Pharmacokinetics of the beta-carboline norharman in man

In healthy subjects, pharmacokinetics were characterised using single oral and sublingual administrations of the beta-carboline norharman. For this purpose, norharman levels in blood plasma were measured up to 90-105 min after both routes of administration. Dose proportionality of three different single oral doses of norharman (7, 65 and 110 microg/kg) administered as 0.52 and 5 mg capsules was evaluated at 8 time points. Peak levels were attained at 30 min after the oral load of norharman. Mean relative availabilities determined by the area under the curve (AUC) procedure were 14.3 and 98.0 nmol.min/l after oral dosing of 7 and 65 microg/kg, respectively. AUC values in women were 3-4 times higher than in men. Sublingual dosing of 6.5 and 13 microg/kg norharman encapsulated in 5 mg of cyclodextrins resulted in a much higher mean AUC and a more rapid absorption. Mean AUC after sublingual administration of 6.5 microg/kg was 929.8 nmol.min/kg and plasma levels were maximal 10-15 min after norharman was given. Moreover, apparently no sex difference was found using this way of application. Norharman disappeared from the plasma with half-lifes of 25-35 min, irrespective of the route of administration. Even at the highest measured norharman levels of 53 nmol/l plasma, no behavioral effects were observed. In addition, the subjects did neither report any effects nor any side-effects during the experiment. This is the first study in which the kinetics of ingested norharman have been measured in humans.

Tryptophan: a precursor for the endogenous synthesis of norharman in man

We investigated whether in healthy subjects L-tryptophan may serve as a precursor for the endogenous synthesis of the beta-carboline norharman. For this purpose subjects, smokers as well as non-smokers, received 0 or 1.2 g of an oral dose of tryptophan. Smokers started the experiment 2 h after cessation of smoking. Plasma levels of tryptophan and norharman were measured 100 and 125 min after the start of the experiment. The levels of both compounds were significantly higher in the group receiving tryptophan. Norharman concentrations in the plasma of smokers were significantly higher than in the non-smoking subjects under both experimental conditions. These results add some proof to the hypothesis that in humans tryptophan may serve as a precursor for the synthesis of norharman.

A single administration of testosterone induces cardiac accelerative responses to angry faces in healthy young women

Recently, it was demonstrated how individuals with high levels of testosterone selectively attend toward angry faces. It was argued that this suggests that high levels of testosterone are associated with an aggressive, dominating personality style. In this study, the authors used a double-blind, placebo-controlled design to examine whether exogenous testosterone would induce cardiac acceleration in response to angry faces. Participants (healthy young women) were exposed to neutral, happy, or angry faces. Administration of a single dosage of testosterone (0.5 mg) induced an accelerative cardiac response to angry faces. It is argued that this effect is due to the encouragement of dominance behavior and the inclination toward aggression. Possible mechanisms behind testosterone-driven changes in behavior are discussed with relevance to steroid-responsive networks in the limbic system that drive and control motivational and physiological aspects of social behavior.

Conscious and preconscious selective attention to social threat: different neuroendocrine response patterns

This study was designed to investigate the relationship between selective attention to social threat and neuroendocrine activity. Selective attention to social threat was measured using a supraliminal (unmasked) and a subliminal (masked) version of a pictorial emotional Stroop task, comparing color-naming latencies of neutral and angry faces. Neuroendocrine activity was assessed as (pre-task to post-task) increases in salivary cortisol and testosterone. Forty subjects were randomly assigned to the unmasked or masked version of the task. Analyses for the unmasked task revealed that post-task cortisol levels were significantly increased in subjects showing selective attention to angry faces. Results for the masked task indicated that post-task cortisol and testosterone levels were significantly increased in subjects showing preconscious selective attention to angry faces. The difference in neuroendocrine activity between tasks is suggested to depend on cortical (i.e. prefrontal) control in the unmasked task. Thus, psychological affective regulatory processes were involved in the unmasked task, whereas the neuroendocrine response patterns in the masked task indicates a biologically prepared mechanism.

