes Syndrome

Abstract

A B S T R A C T The role of the human testis in the production of 17fi-estradiol (E2) was investigated by determining the concentration of E2 and testosterone in peripheral and spermatic vein plasma samples. Specimens were obtained from eight normal men, three men with hypogonadism, and two patients with the incomplete form of the feminizing testes syndrome. For comparison, similar studies were performed in four monkeys, 10 mongrel dogs, and 4 additional dogs who were given 1000 IU of human chorionic gonadotropin/day for 5 days. Plasma E2 was measured by radioimmunoassay utilizing sheep anti-E2 serum preceded by ether extraction and thin layer chromatographic separation of plasma steroids. Procedural blanks, which were subtracted from all reported values were 14.1 +0.74 (SEM) pg for deionized water and 13.1 ±0.66 pg for charcoaladsorbed pooled male plasma. Pooled male and pooled female control plasmas averaged 17 ±0.71 pg/ml and 95 +6.9 pg/ml, respectively; individual adult male specimens ranged between 8 and 28 with a mean of 18 ±1.4 pg/ml. In the eight normal men, the mean peripheral vein E2 concentration was 20 ±1.6 pg/ml, while the spermatic vein concentration was 50 times as great, 1049 ±57 pg/ml. All three patients with testicular abnormalities had low spermatic vein E2 concentrations (160, 280, and 416 pg/ml). Lesser E2 gradients were found across the simian (3-fold) and canine (approximately 12-fold) testes. Testicular testosterone gradients (human 110-, simian 10-, and canine 77-fold) were greater than the E2 gradients in all three species. In four dogs, HCG treatment elicited a 6-fold increase in peripheral and a 9-fold increase in spermatic vein testosterone concentrations; however, peripheral and spermatic vein E2 concentrations did not differ from control values. Spermatic vein E2 concentrations were > 4600 and 2210 pg/ml (post-HCG) in two patients with the incomplete form of the feminizing testes syndrome. Postorchiectomy, peripheral E2 and testosterone concentrations fell precipitously in both patients, confirming the major contribution of the testes, in this syndrome, to circulating E2 and testosterone. These studies provide direct evidence that the human testis secretes estradiol.

Effects of decreased estradiol-17β on the serum and anterior pituitary IGF-I system in pigs

“…Therefore, sufficient E2 may still have been synthesized in the boars to obviate the increase in serum concentrations of testosterone. The amount of E2 synthesized by the testis is variable among species (Kelch et al 1972), and aromatase enzyme activity has also been reported to vary among species (Nitta et al 1993, Inkster et al 1995. Similar results have been reported in older men where administration of anastrozole decreased serum concentrations of estradiol but failed to increase serum concentrations of testosterone (Veldhuis & Iranmanesh 2005).…”

“…Administration of 10 mg/day anastrozole was effective in preventing the increase in serum concentrations of E2 in maturing boars and decreased serum concentrations of E2 in prepubertal boars. The dosage necessary to decrease E2 synthesis in the pig may differ from that in humans due to activity or amount of the aromatase enzyme present in each species, because testicular estradiol synthesis as well as aromatase activity can vary among species (Kelch et al 1972, Nitta et al 1993, Inkster et al 1995.…”

Oestrogen deficiency in men: where are we today?

“…It is widely expressed in a number of tissues throughout the body, such as ovary (31,(35)(36)(37)(38), placenta (31,32,(38)(39)(40)(41)(42), testis (36,(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54), adipose tissue (31,(55)(56)(57)(58)(59)(60)(61)(62), muscle (55), liver (63), various sites in the brain including the hypothalamus (64)(65)(66)(67)(68), hair follicles (69), genital skin fibroblasts (70,71), fetal tissues (31,60,(72)(73)(74) (75) and in many human tumours including endometrial cancer …”

Secretion of Unconjugated Androgens and Estrogens by the Normal and Abnormal Human Testis before and after Human Chorionic Gonadotropin

“…Secretion of 17p8-estradiol (E2)' by the human testis has recently been documented and compared to the secretion of testosterone (1) Tables I and II) in 14 normal adults. Four subjects received intramuscular HCG before surgery: three 5,000 U/day for 4 days and one 5,000 U/day for 2 days.…”