The hypothalamus-pituitary-gonadal axis (HPG axis) plays an essential role in regulating early development, adolescence, and sustaining the adult reproductive functions. Two of the more commonly used markers are Ki67 and doublecortin (DCX), which are expressed in proliferating cells and early developing neurons, respectively 28,29,30,31. BrdU-labeling allows cells to be precisely birth dated based on the timing of injections and brain tissue collection, and co-labeling with neuronal and glial markers allows quantification of cellular differentiation. A few supplements can help sustain healthy testosterone levels, but most supplements marketed as testosterone boosters don’t work, though some can make you believe they do by boosting your libido. Additionally, exposure to sunlight while hiking ensures a healthy dose of vitamin D, which plays a crucial role in supporting testosterone levels. Vitamin D is essential for testosterone production, so consider vitamin D supplements to maintain optimal levels. Chronic stress can lead to increased cortisol production, which can have a negative impact on testosterone levels. If you’re interested in trying supplements to boost your testosterone, always clear it with a doctor or other healthcare professional first, especially if you’re taking hormone replacement therapy or one or more medications. Adding Thorne Zinc Picolinate to your daily routine can be a quick and convenient way to boost your zinc intake to support healthy testosterone levels. Fifteen and 30 consecutive days of estradiol injections had no effect on neurogenesis in male rats 43,88, suggesting a species difference or a differential effect of prolonged exposure to estradiol compared an acute (5 day) burst of estradiol during the cell migration period. In summary, a relatively high physiological dose of testosterone given over a prolonged period (approximately 30 days) enhances neurogenesis within the dentate gyrus of male rodents by increasing cell survival. As one relevant example, transgenic mice (Sema7A knockout) that have reduced GnRH release from the hypothalamus, and therefore reduced testosterone levels from birth, showed no preference for female odors over male odors in adulthood (i.e., they lacked typical male sex preferences) . A study published in the journal Reproductive Biology and Endocrinology tracked testosterone levels in men from 2006 to 2019. Recent research shows that testosterone levels have been dropping for decades, and it’s not just due to aging or obesity. Load up that sled and push your way to higher testosterone levels. Regular physical activity, especially exercises that engage multiple muscle groups, can help promote the natural production of testosterone, a hormone essential for energy, strength, and overall well-being. However, blocking DHT production using finasteride caused a decrease in both cell proliferation and DCX-expressing cells within the hippocampus of male mice . Paralleling the findings for testosterone replacement, DHT injections had no effect on levels of cell proliferation in the dentate gyrus of rats, mice, or voles 97,100,105,106. A supra-physiological dose of testosterone given to male mice during early cellular development (0–2 days after birth) had no effect on subsequent survival of 28-day-old cells . It is unclear whether 24 (or more) consecutive days of testosterone exposure is needed to enhance adult neurogenesis, or if acute bursts of testosterone during specific stages of neuronal development would have the same neurogenesis-enhancing effect. Thus, current evidence indicates that the later stages of neural development are sensitive to the neurogenesis-enhancing effects testosterone, while the effects of testosterone on cell proliferation and early stages of neurogenesis seem to be minimal. Interestingly, shorter periods (15–21 days) of testosterone replacement did not increase neurogenesis relative to castrated control rats 93,94,101.