Effects of food on cortisol and mood in vulnerable subjects under controllable and uncontrollable stress

The aim of this study was to investigate whether in stress-prone subjects, carbohydrate-rich, protein-poor food (CR/PP) diminished depressive mood and a cortisol response under controllable as well as uncontrollable laboratory stress. Twenty-two subjects with high stress proneness (HS) and 23 subjects with low stress proneness (LS) participated in a controllable- and uncontrollable-stress experiment during either a CR/PP or protein-rich, carbohydrate-poor (PR/CP) diet. Both controllable and uncontrollable laboratory stress significantly increased pulse rate and skin conductance in HS and LS subjects, whereas uncontrollable stress increased feelings of depression, anger, tension, and fatigue and decreased feelings of vigor. Only in HS subjects, a cortisol response and feelings of depression became lower under the CR/PP diet condition, irrespective of the controllability of the laboratory stressor, suggesting an increased ability to cope with stress. Because the CR/PP diet compared with the PR/CP diet previously has been found to cause a 42% increase in plasma tryptophan/SigmaLNAA, seen as an indirect measure of increases in brain serotonin levels, the present results suggest that an enhanced serotonin function in HS subjects may be involved.

Effects of testosterone administration on selective aspects of object-location memory in healthy young women

Previous work has indicated that object-location memory is sensitive to sex differences as well as variations in the menstrual cycle. The goal of the present study was to further examine the hormonal basis of human spatial memory by assessing the effects of a single dose of exogenous testosterone in healthy young women on three recall conditions: positional reconstruction; object-to-position-assignment; and the combined condition in which subjects both have to reconstruct the precise locations and to link the different objects to the correct places. In the latter condition, delayed recall (3 min delay) improved with testosterone. Although the effects were only small and need further substantiation, they support the idea that testosterone may have an activational effect on selective aspects of cognitive functioning.

The bovine protein alpha-lactalbumin increases the plasma ratio of tryptophan to the other large neutral amino acids, and in vulnerable subjects raises brain serotonin activity, reduces cortisol concentration, and improves mood under stress

BACKGROUND

Increased brain serotonin may improve the ability to cope with stress, whereas a decline in serotonin activity is involved in depressive mood. The uptake of the serotonin precursor, tryptophan, into the brain is dependent on nutrients that influence the cerebral availability of tryptophan via a change in the ratio of plasma tryptophan to the sum of the other large neutral amino acids (Trp-LNAA ratio). Therefore, a diet-induced increase in tryptophan availability may increase brain serotonin synthesis and improve coping and mood, particularly in stress-vulnerable subjects.

OBJECTIVE

We tested whether alpha-lactalbumin, a whey protein with a high tryptophan content, may increase the plasma Trp-LNAA ratio and reduce depressive mood and cortisol concentrations in stress-vulnerable subjects under acute stress.

DESIGN

Twenty-nine highly stress-vulnerable subjects and 29 relatively stress-invulnerable subjects participated in a double-blind, placebo-controlled study. Subjects were exposed to experimental stress after the intake of a diet enriched with either alpha-lactalbumin or sodium-caseinate. Diet-induced changes in the plasma Trp-LNAA ratio and prolactin were measured. Changes in mood, pulse rate, skin conductance, and cortisol concentrations were assessed before and after the stressor.

RESULTS

The plasma Trp-LNAA ratio was 48% higher after the alpha-lactalbumin diet than after the casein diet (P = 0.0001). In stress-vulnerable subjects this was accompanied by higher prolactin concentrations (P = 0.001), a decrease in cortisol (P = 0.036), and reduced depressive feelings (P = 0.007) under stress.

CONCLUSIONS

Consumption of a dietary protein enriched in tryptophan increased the plasma Trp-LNAA ratio and, in stress-vulnerable subjects, improved coping ability, probably through alterations in brain serotonin.

Time course of effects of testosterone administration on sexual arousal in women

BACKGROUND

The assumption that testosterone is involved in human female sexual functioning is mainly based on results of studies of women with hypogonadotropic hypogonadism. This study sought to determine the effect of testosterone administration on physiological and subjective sexual arousal in sexually functional women.

