Adolescent anabolic/androgenic steroids: Aggression and anxiety during exposure predict behavioral responding during withdrawal in Syrian hamsters (Mesocricetus auratus)

In the U.S. and worldwide anabolic/androgenic steroid use remains high in the adolescent population. This is concerning given that anabolic/androgenic steroid use is associated with a higher incidence of aggressive behavior during exposure and anxiety during withdrawal. This study uses pubertal Syrian hamsters (Mesocricetus auratus) to investigate the hypothesis that an inverse behavioral relationship exists between anabolic/androgenic steroid-induced aggression and anxiety across adolescent exposure and withdrawal. In the first experiment, we examined aggression and anxiety during adolescent anabolic/androgenic steroid exposure and withdrawal. Adolescent anabolic/androgenic steroid administration produced significant increases in aggression and decreases in anxiety during the exposure period followed by significant decreases in aggression and increases in anxiety during anabolic/androgenic steroid withdrawal. In a second experiment, anabolic/androgenic steroid exposed animals were separated into groups based on their aggressive response during the exposure period and then tested for anxiety during exposure and then for both aggression and anxiety during withdrawal. Data were analyzed using a within-subjects repeated measures predictive analysis. Linear regression analysis revealed that the difference in aggressive responding between the anabolic/androgenic steroid exposure and withdrawal periods was a significant predictor of differences in anxiety for both days of testing. Moreover, the combined data suggest that the decrease in aggressive behavior from exposure to withdrawal predicts an increase in anxiety-like responding within these same animals during this time span. Together these findings indicate that early anabolic/androgenic steroid exposure has potent aggression- and anxiety-eliciting effects and that these behavioral changes occur alongside a predictive relationship that exists between these two behaviors over time.     

Effect of anabolic steroid nandrolone decanoate on the properties of certain enzymes in the heart, liver, and muscle of rats, and their effect on rats' cardiac electrophysiology.

Nandrolone decanoate (ND) is an anabolic steroid, modified to enhance anabolic rather than androgenic actions. The physiological effects of ND treatment are often used in various aspects of medical practice. In this investigation we have tried to establish whether a single, high dose of ND (20 mg/kg) would cause any anabolic effects. Moreover, we have attempted to correlate the eventual effects with changes in the activity and kinetic properties of anabolic- and bioenergetic-involved enzymes in different tissues of rats, along with the rats' ECG parameters. The body and liver weights of the rats were unchanged, but heart weight had increased 10 days after ND injection. Electrocardiographic data showed a small prolongation of the QRS complex 3, 6, and 10 days after ND treatment. It was established that ND causes activation of glucose-6-phosphate and 6-phosphogluconate dehydrogenases, malic enzyme, and NADP-linked isocitrate dehydrogenase in rat hearts. Moreover, 6-phosphogluconate dehydrogenase from the hearts of ND-treated rats showed higher affinity to its substrate, in comparison with control. Activation of transketolase by ND in the liver was accompanied by inhibition of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. We observed an increase of glucose 6-phosphate dehydrogenase and NAD-linked malate dehydrogenase in the muscle of ND treated rats. It may be concluded that ND in a single high dose exhibits cardiotrophic action, especially towards the increase of heart dehydrogenases activity which generates NADPH and supplies ribose phosphate for the biosynthesis of nucleotides and nucleic acids. On the other hand, ND may cause activation of ATP synthesis in muscle by enhanced malate-aspartate shuttle action.     

The impact of nandrolone decanoate and growth hormone on biosynthesis of steroids in rats

Growth hormone (GH) and anabolic androgenic steroids (AAS) are commonly used in sports communities. Several studies have suggested an association between GH and AAS. We have investigated the impact of GH in rats treated with nandrolone decanoate (ND). Male Wistar rats received ND (15 mg/kg) every third day during three weeks and were subsequently treated with recombinant human GH (1.0 IU/kg) for ten consecutive days. Plasma samples were collected and peripheral organs (i.e. heart, liver, testis and thymus) were dissected and weighed. Concentration of thirteen endogenous steroids was measured in the rat plasma samples using high specificity LC–MS/MS methods. Seven steroids were detected and quantified, and concentrations of estrone, testosterone, and androstenedione were significantly different among the groups, while concentrations of pregnenolone, DHEA, 17-hydroxyprogesterone and corticosterone were not altered. Administration of rhGH alone altered the plasma steroid distribution, and the results demonstrated significantly increased concentrations of plasma estrone as well as decreased concentrations of testosterone and androstenedione in the ND-treated rats. Administration of rhGH to ND-pretreated rats did not reverse the alteration of the steroid distribution induced by ND. Administration of ND decreased the weight of the thymus, and addition of rhGH did not reverse this reduction. However, rhGH administration induced an enlargement of thymus. Taken together, the plasma steroid profile differed in the four groups, i.e. control, AAS, rhGH and the combination of AAS and rhGH treatment.     

