Brain amines and peptides--their relevance to psychiatry

Naltrexone-induced augmentation of sexual response in men

BACKGROUND

To ascertain the role of endogenous opioids in sexual response, naltrexone, an opiate receptor antagonist, was administered to men, and its effect on selected self-report measures of sexual response to masturbation was recorded.

METHODS

The data are based on results from 20 healthy, sexually active (alone or with a partner) men, aged 20-29 years, who ingested naltrexone (25 mg/day x 3) or placebo in a randomized, double-blind crossover design. There was at least a 14-day interval between drug and placebo treatment. Between 18 and 22 h after the most recent dose of drug or placebo, subjects viewed sexually explicit videos in privacy for 2 h. They were instructed to masturbate and have as many orgasms as desired. The following three different self-report measures of their responses were recorded: number of orgasms; intensity of sexual arousal, and orgasmic intensity.

RESULTS

Under the naltrexone condition, the volunteers experienced a significantly greater mean number of orgasms (3.4 +/- 0.2 SEM) than under the placebo condition (2.6 +/- 0.3). The total number of orgasms was 67 under the naltrexone condition and 51 under the placebo condition. At the first orgasm, the measure of intensity of arousal was significantly greater in the naltrexone (3.9 +/- 0.2) than placebo (3.4 +/- 0.2) condition, and the measure of orgasmic intensity was significantly greater in the naltrexone (3.7 +/- 0.2) than in the placebo (3.0 +/- 0.3) condition.

CONCLUSIONS

The present study provides evidence that endogenous opioids modulate orgasmic response and the perceived intensity of sexual arousal and orgasm in men. The findings suggest that naltrexone could be clinically useful in cases of inhibited sexual desire and erectile dysfunction.

The brain and higher mental function

Critical evaluation of biological theories of psychiatric disorder requires an understanding of current concepts of higher mental function and its related biology. Both the nature of the topic and the rapidity of advances in the field make it difficult to obtain an updated synthesis. Part I of this paper attempts to provide that by reviewing current concepts of the mind/body relationship, emotion, arousal, attention, consciousness and motivation. Part II considers those concepts in relation to recent work on the structure and function of the reticular, limbic and anterior cerebral systems. It is concluded that the model of the limbic system as subserving emotional life could now perhaps be set aside in favour of the model of a core set of chemically identified neurons in the reticular system being necessary but not sufficient to subserve higher mental function whilst also subserving other integrating functions for which no mental terminology is required. The problem of developing an eclectic theory of higher mental function that will embrace these concepts is discussed.

Low plasma beta-endorphin in post-traumatic stress disorder

We compared serum cortisol, ACTH and plasma beta-endorphin in 21 Post-Traumatic Stress Disorder patients and 20 controls. Although we found no important disturbance in diurnal rhythms, the PTSD patients had significantly higher A.M. serum cortisols compared with controls. Both A.M. and P.M. plasma beta-endorphins in PTSD patients were significantly lower compared with controls. These data suggest that plasma beta-endorphin may be a marker for PTSD and that chronic endogenous opioid depletion may play a role in the pathogenesis and perpetuation of this disorder.

The neuropsychiatry of post-traumatic stress disorder

The publication of DSM-III introduced the diagnosis Post-Traumatic Stress Disorder (PTSD), thus providing, for the first time, a framework for studying the consequences of extremely stressful events. Previously, traumatic neuroses had attracted a wide variety of labels - as wide as the experiences that produced them. Competing explanations in psychological and biological terms have characterised the approach to these disorders, and social and legal issues have added to the confusion. In recent years, psychosocial issues have tended to dominate the literature in relation to PTSD. While acknowledging the importance of such phenomenological and psychosocial approaches, this paper seeks to redress the balance by focusing on a biological perspective.

Down's syndrome: nutritional intervention

Down's Syndrome patients are known to be of short stature, prone to infections, autoimmune disease, hypothyroidism, leukaemia, heart defects and later Alzheimer's disease. They tend to have older mothers, like Alzheimer's disease patients. The latter tend to have sibs with either Down's Syndrome or lymphoma/leukaemia. Evidence, looking at 28 Down's Syndrome patients, suggests that multiple food allergies, gluten-gliadin sensitivity or intolerance are causing a coeliac disease-like picture with a malabsorption state for essential vitamins, minerals and severe autoimmune disease. It is hoped that missed gluten-gliadin sensitivity or intolerance with or without coeliac disease will be considered as a cause of abnormal oogenesis and spermatogenesis resulting in trisomy 21 and other aneuploidies. The mechanism most likely is low B1 interfering with sufficient release of cAMP for normal meiosis. Alternatively exorphins and peptides from foods may suppress prostaglandin E1 synthesis, or food sensitivities may alter toxic metal absorption mechanisms, which are thought to play a role in the development of Alzheimer's disease. Adequate vitamin/mineral supplementation, especially B1, prior to conception and in the first trimester is recommended for mothers at risk for DS, especially older mothers and a gluten free diet for those with coeliac disease or gluten-gliadin sensitivity/intolerance. Hopefully this will prevent conception of a DS child, or prevent heart defects/stigmata if one is conceived. DS children should be investigated for the above and commence a food allergy free diet with relevant supplements to meet their needs as early as maximum development.