METHODS

In a double-masked, randomly assigned, placebo-controlled crossover design, we examined whether administration of a single dose of testosterone to sexually functional women increases vaginal and subjective sexual arousal when they are exposed to erotic visual stimuli. To search for a time lag in the effect of testosterone therapy, we exposed 8 healthy women to 6 erotic film excerpts depicting intercourse. The first and second excerpts were shown immediately before and 15 minutes after, respectively, intake of placebo or testosterone; the last 4 excerpts were then shown at 1(1/2)-hour intervals.

RESULTS

Sublingual intake of testosterone caused a sharp increase in plasma testosterone levels within 15 minutes; these levels declined to baseline values within 90 minutes. Three to 4(1/2) hours after reaching peak testosterone level, we found a statistically significantly increase in genital responsiveness (P = .04). Furthermore, on the day of testosterone treatment, there also was a strong and statistically significant association between the increase in genital arousal and subjective reports of "genital sensations" (P = .02) and "sexual lust" (P = .01) after 4(1/2) hours.

CONCLUSIONS

There is a time lag in the effect of sublingually administered testosterone on genital arousal in women. In addition, a consecutive increase in vaginal arousal might cause higher genital sensations and sexual lust.

Correlations among salivary testosterone, mood, and selective attention to threat in humans

An experiment was designed to investigate the relation among salivary testosterone, mood, and selective attention to threat. The participant group consisted of 32 nonclinical subjects (16 men and 16 women). Individuals completed the Profile Of Mood States (POMS) and performed a pictorial emotional Stroop task measuring selective attention to angry faces. Anticipating a time lag between testosterone (as measured in saliva) and cognitive emotional behavior, multiple time-coursed saliva samples were taken preceding the assessment of questionnaire and task for every subject. In both sexes, salivary testosterone was significantly related to mood (i.e., anger and tension) and selective attention to angry faces when saliva samples were taken 6 h before questionnaire and task assessment. Research on the relation between testosterone and human behavior might benefit by taking into account time lags between the behavioral manifestations and the continuously changing levels of testosterone.

Sex differences and menstrual cycle effects in human spatial memory

A typical test of spatial memory requires subjects to relocate a number of objects in their original, previously studied positions. It has been argued that this test includes multiple separate processing components (Postma, A., De Haan, E.H.F., 1996. Quarterly Journal of Experimental Psychology 48A (1), 178-199; Postma, A., Izendoorn, R., De Haan, E.H.F., 1998. Brain and Cognition 36, 334-345). One has to encode the precise positions occupied, assign the various objects to the correct (relative) locations, and achieve an integration of both types of spatial information. The present study examined the presence of sex differences and the role of hormonal factors for these selective components of spatial memory. A computerised, immediate (working) memory version of the test was used, comparing 23 males and 34 females on three experimental conditions: positions only, object-to-position-assignment, and the combined condition, requiring integration of the other two components. In line with previous research (Postma et al., 1998) males showed a selective advantage for fine-grained, metric positional reconstruction (i.e. positions-only). Interestingly, a within-subjects comparison in the females only revealed a menstrual cycle effect for exactly the same dimension of spatial memory. In the nonmenstrual phase, females were better than during menstruation. This clearly implies a role for sex hormones in spatial memory, even though a subsequent analysis of testosterone samples in saliva did not reveal a significant correlation with measures of spatial memory in both males and females.

Baseline salivary cortisol levels and preconscious selective attention for threat. A pilot study

This study was conducted to examine the relationship between baseline salivary cortisol (CORT) levels and selective attention for displays of angry faces. Selective attention was investigated using a pictorial emotional Stroop task, comparing colournaming-speed of angry and neutral faces. The task was assessed in supraliminal (unmasked) and subliminal (masked) conditions to 28 non-clinical subjects (14 male and 14 female). Repeated measures analysis of variance revealed a significant interaction between median split CORT levels (low vs. high) and masked face valence (angry vs. neutral). The latter effect was mainly due to significant facilitation in the high CORT subject-group; these subjects seemed to allocate their attention away from the masked angry face. A relation between baseline CORT levels and fast withdrawal behavior is suggested.

Does carbohydrate-rich, protein-poor food prevent a deterioration of mood and cognitive performance of stress-prone subjects when subjected to a stressful task?

