Prenatal ethanol (E) exposure has marked effects on development of the hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes. E rats show HPA hyperresponsiveness to stressors and altered reproductive function in adulthood. Importantly, prenatal ethanol differentially alters stress responsiveness in adult males and females, raising the possibility that gonadal hormones play a role in mediating ethanol effects on HPA function. To address this possibility, two studies were conducted to test the hypothesis that the differential alterations in HPA activity observed in E compared to control males are mediated, at least in part, by ethanol-induced changes in HPG effects on HPA regulation. The first study compared the effects of gonadectomy (GDX) on HPA and HPG activity in adult male offspring from prenatal E, pair-fed (PF) and ad libitum-fed control (C) dams. There were no differences among groups in basal testosterone levels under intact conditions. However, E males showed increased adrenocorticotropin but blunted testosterone and luteinizing hormone (LH) responses to restraint stress compared to PF and/or C rats, and no stress-induced elevation in arginine vasopressin (AVP) mRNA levels. GDX eliminated these differences among groups. The second study explored dose-related effects of testosterone on HPA regulation. Testosterone had less of an inhibitory effect on stress-induced CORT and LH increases in E than in PF and C males. Furthermore, testosterone had a reduced effect on central corticotropin-releasing hormone pathways, but an increased effect on central AVP pathways in E compared to PF and/or C males. Importantly, reduced androgen receptor (AR) mRNA levels, possibly reflecting downregulation of AR in key brain areas, may counteract the increased inhibitory AVP signals upstream from the paraventricular nucleus, and thus contribute to the HPA hyperresponsiveness seen in E males. Together these findings suggest that central regulation of both the HPA and HPG axes are altered by prenatal ethanol exposure. The capacity of testosterone to regulate HPA activity is altered in E males, with some effects mediated by the nutritional effects of ethanol. These changes would impair the ability to maintain homeostasis in E animals and have implications for the development of secondary disabilities in children with Fetal Alcohol Spectrum Disorder.

In dieser Studie wurde der Einfluss von anabol-androgenen Steroiden (AAS) wie Testosteron auf die Angiogenese im peripubertären Hengsthoden untersucht. Sieben von 14 Junghengsten erhielten Durateston® und wurden vier [n=3; Versuchsgruppe 1 (VG1)] bzw. zwölf [n=4; Versuchsgruppe 2 (VG2)] Wochen nach der letzten Applikation kastriert, während die übrigen sieben Tiere ohne eine Behandlung in dem gleichen Zeitraum kastriert wurden. Im Rahmen der morphometrischen Untersuchung konnte ein Anstieg der Volumendichte und der Numerischen Dichte bezüglich der Blutgefäße in der Versuchsgruppe festgestellt werden, während die Fläche der Blutgefäßanschnitte in den Kapillaren der Versuchsgruppe kleiner ist als bei den Tieren in der Kontrollgruppe. Die erhöhte Angiopietin2- und transforming growth factor alpha-Expression in der VG1 könnte möglicherweise für diese morphometrischen Be-funde verantwortlich sein. Die Blutgefäße der Versuchsgruppen zeigen, möglicherweise stimuliert durch Testoste-ron, eine höhere vascular endothelial growth factor-receptor2-Expression als die der Kontrollgruppe. Aufgrund der signifikanten Abnahme der morphometrischen Parameter von der VG1 zu der VG2 handelt es sich vermutlich um einen temporären Effekt.

The purpose of this study was to examine the effects of androstenedione supplementation on testosterone levels in older men. Healthy men (n = 11) between the ages of58 and 69 were divided into two groups: 6 taking 300 mg of androstenedione (mean ± SE, 62.33 ± 2.57) supplement and 5 taking the 300 mg cellulose placebo (mean ± SE, 60.2 ± 1.02) for a period of seven days. Subjects in both groups had been participating in the Ball State University Adult Fitness Program (BSUAFP) for at least one year, incorporating both aerobic and resistance training into their workouts. Testing measures involved the subjects performing two exercises (leg extension and leg curl) while having blood drawn prior to, during, and post-exercise for a period of 20 minutes both pre-and post-supplementation. Specific weights for the subjects were determined with a ten-repetition maximum (10-RM) lift on both exercises. It appeared that the subjects in the androstenedione group were stronger with the exercises than the subjects in the placebo group, but with no significance. Testosterone, estradiol, and androstenedione were analyzed via hormone assay pre-and post-supplementation. The analysis of the testosterone revealed a significant difference pre-(mean ± SE, 4.65 ± .51 ng/ml) to post-(mean ± SE, 6.72 ± .58 ng/ml) supplementation for the androstenedione group. Analysis of the androstenedione revealed a significant difference pre-(mean ± SE, 0.88 ± .20) to post-(mean ± SE, 7.46 ± 1.25) supplementation for the androstenedione group. The estradiol assay revealed no significant differences pre-to post-supplementation for either group. The placebo group did not demonstrate any significant differences pre-to post-supplementation for either testosterone or androstenedione. The results of this study concluded that supplementation with 300 mg. of androstenedione for a period of seven days significantly elevated blood testosterone in older men. / School of Physical Education

