The brain destruction of test animals first observed by Dr. Olney in 1969 was localized in a small group of cells in the hypothalamus called the arcuate nucleus, a tiny group of neurons that controls the release of the regulating factor for growth hormone, and may also be responsible for other pituitary hormones. Animals fed MSG not only produced less growth hormone, they also lacked the normal release pattern seen in all other mammals, including humans.250 Normally the pituitary gland secretes growth-regulating hormone in spurts, with an extra blast occurring when we fall asleep or take a nap, one reason why it is so important for children to get plenty of sleep.
Later studies found that this nucleus connected to all the other nuclei of the hypothalamus, and was therefore given a special status. We have also learned that the most important neurotransmitter in the hypothalamus is glutamate.251 As a result, high doses of glutamate given to newborn animals could damage several of the important nuclei in the hypothalamus. This was reflected in observations that many of the regulating hormones secreted by the pituitary, and controlled by the hypothalamus, were deficient in these animals.
Numerous studies using immature mice have shown that LH, FSH and prolactin (the reproductive hormones), HGH (growth hormone), ACTH (adrenal regulating hormone), and TSH (thyroid regulating hormone) were all decreased following exposure to MSG.252 These hormone deficiencies were reflected in the animals by small size, low reproductive ability, gross obesity, and low metabolism.
Other studies have confirmed these earlier findings.253 In males, one sees atrophy of the testes and lower levels of testosterone. In females, we see significantly lower LH, FSH and estradiol-17beta, the main form of estrogen hormone. In fact, the level of these hormones fell 68 percent following MSG treatment, which accounts for the decrease in the size of the ovaries and uterus.
There is some evidence that lower doses of glutamate can cause the early onset of puberty.254 Therefore, it is not surprising to learn that young girls are now undergoing early breast development and premature onset of menses in large numbers. Could this be the result of excess glutamate in the diet? We may never know since no one is looking. One problem is the widespread promotion and use of soy products. Soy is not only high in glutamate, it is also a source of phytoestrogens. The effect of this combination on the developing hypothalamus is anyone's guess.
A fairly recent series of studies found that infant animals treated with MSG have higher cortisone levels than normal mice, and following stress it takes longer for the high levels to normalize.255 This same process occurs in the elderly, and is known to endanger the brain. High levels of cortisone, especially over a long period of time, can destroy neurons in the hippocampus, a part of the brain damaged in Alzheimer's disease. Some have proposed that the elevated levels of Cortisol and slow clearance following stress eventually lead to Alzheimer's dementia. That our children may be constantly exposed to high cortisone levels from early childhood is a frightening prospect.
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