Effects of previous experience on the agonistic behaviour of male crickets, Gryllus bimaculatus

Male solitary animals frequently enter aggressive interactions with conspecific individuals to protect their territory or to gain access to females. After an agonistic encounter, the loser (subordinate individual) changes its behaviour from aggression to avoidance. We investigated agonistic interactions between pairs of male crickets to understand how dominance is established and maintained. Two na?ve males readily entered into agonistic interactions. Fights escalated in a stereotyped manner and were concluded with the establishment of dominance. If individuals were isolated after the first encounter and placed together 15 minutes later, subordinate crickets tended to avoid any further contact with the former dominant opponent. Moreover, subordinate males also avoided unfamiliar dominant and na?ve opponents. They displayed aggressive behaviour only towards unfamiliar subordinate opponents. This suggests that the subordinate male change their behaviour depending on the dominance status of the opponent. Dominant crickets, in contrast, displayed aggressive behaviour towards familiar as well as unfamiliar opponents. If the interval between the first and second encounter was longer than 30 minutes, the former subordinate male showed aggressive behaviour again. However, if the subordinate cricket was paired with the same opponent three consecutive times within 45 minutes, it avoided the former dominant opponent for up to 6 hours following the third encounter. Our results suggest that the maintenance of dominance in male crickets depends largely on the behavioural change of subordinate individuals. Possible mechanisms to maintain dominance are discussed.     

Mating Resets Male Cricket Aggression

An animal’s motivational state can significantly impact its behavior. We examined the effects of mating on the aggression of male Acheta domesticus crickets. Pairs of males were allowed to establish dominance and subordinance and were then physically separated. Subordinate males were then allowed to either copulate with a female or to have chemo-tactile contact with, but to not copulate with, a female. Less than 15 min after separation, all male pairs engaged in a second agonistic encounter. Subordinate males that copulated with females were significantly more aggressive toward their dominant partners than un-mated subordinate males. Many mated subordinates became dominant. Allowing a subordinate male to contact, but not copulate with, a female had a similar effect, suggesting that chemo-tactile cues from the female are sufficient to elicit this change in aggression.     

Effects of Nandrolone in the Counteraction of Skeletal Muscle Atrophy in a Mouse Model of Muscle Disuse: Molecular Biology and Functional Evaluation

Muscle disuse produces severe atrophy and a slow-to-fast phenotype transition in the postural Soleus (Sol) muscle of rodents. Antioxidants, amino-acids and growth factors were ineffective to ameliorate muscle atrophy. Here we evaluate the effects of nandrolone (ND), an anabolic steroid, on mouse skeletal muscle atrophy induced by hindlimb unloading (HU). Mice were pre-treated for 2-weeks before HU and during the 2-weeks of HU. Muscle weight and total protein content were reduced in HU mice and a restoration of these parameters was found in ND-treated HU mice. The analysis of gene expression by real-time PCR demonstrates an increase of MuRF-1 during HU but minor involvement of other catabolic pathways. However, ND did not affect MuRF-1 expression. The evaluation of anabolic pathways showed no change in mTOR and eIF2-kinase mRNA expression, but the protein expression of the eukaryotic initiation factor eIF2 was reduced during HU and restored by ND. Moreover we found an involvement of regenerative pathways, since the increase of MyoD observed after HU suggests the promotion of myogenic stem cell differentiation in response to atrophy. At the same time, Notch-1 expression was down-regulated. Interestingly, the ND treatment prevented changes in MyoD and Notch-1 expression. On the contrary, there was no evidence for an effect of ND on the change of muscle phenotype induced by HU, since no effect of treatment was observed on the resting gCl, restCa and contractile properties in Sol muscle. Accordingly, PGC1α and myosin heavy chain expression, indexes of the phenotype transition, were not restored in ND-treated HU mice. We hypothesize that ND is unable to directly affect the phenotype transition when the specialized motor unit firing pattern of stimulation is lacking. Nevertheless, through stimulation of protein synthesis, ND preserves protein content and muscle weight, which may result advantageous to the affected skeletal muscle for functional recovery.     

Aggression in male rats receiving anabolic androgenic steroids: effects of social and environmental provocation.