Prenatal ethanol (E) exposure has marked effects on development of the hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes. E rats show HPA hyperresponsiveness to stressors and altered reproductive function in adulthood. Importantly, prenatal ethanol differentially alters stress responsiveness in adult males and females, raising the possibility that gonadal hormones play a role in mediating ethanol effects on HPA function. To address this possibility, two studies were conducted to test the hypothesis that the differential alterations in HPA activity observed in E compared to control males are mediated, at least in part, by ethanol-induced changes in HPG effects on HPA regulation. The first study compared the effects of gonadectomy (GDX) on HPA and HPG activity in adult male offspring from prenatal E, pair-fed (PF) and ad libitum-fed control (C) dams. There were no differences among groups in basal testosterone levels under intact conditions. However, E males showed increased adrenocorticotropin but blunted testosterone and luteinizing hormone (LH) responses to restraint stress compared to PF and/or C rats, and no stress-induced elevation in arginine vasopressin (AVP) mRNA levels. GDX eliminated these differences among groups. The second study explored dose-related effects of testosterone on HPA regulation. Testosterone had less of an inhibitory effect on stress-induced CORT and LH increases in E than in PF and C males. Furthermore, testosterone had a reduced effect on central corticotropin-releasing hormone pathways, but an increased effect on central AVP pathways in E compared to PF and/or C males. Importantly, reduced androgen receptor (AR) mRNA levels, possibly reflecting downregulation of AR in key brain areas, may counteract the increased inhibitory AVP signals upstream from the paraventricular nucleus, and thus contribute to the HPA hyperresponsiveness seen in E males. Together these findings suggest that central regulation of both the HPA and HPG axes are altered by prenatal ethanol exposure. The capacity of testosterone to regulate HPA activity is altered in E males, with some effects mediated by the nutritional effects of ethanol. These changes would impair the ability to maintain homeostasis in E animals and have implications for the development of secondary disabilities in children with Fetal Alcohol Spectrum Disorder.

This research explores whether male risk taking emerges as a sexual display strategy in the presence of attractive women. Experiments 1 to 3 explored whether young males reported and engaged in more risk taking after viewing pictures of highly attractive females. Possible self-control mechanisms were investigated via working memory, reversal learning, and Stroop tasks. In addition, second to fourth digit ratio (2D:4D) was measured as a proxy for individual differences in testosterone. Viewing pictures of highly attractive females led to greater self-reported risk-taking. 2D:4D was found to moderate the effect on risk-taking behaviours, with increases for high, but decreases for low testosterone males. Digit ratio also moderated the effects observed on the Stroop and reversal learning tasks. Experiments 4 and 5 extended these findings to examine how power interacts with testosterone to influence risk taking and inhibitory control. As testosterone is as-sociated with the pursuit of power and status (Dabbs & Dabbs, 2000), high testoster-one individuals primed with power were expected to have little reason to disrupt the status quo and thus should be risk-avoidant. Conversely, high-testosterone individuals primed with low power were expected to use risk taking as a vehicle for pursuing po-tential gains to their status and resources. The findings from two experiments are con-sistent with these predictions. In Experiment 1, higher testosterone males (as indicated by second–fourth digit ratio) showed greater risk-taking when primed with low power. Experiment 2 replicated this effect and also showed that when primed with high power, higher testosterone males took fewer risks. The influence of power on Stroop performance was also moderated by individual differences in testosterone. Par-ticipants primed with high power showed better Stroop performance if they were lower in testosterone, whereas participants primed with low power showed better Stroop performance if they were higher in testosterone. These results suggest that greater executive control accompanies but does not underlie enhanced risk taking, caused by testosterone and power. Finally, results from a field experiment (Experiment 6) with skateboarders demon-strate that physical risk taking by young male skateboarders increases in the presence of an attractive female. This increased risk taking led to more successes but also more crash landings in front of the female observer. Mediational analyses suggest that this increase in risk taking is caused in part by elevated testosterone levels of men who performed in front of the attractive female. In addition, skateboarders’ risk taking was predicted by their performance on a reversal-learning task, reversal-learning perform-ance was disrupted by the presence of the attractive female, and the female’s presence moderated the observed relationship between risk taking and reversal learning. These results suggest that men use physical risk taking as a sexual display strategy, and they provide suggestive evidence regarding possible hormonal and neural mechanisms.

