Testosterone functions within the brain. There are several lines of evidence for this: there are androgen receptors within the brain; testosterone is converted to both dihydrotestosterone (DHT) and estradiol by the actions of 5-α-reductase and aromatase respectively in the brain; steroid hormones promote neuronal cell growth and survival (Azad et al 2003). Testosterone enhances cerebral perfusion in hypogonadal men and that perfusion takes place specifically in Brodman areas 8 and 24, regions of the brain that are concerned with: strategic planning, higher motor action, cognitive behaviors, emotional behavior, generalized emotional reaction, wakefulness and memory (Greenlee 2000; Azad et al 2003). Studies of cognition demonstrate that older men with higher levels of free testosterone index (a surrogate measure of bioavailable testosterone) have better scores in tests of: visual memory, verbal memory, visuospatial functions and visuomotor scanning. Hypogonadal men have lower scores in tests of memory, visuospatial function, with a faster decline in visual memory (Moffat et al 2002). In a very small, short term placebo-controlled study hypogonadal men with Alzheimer’s Disease (AD) treated with testosterone demonstrated a modest improvement in a cognition assessment score in AD (Tan and Pu 2003).
Testosterone has two major effects on bones: (a) through conversion to estradiol by way of the enzyme, aromatase, testosterone inhibits osteoclastic activity and hence bone resorption; and (b) through conversion to DHT via 5-α-reductase, it stimulates osteoblastic activity and so enhances the laying down of bone (Tivesten et al 2004; Davey and Morris 2005). Hypogonadal men are at risk for the development of osteopenia or osteoporosis and hence for subsequent fracture (Fink et al 2006). About one-third of all osteoporotic hip fractures occur in men and the risk of any osteoporotic fracture in men over 50 is as high as 25 percent (Seeman 1997; Adler 2006). Although treatment with testosterone in hypogonadal men increases bone mineral density (Katznelson et al 1996), it has not yet been established that this results in a reduction in fracture rate.
The chemical synthesis of testosterone from cholesterol was achieved in August that year by Butenandt and Hanisch.[183] Only a week later, the Ciba group in Zurich, Leopold Ruzicka (1887–1976) and A. Wettstein, published their synthesis of testosterone.[184] These independent partial syntheses of testosterone from a cholesterol base earned both Butenandt and Ruzicka the joint 1939 Nobel Prize in Chemistry.[182][185] Testosterone was identified as 17β-hydroxyandrost-4-en-3-one (C19H28O2), a solid polycyclic alcohol with a hydroxyl group at the 17th carbon atom. This also made it obvious that additional modifications on the synthesized testosterone could be made, i.e., esterification and alkylation.
Scientists in Italy found that subjects who consumed roughly 3 grams of D-AA for 12 days observed a 42 percent increase in testosterone levels.[12] The researchers also noted that the D-AA group still had 22 percent more testosterone than the placebo group three days after they stopped supplementing. Conversely, a more recent article published in Nutrition Research found no increase in testosterone levels in resistance-trained males after supplementing with 3 grams of D-AA for 28 days.[13]
Testosterone is a stimulant of hematopoiesis in the bone marrow and consequently, increases the hematocrit (Shahidi 1973). Men with unexplained anemia should have their testosterone measured and if reduced, these men should be treated with testosterone. Because of the erythropoietin stimulating effect of testosterone, one of the parameters to be monitored during testosterone treatment is hematocrit since a small percent of testosterone-treated men develop polycythemia.
“This study establishes testosterone levels at which various physiological functions start to become impaired, which may help provide a rationale for determining which men should be treated with testosterone supplements,” Finkelstein says. “But the biggest surprise was that some of the symptoms routinely attributed to testosterone deficiency are actually partially or almost exclusively caused by the decline in estrogens that is an inseparable result of lower testosterone levels.”
Testosterone is the primary sex hormone in men, and it is responsible for the development of many of the physical characteristics that are considered typically male. Women also produce the hormone in much smaller amounts. Testosterone, part of a hormone class known as androgens, is produced by the testicles after stimulation by the pituitary gland, which is located near the base of the brain, and it sends signals to a male's testicles (or to a woman's ovaries) that spark feelings of sexual desire. (1)
As blood levels of testosterone increase, this feeds back to suppress the production of gonadotrophin-releasing hormone from the hypothalamus which, in turn, suppresses production of luteinising hormone by the pituitary gland. Levels of testosterone begin to fall as a result, so negative feedback decreases and the hypothalamus resumes secretion of gonadotrophin-releasing hormone. 
The biggest change I made to my diet was increasing my fat and cholesterol intake. There’s a reason why old school strong men would drink raw eggs — studies have suggested that higher fat and cholesterol consumption results in increased levels of total T; men eating low-fat diets typically have decreased testosterone levels. The emphasis on increasing fat and cholesterol consumption meant I got to eat like Ron Swanson for three months — bacon and eggs and steak was pretty much the staple of my diet.

