Gonadal steroids testosterone

Androgens are masculinizing substances. The endogenous male gonadal hormone is the steroid testosterone from the interstitial Leydig cells of the testis. 

Endocrine effects Statins interfere with cholesterol synthesis and lower circulating cholesterol levels and, as such, might theoretically blunt adrenal or gonadal steroid hormone production. Small declines in total testosterone with no commensurate elevation in LH have been noted with the use of fluvastatin. Pravastatin showed inconsistent results with regard to possible effects on basal steroid hormone levels atorvastatin, lovastatin, rosuvastatin, and simvastatin did not reduce basal plasma cortisol concentration or basal plasma testosterone concentration or impair adrenal reserve. Appropriately evaluate patients who display clinical evidence of endocrine dysfunction. Exercise caution when administering HMG-CoA reductase inhibitors with drugs that affect steroid levels or activity, such as ketoconazole, spironolactone, and cimetidine. 

The step-by-step synthesis of the steroid hormones pregnenolone and progesterone from cholesterol (C27) was presented in chapter 20 (see fig 20.22). Note that pregneno-lone (C2i) and progesterone (table 20.4) (C2 ) are intermediates in the biosynthesis of all of the major adrenal steroids, including cortisol (C2i), corticosterone (C21), and aldosterone (C21). The same two compounds are intermediates in the synthesis of the gonadal steroid hormones, testosterone (C,9) and 17/3-estradiol (CI8). Because the synthesis of all these hormones follows a common pathway, a defect in the activity or amount of an enzyme along that pathway can lead to both a deficiency in the hormones beyond the affected step and an excess of the hormones, or metabolites, prior to that step. 

Human chorionic gonadotropin stimulates production of gonadal steroid hormones. The interstitial and corpus luteal cells of the female produce progesterone, and the Leydig cells of the male produce testosterone. hCG can be used to mimic a midcycle LH surge and trigger ovulation in a hypogonadotropic woman. 

There are many types of steroid hormones in the body, such as the sex/gonadal hormones testosterone and estrogen, thyroid hormones, growth hormones, and stress hormones, which serve various normal functions. One type of steroid— corticosteroids or glucocorticoids—is secreted by the adrenal glands (located just above the kidneys). These steroids, particularly synthetic versions of them, have powerful antiinflammatory actions that help to relieve pain. They are often given as an epidural injection to relieve neck or back pain that results from a compressed or pinched nerve. They can also be injected directly into a joint to relieve pain caused by inflammation in conditions such as tendonitis (inflammation of the tendons), carpal tunnel syndrome, tennis elbow, bursitis (inflammation of sac-like cavities in tendons or muscles that allow them to slide easily over bone), or other joint pain. Professional athletes, who routinely experience one or more of these conditions, are often given local steroid injections. Frequently, the steroid is combined with a local anesthetic such as lidocaine. 

An epimer of testosterone, epitestosterone (17a-hydro-xylated testosterone), is produced by the testes and excreted as such in the urine in amounts approximately equal to that of testosterone(T epiT 1 1). Epitestosterone is biologically inactive, but it is not a metabolite, and is believed to be produced only by the gonads thus, it is used as a gonadal steroid marker. In women, the ratio of T to epiT is also normally 1 1. Urinary T epiT is useful in monitoring abuse of anabolic steroids by athletes because the ratio increases when any exogenous testosterone derivative is used. 

Adrenal and gonadal steroid hormones have long been known to regulate many important brain functions (Fuxe et al., 1981 McEwen, 1991). In addition, circulating steroids like progesterone, 11-deoxycorticosterone, and testosterone can be converted to neuroactive steroids within the brain (Mellon and Griffin,... 

Both LH and FSH are referred to as gonadotropins, beoause they aot on the male and female gonads, which results in the production of the sex steroids testosterone and estradiol, respectively. In the female, FSH and LH act in concert in regulating ovarian function egg maturation, ovulation, and transformation of the ruptured follicle into the corpus luteum. In males, spermatogenesis is dependent on these two hormones. Specifically, FSH in females facilitates the maturation of ovarian folliole oells and their secretion of estradiol, whereas in males, it stimulates the maturation of sperm in the testes. In females, LH promotes ovulation, formation of the oorpus luteum, and progesterone secretion in males, it enables the secretion of testosterone from the testes. 

The influence of gonadal hormones on prepubertal animals suggests some steroidal sensitivity in adults with regard to F. elicitation. Young male sheep are induced to perform F. in response to exogenous T and to 17-p-estradiol F. in female red deer is also sensitive to T injections (Parrott, 1978 Fletcher, 1978). Sex differences can interact with the hormonal state where social conditions vary. Female cats (intact) display F. to urine marks only in the absence of males testosterone propionate induced F. in spayed females towards estrous females (Verbeme, 1976 Hart and Leedy, 1987), whereas an ovarian hormone (estradiol) failed to elicit F. to males (intact, and sexually inactive), presumably indicative of social inhibition overriding steroid facilitation. 

Occurrence in molluscs of steroidogenesis along a pathway very similar to that found in vertebrates has been claimed. Testosterone (64) - androstenedione (65) interconversion has been demonstrated in gonads of the male and female bivalve - Mytilus edulis [117] and of the gastropod Crepidula fornicata [118], by using labelled testosterone and androstenedione. Moreover, several steroids have been identified in the gonads and hepatopancreas of the opisthobranch... 

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