Exogeneous sex hormones

Knopp RH. Cardiovascular effects of endogenous and exogenous sex hormones over a woman s lifetime. Am J Obstet Gynecol 1988 158(6 Pt 2) 1630-43. 

TABLE 21.1 Effects of Exogenous Sex Hormones on Drug Metabolism... 

The effects of exogenous steroids can differ from those of endogenous steroids in several ways. First, the biological activity of exogenous sex hormones can be much stronger. Second, they may be metabolized differently, and third, they may induce effects that are different from those of endogenous steroids. I21 ... 

Two female sex hormones, estradiol-17 and progesterone, and one male sex hormone, testosterone, are used as growth promoters on beef cattle (Fig. 7.1). By nature, they are all endogenous products playing an important role in controlling reproductive functions in humans and animals. When applied exogenously they will enter the same metabolic pathways as the endogenously produced molecules. 

Results from randomized trials of hormone therapy in postmenopausal women cannot be extrapolated to premenopausal women with ovarian dysfunction. Women with premature ovarian failure (i.e., those younger than 40 years of age) need exogenous sex steroids to compensate for the decreased production by their ovaries. 

Oestrogenic activity is not limited to mammalian steroid hormones. In addition to endogenous oestrogens (hormones), a number of exogenous compounds present in foods of plant origin as natural components or substances that get into the food as contaminants (mould metabolites, pesticides and some other substances), also possess oestrogenic activity. These substances resemble the effect of sex hormones and induce oestrus as seen in experimental animals. 

The administration of exogenous thyroid hormone (either triiodothyronine or thyroxine) to normal male rats reduces the metabolism of hexobarbital and aminopyrine by microsomal enzymes to about 50% of control levels but increases the metabolism of these substrates by microsomes from female rats. Thus, the effect of exogenous thyroid hormone on microsomal drug metabolism is similar to that of adrenalectomy and results in a diminution in the magnitude of the sex difference. 

A number of xenobiotic substances called exogenous estrogens are thought to have adverse effects on animal and human reproductive systems by mimicking or interfering with the action of estrogens (such as those in female sex hormone) and may cause disorders of the reproductive tract and effects such as reduced sperm... 

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. 

Hopefully exogenous Oxytocin use is wisely not your thing, remember that a good sex romp bums an average of 250 calories and aids in anabolic hormone production. Who says aerobics can t be mutually beneficial ... 

Endocrine disruptors are exogenous chemicals (for example, PCBs) that enter the body and act like hormones. They can dismpt physiology, sometimes with devastating consequences. Startling evidence from animal studies shows that male fish in detergent-contaminated water express female characteristics, turtles are sex-reversed by PCBs, male frogs exposed to a common herbicide form multiple ovaries, pseudohermaphroditic offspring are produced by polar bears found in contaminated waters, and seals in contaminated water have an excess of uterine fibroids.46... 

MF may also be involved in mediating various stress responses. Hemolymph levels of the hormone rise after challenges with heat stress, hypoxia, and hypo- and hypersalinity. It is unknown how MF helps the crustacean cope with these environmental stresses. MF also acts as a sex determinant. In the cladoceran Daphnia magna, application of physiological amounts of exogenous MF to egg-maturing females resulted in all-male broods. 

Stacey N, Chojnacki A, Narayanan A, Cole T, Murphy C (2003) Hormonally derived sex pheromones in fish exogenous cues and signals from gonad to brain. Can J Physiol Pharmacol 81 329-341... 

Whether the levels of residues of sex steroids and their metabolites in edible tissues from treated animals are significantly higher than the control animals or not, the average amount of residue intake is the important point that must be considered to comprehend the impact of these hormones on human health. Also, whether the levels of the residues of the sex steroids and their metabolites have a significant impact on the consumer s health or not depends on the exogenous doses supplied in relation to the physiological levels of these hormones in the consumer [23]. 

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