This study investigates whether in stress-prone subjects, carbohydrate-rich, protein-poor food (CR/PP) prevents a deterioration of mood and performance under uncontrollable laboratory stress conditions. The assumption was that in stress-prone subjects there is a higher risk of serotonin deficiency in the brain and that carbohydrates may prevent a functional shortage of central serotonin during acute stress, due to their potentiating effect on brain tryptophan. Twenty-four subjects with a high stress-proneness (HS) and 24 subjects with a low stress-proneness (LS) participated in an uncontrollable stress situation under both a CR/PP and a protein-rich, carbohydrate-poor (PR/CP) diet condition. The plasma ratio of tryptophan to the other large neutral amino acids (LNAA) (ratio Tryptophan/ summation operatorLNAA) was determined as a measure indicating the dietary effect on brain tryptophan and serotonin levels. Significant increases were found in the ratio tryptophan/ summation operatorLNAA during the CR/PP diet compared with the PR/CP diet. Experimental stress had significant effects on pulse rate, skin conductance, cortisol and mood in all subjects. During the CR/PP diet only the HS subjects did not show the stress-induced rise in depression, decline in vigour and cortisol elevation that they showed after the PR/CP diet. With respect to cognitive performance, significant dietary effects were found on reaction time. It is suggested that CR/PP food in HS subjects may increase personal control, probably under the influence of higher levels of brain tryptophan and serotonin.

Discrepancies between genital responses and subjective sexual function during testosterone substitution in women with hypothalamic amenorrhea

Psychosexual dysfunction is often suggested the cause of the disturbed eating habits associated with hypothalamic secondary amenorrhea. In contrast, we explored the possibility that impaired sexual function may result from reduced levels of testosterone in amenorrheic subjects as a consequence of particular lifestyles. We studied the effects of erotic stimuli in two experiments, one comparing amenorrheic women to normal controls, the other comparing testosterone substitution to a placebo treatment. The amenorrheic women had a higher incidence of lifestyle and bodily conditions identified as risk factors for amenorrhea (i.e., weight loss before the onset of amenorrhea, low body weight, strenuous exercise, and vegetarianism), lower levels of testosterone, and impaired sexual function compared with normally menstruating women. In an experimental session in which amenorrheic women were asked to produce erotic fantasies, they demonstrated a reduced capacity for sexual fantasizing, less subjective sexual excitement, and less vaginal vasocongestion (vaginal pulse amplitude). However, when exposed to the stronger of two erotic film excerpts, the degree of vaginal response of the amenorrheic women was comparable to that of normally menstruating women. Subsequently, we showed that treatment with testosterone increased vaginal vasocongestion in the same amenorrheic women during exposure to the most potent visual stimulus but had no effect on subjective sexual experience. Testosterone substitution influenced physiological aspects of sexual function, but the psychological level remained unaffected.

Stress, serotonergic function, and mood in users of oral contraceptives

The relationship between stress and changes in insulin levels, plasma ratio of tryptophan to other large neutral amino acids (LNAAs), mood, and food intake was investigated in women taking monophasic oral contraceptives containing progestagens. Subjects experiencing high levels of stress displayed significant decreases of insulin and tryptophan to other LNAAs ratios, before and after the consumption of a standard meal during the pill-free period as compared with the period of pill use. The decline of the tryptophan to other LNAAs ratio was accompanied by worsening of mood. In a control group of subjects experiencing low levels of stress there was no relationship between insulin and tryptophan to other LNAAs ratio, nor between tryptophan to other LNAAs ratio and mood. These results suggest that the combination of stress and alterations in sex hormones may be responsible for mood changes during the pill-free period in women taking oral contraceptives.

The paradoxical nature of sexuality in anorexia nervosa

Psychosexual dysfunctioning is often put forward as an etiological factor in anorexia nervosa. In contrast, we hypothesize that anorexia nervosa patients were in general psychosexually normal before their illness, and that the problems in their sexual life arise only after the emergence of hypogonadism, as a consequence of emaciation. Our study shows that patients, before they became anorectic, were indeed rather similar to normal subjects with respect to sexual attitude. Moreover, patients reported a considerably decreased sexual interest during their anorectic period when compared with normal controls. We conclude that these results corroborate our hypotheses. In the discussion we sketch a theoretical account of the origin and course of anorexia nervosa, according to which the hormonal and associated psychosexual changes are central to its pathogenesis.