Parabiosis; Growth Factor 11; Stem Cells
1:24:52 – Young blood transferred to old mice and growth differentiation factor 11. We make more GDF-11 when we are young; it can make its way into the brain and muscles and stimulate stem cell proliferation. When a subject has as much age related damage as the old mouse had in this study, the only way those effects can be reversed is through some relation involving stem cells repairing and replenishing that cell population with new cells. As we age our stem cell proliferation abilities diminish.
1:26:34 – They found that they can isolate GDF-11 and inject the old mice with this isolated compound and it would have the same effect as transferring blood. At the time of the podcast, there is a study at Stanford underway which takes the plasma of young people (around age 30), which contains the GDF-11, and administering it to alzheimer’s patients. They will be checking the results immediately after and long term.
Serotonin; Impulsivity; SSRIs
1:33:47 – Impulsive behavior. There are polymorphisms in genes related to serotonin. Serotonin plays a vital role in regulating impulsivity. When you deplete a person’s serotonin levels (through, for example, limiting the amount of tryptophan that gets converted into serotonin) they become impulsive. When you take serotonin away, behavioral disinhibition occurs. Typically there are parts of the brain that inhibit signals and this inhibition is important because it keeps us from doing crazy things. Disinhibition reduces these inhibitory signals keeping us stable.
1:38:28 – Studies have shown that when you administering an acute dose of serotonin along with an SSRI (selective serotonin re-uptake inhibitor), subjects become more adverse to harming others even at the expense of saving more people.
1:40:49 – SSRIs affect pain. When on these SSRIs you feel less pain. Increasing levels of serotonin create a higher pain tolerance along with feelings of happiness and less impulsivity.
1:42:43 – Altering the serotonin system by introducing an early life stressful event. Studies involving parent and children mice have shown that when mice pups are licked, they release serotonin in the brain. This release start epigenetic feedback loops; changing the expression of the genes. They will change the amount of receptors which respond to glucocorticoids (stress hormones). Having the serotonin released at a young age increases the amount of these receptors and thus the pups generally will not release as much of that stress hormone (this is the feedback mechanism between receptor and hormone). This makes the pups less anxious as they grow up. If they don’t get licked, then serotonin is rarely released and this leads to fewer glucocorticoid receptors which means the body must release a lot of these stress hormones – essentially putting the mouse in constant state of stress.
1:46:44 – Behavioral epigenetics. Dr. Patrick brings up oxytocin and its role that it plays in creating bonds. If you take that away, the offspring grows to produce less oxytocin as a result of epigenetic changes from being deprived of the adequate amounts of oxytocin. Something similar has been observed with vasopressin, a chemical that regulates male mating behavior. Male prairie voles (a species of rodent known for being monogamous) have a higher number of receptors for vasopressin compared to other vole species known to not be monogamous. When researchers antagonize the receptors so vasopressin cannot bind to the receptor, they become polygamous. This has also been shown in non-human primates.
1:53:12 – What happens in early development in the brain. Another mouse study has shown that when young mice don’t get licked as pups, they grow to have more estrogen receptors in the brain and they get more sexually receptive. They become more promiscuous. [so I am wondering whether if this means that less estrogen will be released and if this lessened release equates to the heightened sexuality. Is this similar to the receptor/chemical balance explaining glucocorticoid and a state of stress as mentioned previously?]
1:56:15 – Rogan is interested in the possibility that the human being is a product of an equation. Patrick responds with the idea that there are things we cannot control and things we can (such as diet). She believes that diet can change the things we have come to believe are unchangeable. Getting a good diet can change the expression of our genes for the better.