When females have a higher baseline level of testosterone, they have higher increases in sexual arousal levels but smaller increases in testosterone, indicating a ceiling effect on testosterone levels in females. Sexual thoughts also change the level of testosterone but not level of cortisol in the female body, and hormonal contraceptives may affect the variation in testosterone response to sexual thoughts.[51]

There are many ways to naturally boost testosterone without steroid use. In fact, taking steroid hormones such as testosterone and its chemical analogs actually shuts down the body's natural production of this important muscle-building hormone. The way you train and eat can drastically affect the amount of testosterone your body produces. In addition, there are a few natural supplements that may also boost testosterone.

The participants were seen every 4 weeks. Blood was taken to measure hormone levels, and questionnaires were given to assess physical function, health status, vitality, and sexual function. Body fat and muscle measurements were also taken at the beginning and end of the 16 weeks. The study was funded in part by NIH’s National Institute on Aging (NIA) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Results appeared in the September 12, 2013, issue of the New England Journal of Medicine.
Opioid substances are in common use both licit and illicit. Opiates are potent analgesics but they are also highly addictive. They are frequently prescribed for both acute and chronic pain and when used chronically, often induce opiate dependence in the user. Pain clinics regularly use narcotic agents in many of their patients. Methadone, in particular, is regularly prescribed to opiate addicts who have entered a program aimed at reducing narcotic dosage and ultimately weaning the patient off it altogether. Most men who are on chronic high doses of an opiate become hypogonadal. This was first recognized in the 1970’s when heroin addicts were found to have suppressed levels of testosterone (Brambilla et al 1977). Also suppressed were LH and FSH pointing to a probable inhibition of GnRH release.
The brain is also affected by this sexual differentiation;[13] the enzyme aromatase converts testosterone into estradiol that is responsible for masculinization of the brain in male mice. In humans, masculinization of the fetal brain appears, by observation of gender preference in patients with congenital diseases of androgen formation or androgen receptor function, to be associated with functional androgen receptors.[95]
Important future developments will include selective androgen receptor modulators (SARMs). These drugs will be able to produce isolated effects of testosterone at androgen receptors. They are likely to become useful clinical drugs, but their initial worth may lie in facilitating research into the relative importance of testosterone’s action at the androgen receptor compared to at other sites or after conversion to other hormones. Testosterone will remain the treatment of choice for late onset hypogonadism for some time to come.
Testosterone is a sex hormone that plays important roles in the body. In men, it’s thought to regulate sex drive (libido), bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm. A small amount of circulating testosterone is converted to estradiol, a form of estrogen. As men age, they often make less testosterone, and so they produce less estradiol as well. Thus, changes often attributed to testosterone deficiency might be partly or entirely due to the accompanying decline in estradiol.
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Men can experience a range of symptoms if testosterone decreases more than it should. Low testosterone, or low T, is diagnosed when levels fall below 300 nanograms per deciliter (ng/dL). A normal range is typically 300–1000 ng/dL, according to the U.S. Food and Drug Administration. A blood test called a serum testosterone test is used to determine your level of circulating testosterone.
Osteoporosis refers to pathological loss of bone density and strength. It is an important condition due to its prevalence and association with bone fractures; most commonly of the hip, vertebra and forearm. Men are relatively protected from the development of osteoporosis by a higher peak bone mass compared with women (Campion and Maricic 2003). Furthermore, women lose bone at an accelerated rate immediately following the menopause. Nevertheless, men start to lose bone mass during early adult life and experience an increase in the rate of bone loss with age (Scopacasa et al 2002). Women of a given age have a higher prevalence of osteoporosis in comparison to men but the prevalence increases with age in both sexes. As a result, men have a lower incidence of osteoporotic fractures than women of a given age but the gap between the sexes narrows with advancing age (Chang et al 2004) and there is evidence that hip fractures in men are associated with greater mortality than in women (Campion and Maricic 2003).
For this reason I recommend doing your own research on this supplement before taking it. 5g of ground up dried powder is what was used in the studies. I recommend taking 1-2 capsules of the concentrated form from Paradise Herbs. Alternatively, the Aggressive Strength Test Booster also has MP in its formula so you may prefer to use that blend instead. 
This evidence, together with the beneficial effects of testosterone replacement on central obesity and diabetes, raises the question whether testosterone treatment could be beneficial in preventing or treating atherosclerosis. No trial of sufficient size or duration has investigated the effect of testosterone replacement in primary or secondary prevention cardiovascular disease. The absence of such data leads us to examine the relationship of testosterone to other cardiovascular risk factors, such as adverse lipid parameters, blood pressure, endothelial dysfunction, coagulation factors, inflammatory markers and cytokines. This analysis can supply evidence of the likely effects of testosterone on overall cardiovascular risk. This has limitations, however, including the potential for diverging effects of testosterone on the various factors involved and the resultant impossibility of accurately predicting the relative impact of such changes.
Testosterone levels generally peak during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30 or 40. It is important to determine in older men if a low testosterone level is simply due to the decline of normal aging or if it is due to a disease (hypogonadism).