This research explores whether male risk taking emerges as a sexual display strategy in the presence of attractive women. Experiments 1 to 3 explored whether young males reported and engaged in more risk taking after viewing pictures of highly attractive females. Possible self-control mechanisms were investigated via working memory, reversal learning, and Stroop tasks. In addition, second to fourth digit ratio (2D:4D) was measured as a proxy for individual differences in testosterone. Viewing pictures of highly attractive females led to greater self-reported risk-taking. 2D:4D was found to moderate the effect on risk-taking behaviours, with increases for high, but decreases for low testosterone males. Digit ratio also moderated the effects observed on the Stroop and reversal learning tasks. Experiments 4 and 5 extended these findings to examine how power interacts with testosterone to influence risk taking and inhibitory control. As testosterone is as-sociated with the pursuit of power and status (Dabbs & Dabbs, 2000), high testoster-one individuals primed with power were expected to have little reason to disrupt the status quo and thus should be risk-avoidant. Conversely, high-testosterone individuals primed with low power were expected to use risk taking as a vehicle for pursuing po-tential gains to their status and resources. The findings from two experiments are con-sistent with these predictions. In Experiment 1, higher testosterone males (as indicated by second–fourth digit ratio) showed greater risk-taking when primed with low power. Experiment 2 replicated this effect and also showed that when primed with high power, higher testosterone males took fewer risks. The influence of power on Stroop performance was also moderated by individual differences in testosterone. Par-ticipants primed with high power showed better Stroop performance if they were lower in testosterone, whereas participants primed with low power showed better Stroop performance if they were higher in testosterone. These results suggest that greater executive control accompanies but does not underlie enhanced risk taking, caused by testosterone and power. Finally, results from a field experiment (Experiment 6) with skateboarders demon-strate that physical risk taking by young male skateboarders increases in the presence of an attractive female. This increased risk taking led to more successes but also more crash landings in front of the female observer. Mediational analyses suggest that this increase in risk taking is caused in part by elevated testosterone levels of men who performed in front of the attractive female. In addition, skateboarders’ risk taking was predicted by their performance on a reversal-learning task, reversal-learning perform-ance was disrupted by the presence of the attractive female, and the female’s presence moderated the observed relationship between risk taking and reversal learning. These results suggest that men use physical risk taking as a sexual display strategy, and they provide suggestive evidence regarding possible hormonal and neural mechanisms.

This research explores whether male risk taking emerges as a sexual display strategy in the presence of attractive women. Experiments 1 to 3 explored whether young males reported and engaged in more risk taking after viewing pictures of highly attractive females. Possible self-control mechanisms were investigated via working memory, reversal learning, and Stroop tasks. In addition, second to fourth digit ratio (2D:4D) was measured as a proxy for individual differences in testosterone. Viewing pictures of highly attractive females led to greater self-reported risk-taking. 2D:4D was found to moderate the effect on risk-taking behaviours, with increases for high, but decreases for low testosterone males. Digit ratio also moderated the effects observed on the Stroop and reversal learning tasks. Experiments 4 and 5 extended these findings to examine how power interacts with testosterone to influence risk taking and inhibitory control. As testosterone is as-sociated with the pursuit of power and status (Dabbs & Dabbs, 2000), high testoster-one individuals primed with power were expected to have little reason to disrupt the status quo and thus should be risk-avoidant. Conversely, high-testosterone individuals primed with low power were expected to use risk taking as a vehicle for pursuing po-tential gains to their status and resources. The findings from two experiments are con-sistent with these predictions. In Experiment 1, higher testosterone males (as indicated by second–fourth digit ratio) showed greater risk-taking when primed with low power. Experiment 2 replicated this effect and also showed that when primed with high power, higher testosterone males took fewer risks. The influence of power on Stroop performance was also moderated by individual differences in testosterone. Par-ticipants primed with high power showed better Stroop performance if they were lower in testosterone, whereas participants primed with low power showed better Stroop performance if they were higher in testosterone. These results suggest that greater executive control accompanies but does not underlie enhanced risk taking, caused by testosterone and power. Finally, results from a field experiment (Experiment 6) with skateboarders demon-strate that physical risk taking by young male skateboarders increases in the presence of an attractive female. This increased risk taking led to more successes but also more crash landings in front of the female observer. Mediational analyses suggest that this increase in risk taking is caused in part by elevated testosterone levels of men who performed in front of the attractive female. In addition, skateboarders’ risk taking was predicted by their performance on a reversal-learning task, reversal-learning perform-ance was disrupted by the presence of the attractive female, and the female’s presence moderated the observed relationship between risk taking and reversal learning. These results suggest that men use physical risk taking as a sexual display strategy, and they provide suggestive evidence regarding possible hormonal and neural mechanisms.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

Thesis (M.Sc. (Pharmacology)) -- Mahidol University, 1979.

Thesis (doctoral)--University of Turku, 1990. / Includes bibliographical references.