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Physiology

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Endocrinology

Question
1 out of 50
 

A male received testosterone for a long time. It may cause? (AIIMS NOV 2010)



A Azoospermia
B Increase sperm motility

C Increase spermatogenesis
D Increase gonadotropin

Ans. A Azoospermia

Testosterone,the principal hormone of the testes, is a C19 steroid with an –OH group in the 17 position. It is synthesized from cholesterol in the Leydig cells and is also formed from androstenedione secreted by the adrenal cortex.

I. ACTIONS

a. Testosterone is necessary for normal sperm development. It activates genes in Sertoli cells, which promote differentiation of spermatogonia.

b. Regulates acute HPA (Hypothalamic–pituitary–adrenal axis).

c. Maintenance of muscle trophism.

d. Testosterone regulates the thromboxane A2 receptors on megakaryocytes and platelets.

e. Libido as evinced in clitoral engorgement/penile erection frequency.

II. Regulation:

a. Castration is followed by a rise in the pituitary content and secretion of FSH and LH, and hypothalamic lesions prevent this rise.

b. Testosterone inhibits LH secretion by acting directly on the anterior pituitary and by inhibiting the secretion of GnRH from the hypothalamus.

c. As a consequence, endogenous testicular production of testosterone is reduced. Spermatogenesis is also reduced, and if administration is continued, azoospermia and infertility may result.

d. Peripheral aromatization of androgens to estrogenscan causegynecomastia.

e. Cessation of exogenous androgen treatment in normal males usually results in restoration of normal sperm levels over a 6-month period.

III. Uses

a. Infertility

b. Hypogonodism

c. lack of libido or erectile dysfunction,

d. osteoporosis,

e. bone marrow stimulation for anemia.

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