Dear DOCTOR Owen:

I read recently that I cannot feel “full” because of a deficiency of serotonin in my brain. What is serotonin? How do I know I’m deficient? Can I correct the problem?

Never Full

Dear “Never Full”:

Can you say Prozac? How about Zoloft®, Paxil®, Effexor, Luvox, Meridia®, CelexaTM, and scores of new names? These are the names of medications that are used to treat depression, and they have revolutionized the treatment and understanding of mental disorders. All of these medications “work” by inhibiting the re-uptake of serotonin—a chemical in brain cells—that makes people diagnosed with mental disorders calmer and better functioning.

The brain cells that make and use serotonin are very few in number and are located at the bottom part of the brain called the raphae nuclei. These few brain cells send “sprouts”—called dendrites (like vines)—to most of the upper parts of the brain to affect behavior and mood. As they sprout, the vines take on a life of their own, and may act and react totally differently than the parent vine, or the dendrite. At least 14 different receptors, or landing pads, for serotonin have been identified in these dendrites. When one type of receptor is turned on or activated, it causes a certain feeling or behavior. The feeding, or satiety, centers of the primitive brain—called the hypothalamus—have a large serotonin input.

Rats that are deficient in one type of receptor, 5-HT 2c, become obese and universally over-eat. It is speculated that human over-feeding is affected by poor regulation of this receptor. The weight-loss drugs, Redux (dex-fenfluramine) and Phen Fen (phenteramine and fenfluramine) affect this 5-HT 2c receptor. The antidepressants—for example, Prozac—may initially calm down this same receptor and cause satiety. But, after prolonged use, the antidepressants may have just the opposite response: cause weight gain.

Other drugs and hormones can act similarly. Hormone deficiency, which is seen after hysterectomy or menopause, can cause the serotonin receptor to malfunction, resulting in mood changes and weight gain—seen when animals are spayed or neutered. Even the type of hormone can have different effects. For example, one type of popularly used estrogen (Estradiol) can calm down the brain cell receptor, while another type (Estrone) has little or no effect. So, estrogen is not just estrogen. Several hormones may act in concert. Progesterone, DHEA, and testosterone, which are affected by aging or hysterectomy, may also affect how estrogen works on the brain cells. These effects are reviewed in Primary Psychiatry, Vol. 5, No. 10.

This new understanding is helping unravel the complex relationship between such seemingly unrelated behaviors as depression and weight gain or weight loss. Food—like a drug—acts to change serotonin levels in these brain cells, by temporarily improving mood. Permanent changes are not made, however, which leads to more depression, weight gain, and over-eating. Certain foods, like chocolate, cause more intense changes and explain, for example, why chocolate cravings are seen with hormone cycles such as pre-menstrual syndrome (PMS).

In the past, complex psychiatric explanations and therapy protocols were developed to explain these behaviors. Freud’s castration-anxiety theories were developed to explain why women experienced mood changes after hysterectomy or with menopause. This was a male explanation of a female hormonal, biochemical condition. Such theories may have reinforced a negative, narrow, “male chauvinistic” mind-set that women—the “weaker sex”—are inferior and should be “kept in their place.” Just another reason for ignorant opposition to letting women vote or work!

In the past, complex psychiatric explanations and therapy protocols were developed to explain these behaviors. Freud’s castration-anxiety theories were developed to explain why women experienced mood changes after hysterectomy or with menopause.

It is amazing to see how quickly, or how slowly, our society—even our medical society—embraces or rejects treatments that are based on perceived effect or that “fit” into the belief system of the day. Doctors are human too! These complex reasons are exactly why new treatments should be subjected to vigorous scientific scrutiny. Even with good scrutiny, prejudice creeps into the interpretations. Therefore, blinded, multiple studies are necessary to trust good research. They also explain why every “Tom, Dick, and Harry” diet treatment is embraced —for example, the latest pill herb. These methods may work by suggestion or by a chemical response, or both!

Over the last century, “quacks” and charlatans have made fortunes because society discriminates against, and causes unbearable emotional pain to, obese people. And, that very same society fails to fund research or approve a drug because it considers “gluttony” to be a moral, or character, defect, which should be overcome by “will” power—a divine attribute.

It is easy to see how simple chemical or hormonal changes can be confused with societal, cultural, or even spiritual issues.