Harm of Prenatal Exposure to Radiation
Metabolism, Brain Size, and Lifespan in Mammals
Sodium Improves Premature Infant Development
The Brain – Estrogen’s Harm and Progesterone’s Protection
Gelatin, Glycine, and Metabolism
PUFA, Development, and Allergy Incidence
Maternal Ingestion of Tryptophan and Cancer Risk in Female Offspring
PUFA, Development, and Allergy Incidence
Role of Serotonin in Preeclampsia
Sodium Deficiency in Pre-eclampsia
Childhood conditions influence adult progesterone levels
Quotes by Ray Peat, PhD:
“In the spring, with increased day length, the brains of song-birds grow, with an increased proliferation of cells in the part of the brain involved in singing. The production of progesterone increases in most animals in the spring, and it is the main hormone responsible for the birds’ brain growth”.
“In the fetus and newborn baby, sodium promotes growth. Progesterone, sodium, and glucose are limiting factors in the growth of the baby’s brain; whey they are deficient, cells die instead of growing.”
“A bird developing inside its eggshell illustrates the way organs and the environment interact. The chicken created a very good environment for the early development of its young. When the egg is formed, it contains everything needed to produce a chicken, except for oxygen and a steady warm temperature. But before the chick’s body has finished developing, using yolk fat for energy, the glucose contained in the egg has been consumed, and at that point the chick’s brain stops growing. A researcher who knew that brain growth in other kinds of animals requires glucose, injected glucose (or glycine) into the developing eggs when the original glucose had been depleted. The supplemental glucose allowed the chick’s brain to continue growing until it hatched. These chicks had larger brains, containing more numerous cells. The same experimenters also found that progesterone increases brain size, while corticosterone decreases it. Although the egg is a very good environment for the development of chickens, these experiments showed that it isn’t the best that can be achieved. If the hen’s environment had been different, it might have been able to provide as much glucose and progesterone as the experimenters did.
Mammals were able to develop bigger brains than birds, by gestating their offspring internally, allowing a continuous supply of nutrients, such as glucose, and hormones such as progesterone. But the environment of the mother still can profoundly affect the development of the offspring, by influencing her physiology.”
“Estrogen’s brain~toxic effects have been known since the 1950s, or earlier. Text-books in the 1960s discussed experiments in which either estrogen or insulin stopped growth of the fetus’s brain, and also in the 1960s experiments were showing that progesterone fosters brain growth and intelligence. Zamenhoff’s work showed that the prenatal abundance of glucose is a central factor in brain growth. Since estrogen and insulin lower blood sugar, and progesterone and thyroid sustain it, Zamenhoff’s work showed that the level of glucose was a common factor in many of the previous experiments, though other factors, including blood volume and body temperature, are also important. The epidemiological evidence is clear that women with toxemia of pregnancy, which involves inadequate delivery of glucose to the fetus, have babies with subnormal intelligence. Among obstetricians, it used to be common knowledge (before insulin treatment became common) that diabetic women were likely to have intellectually precocious children. As the work of Shanklin, Hodin, and the Brewers shows, there is a large group of Americans with neurological damage resulting from their mothers’ treatment during pregnancy.”
In “The Biological Generality of Progesterone” (1979) I proposed that the life-long trajectory of energy production and longevity was strongly influenced by prenatal nutrition and progesterone. This idea was based on work by people such as Marion Diamond, who showed that prenatal progesterone enlarges the cortex of the brain, and that estrogen makes it smaller, and Leonell Strong, who showed that a treatment that lowered the estrogen function in a young mouse could produce cancer-free offspring for several generations. Strong’s work was very encouraging, because it showed that biological problems that had been “bred in” over many generations could be corrected by some simple metabolic treatments.
More here from Dr. Peat in a short interview excerpt.
Growth. 1979 Mar;43(1):58-61.
The effect of progesterone on brain and body growth of chick embryos.
Ahmad G, Zamenhof S.
It has been suggested that in the embryo hormonal steroids may act also as control factors for the growth of neural systems. In the present work progesterone was introduced onto the chorioallantoic membrane of the chick embryo on day 7 or days 7 and 10 of incubation. The embryo, dissected at day 10, showed significant increases in body weight and cerebral hemispheres weight. The response at day 13 was less pronounced; male embryos responded to progesterone more than the female embryos. Progesterone is a precursor to other corticosteroids, but corticosterone itself had a significant harmful effect on embryonal growth. Several possible explanations of these results have been offered. It appears that progesterone itself promotes the growth of the early embryo, but the effect depends on its age and sex.
Growth. 1979 Sep;43(3):160-6.
The effects of exogenous nutrients on growth of chick embryo brain.
Zamenhof S, Ahmad G.
The effect of an early addition of exogenous nutrients on brain growth has been investigated in chick embryo. The nutrients were introduced onto chorioallantoic membrane at day 6 or 7 of embryonal life, and the cerebral hemispheres examined at the end of neuronal proliferation for the following parameters: weight, DNA content (index of cell number) and protein content. L-Tryptophan produced significant inhibition, probably by creating amino acid imbalance and interference with the transport of other amino acids. D-Tryptophan (slower transport) was inactive. 5-Methyltryptophan produced significant inhibition, probably by causing deficiency of tryptophan utilization and of production of serotonin, which is a growth factor for early brain. Glycine stimulated brain growth, probably by conversion to glucose which is the main energy source for the embryo in this period. Brain weight and DNA were found to be significantly correlated with blood glucose level. It is concluded that, within genetic limits, early brain growth might be manipulated in both directions (inhibition or stimulation) by addition of proper nutrients during sensitive period of neuronal proliferation.
High Salivary Cortisol in Humans and Decreased Memory:
Neurobiol Aging. 2006 Nov;27(11):1705-14. Epub 2005 Nov 4.
Salivary cortisol and memory function in human aging.
Li G, Cherrier MM, Tsuang DW, Petrie EC, Colasurdo EA, Craft S, Schellenberg GD, Peskind ER, Raskind MA, Wilkinson CW.
To examine the association of salivary cortisol with cognitive changes in a 3 year longitudinal study. Previous studies have suggested that elevated glucocorticoid concentrations alter hippocampal neuronal morphology, inhibit neurogenesis, and impair cognition.
Salivary cortisol samples were collected at home by 79 cognitively intact older persons (mean age 78+/-7 years) at 08:00, 15:00 and 23:00h, and collections were repeated annually for 3 years. Cognitive function was also assessed annually.
The mean cortisol level of samples taken at three times of day and the cortisol concentration at 23:00h were significantly associated with poorer performance on tasks of declarative memory and executive function. Of 46 subjects who completed the entire 3 year study, higher initial cortisol concentration at 23:00h predicted a decline in performance of delayed paragraph recall.
These results partially confirm previous findings that high cortisol is associated with impaired declarative memory function in non-demented older persons. In addition, our data show that high salivary cortisol concentrations predict a decline in memory function over the next 3 years.