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The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent) signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone.

Fluctuating asymmetry is mainly interpreted as an indicator of developmental instability, while directional asymmetry of the upper limbs is associated with handedness. The association patterns between adult androgen levels and fluctuating as well directional asymmetry patterns are still unclear. In the present study, the association between adult androgen levels, body size and directional as well as fluctuating asymmetry pattern was tested among !Kung San and Kavango males from northern Namibia. Serum concentrations of testosterone (Tser) and 5α-dihydrotestosterone (DHT) as well as salivary testosterone (Tsal) concentrations were obtained from 114 !Kung San and 136 Kavango men aged 18–40 years. Fluctuating and directional asymmetry were determined from eight paired traits. Signed and unsigned asymmetry, composite fluctuating and directional asymmetry were calculated. !Kung San males surpassed their Kavango counterparts in the directional asymmetry but also in composite directional asymmetry (CDA) significantly. Among !Kung San males, DHT correlated significantly negatively with parameters of fluctuating asymmetry as well as with parameters of directional asymmetry. Free testosterone of the saliva correlated significantly negatively with asymmetry of hand length. Among Kavango males, DHT is negatively associated with foot breadth asymmetry, but positively associated with wrist asymmetry. Although the correlations between asymmetry patterns and androgen levels are weak, it can be concluded that among !Kung San males adult androgen levels are negatively associated with a high quality phenotype.

This study evaluated the relation between testosterone changes in response to anticipatory stress and several psychological variables that contribute to the stress reaction. Salivary testosterone was determined in 76 female students under stress-free conditions and before an important examination. Individual stress reactions were highly variable in direction and extent: both significant increases and decreases were found. Thus the data did not confirm previous findings of general increases in testosterone levels under stress in women. Depending on the women's level of trait anxiety (assessed via STAI) and the general use of positive or negative cognitive coping strategies (assessed via SVF), we found significant differences in their baseline testosterone levels. Individual endocrine changes under stress were correlated with baseline testosterone levels: High testosterone concentrations at rest were more likely to drop under anticipatory stress than low concentrations. These contrasting effects can be explained by the significant interaction of trait anxiety and the sex role dimension of masculinity (assessed via BSRI) with testosterone production in females. Diese Studie befasste sich mit dem Zusammenhang zwischen den Änderungen des Testosteronspiegels in einer antizipatorischen Stresssituation und psychischen Variablen, welche die Stressreaktion beeinflussen. Bei 76 Studentinnen wurde der Speicheltestosterongehalt jeweils unter stressfreien Bedingungen und vor einer wichtigen Prüfung gemessen. Die individuellen Stressreaktionen erwiesen sich als sehr variabel in Richtung und Ausmaß: Es zeigte sich sowohl ein signifikantes Ansteigen als auch ein signifikantes Abfallen des Testosteronspiegels. Die Ergebnisse anderer Studien, in denen allgemein ein Anstieg des Testosteronwertes bei Frauen unter Stress beobachtet worden war, konnten demnach nicht bestätigt werden. Die Frauen unterschieden sich hinsichtlich ihres Basistestosteronwertes je nach dem Ausmaß ihrer Ängstlichkeit (gemessen mit dem STAI) und dem Einsatz positiver bzw. negativer Strategien der kognitiven Stressbewältigung (gemessen mit dem SVF). Die stressbedingten individuellen Änderungen des Hormonspiegels korrelierten mit dem Basistestosteronwert: War dieser hoch, fiel er unter antizipatorischem Stress eher ab als ein niedriger Basistestosteronspiegel. Diese gegenläufigen Effekte können durch die signifikante Wechselwirkung der Ängstlichkeit und der Geschlechtsrollendimension der Maskulinität (gemessen mit dem BSRI) mit der Testosteronausschüttung erklärt werden.

Genetic variations of four highly polymorphic serum proteins, TF, PI, F13B, and AHSG, were tested to distinguish one black African and one Khoisan population of southwest Africa. The results show that indeed the systems TF, PI, and AHSG are of high value for anthropological genetics: The allele frequencies for these systems enable clear identification of and distinction between black African and Khoisan populations. The F13B locus, on the other hand, reveals for both the black African and the Khoisan populations specific and unique African variants: a high frequency of F13B*2 and the lowest frequency of F13B*3 so far worldwide. The new data are compared with results for TF and PI in another black African population of Mozambique, which Rodewald et al. (1988) had studied previously. The dendrogram, based on genetic distance data D and average linkage cluster analysis, shows minimal distance between both black African populations of Namibia and Mozambique and marked distance between those and the Khoisan population of Namibia.

Genetic variations of four highly polymorphic serum proteins, TF, PI, F13B, and AHSG, were tested to distinguish one black African and one Khoisan population of southwest Africa. The results show that indeed the systems TF, PI, and AHSG are of high value for anthropological genetics: The allele frequencies for these systems enable clear identification of and distinction between black African and Khoisan populations. The F13B locus, on the other hand, reveals for both the black African and the Khoisan populations specific and unique African variants: a high frequency of F13B*2 and the lowest frequency of F13B*3 so far worldwide. The new data are compared with results for TF and PI in another black African population of Mozambique, which Rodewald et al. (1988) had studied previously. The dendrogram, based on genetic distance data D and average linkage cluster analysis, shows minimal distance between both black African populations of Namibia and Mozambique and marked distance between those and the Khoisan population of Namibia.