This study examined the effects of anabolic androgenic steroids (AAS) on aggression under different social and environmental conditions. Three AAS were tested in gonadally intact male rats: testosterone propionate (TP), nandrolone (ND), and stanozolol (ST). Doses of 5 mg/kg were given 5 times/week, with gonadally intact controls receiving vehicle only (propylene glycol). Animals received six weekly tests under each condition in a counterbalanced order. Results show that the three AAS differed in their ability to elicit aggression. Males receiving TP were more aggressive than controls, ND males were similar to controls, and ST males were less aggressive than controls. In the social and environmental provocation tests TP-treated males were more aggressive than other groups, but were able to discriminate between intact and castrated opponents and between their home cage and a neutral cage. In the environmental provocation test, TP males were also more aggressive against opponents when tested in the opponent's home cage. It is suggested that chronic exposure to high levels of TP does not eliminate the ability to discriminate between social or environmental cues, as might be expected if it induces a " 'roid rage." However, TP does increase the likelihood that the animal will respond with aggression/dominance in a provoking situation. All three AAS variably affected serum testosterone and LH levels, as well as testes, seminal vesicle, and prostate weights. No effect on body weight was observed.     

<Emphasis Type="Italic">Polistes japonicus</Emphasis> (Hymenoptera,Vespidae) queens monopolize ovipositing but are not the most active aggressor in dominant-subordinate interactions

In order to elucidate the dominant–subordinate relationship between the foundress and workers, five colonies of the paper wasp Polistes japonicus were observed in a netted and covered cage located outdoors. The number of workers in each colony ranged from four to eight. Workers were divided into first and second broods. Abdominal wagging and ovipositing were performed almost exclusively by the foundress throughout colony development. However, an analysis of aggressive encounters indicated that although the foundress hardly received dominance behaviors (aggression) from workers, it lacked either partially or completely the following characteristics of the queen that are usually seen in paper-wasp colonies with independent-founding queens (except in one colony that produced no second brood): the queen being socially dominant over any worker (the queen had more wins than losses in one-on-one dominance contests with any worker), exhibiting the highest frequency of dominance behaviors, and directing dominance behaviors primarily toward the socially most-dominant worker. In particular, during the mixed-brood period (when all first- and second-brood workers were present on the nest) the foundress hardly exhibited dominance behaviors toward socially dominant workers (mainly second brood) but frequently directed dominance behaviors toward socially subordinate workers (mainly first brood). The foundress disappeared in two colonies before the reproductives emerged; in these colonies the socially most-dominant worker inherited the colony and laid many eggs. The frequency of abdominal wagging by these two foundresses decreased during colony development, while it did not in the other colonies. This suggests that abdominal wagging provides information about the vigor of the performer. The superseder was socially dominant over all other workers, but spent little time wagging its abdomen and allowed some workers to lay eggs.     

Social dominance regulates androgen and estrogen receptor gene expression

In Astatotilapia burtoni, dominant males have higher levels of sex steroid hormones than subordinate males. Because of the complex regulatory interactions between steroid hormones and receptors, we asked whether dominance is also associated with variation in sex steroid receptor gene expression. Using quantitative PCR, we compared the expression of specific subtypes of androgen (AR) and estrogen (ER) receptor genes between dominant and subordinated males in 3 divisions of the brain, the pituitary, and the testes. We measured mRNA levels of AR-alpha, AR-beta, ER-alpha, ER-betaa, and ER-betab, gonadotropin-releasing hormone 1 (GnRH1), and GnRH receptor 1 (GnRH-R1) relative to 18S rRNA. In the anterior part of the brain, we found that dominant males had higher mRNA expression of AR-alpha, AR-beta, ER-betaa, and ER-betab, but not ER-alpha, compared to subordinate males. This effect of dominance was reflected in a positive correlation between testes size and AR-alpha, AR-beta, ER-betaa, and ER-betab in the anterior brain. In addition, mRNA levels of all ARs and ERs in the anterior brain were positively correlated with mRNA level of GnRH1. In the middle and posterior portions of the brain, as well as the testes, steroid receptor mRNA levels were similar among dominants and subordinates. In the pituitary, ER-alpha mRNA level was positively correlated with testes size and AR-alpha mRNA was positively correlated with GnRH-R1 mRNA level. These data suggest that dominant male brains could be more sensitive to sex steroids, which may contribute to the increased complexity of the behavioral repertoires of dominant males.     

Social context influences aggressive and courtship behavior in a cichlid fish

Social interactions require knowledge of the environment and status of others, which can be acquired indirectly by observing the behavior of others. When being observed, animals can also alter their signals based on who is watching. Here we observed how male cichlid fish (Astatotilapia burtoni) behave when being watched in two different contexts. In the first, we show that aggressive and courtship behaviors displayed by subordinate males depends critically on whether dominant males can see them, and in the second, we manipulated who was watching aggressive interactions and showed that dominant males will change their behavior depending on audience composition. In both cases, when a more dominant individual is out of view and the audience consists of more subordinate individuals, those males signal key social information to females by displaying courtship and dominant behaviors. In contrast, when a dominant male is present, males cease both aggression and courtship. These data suggest that males are keenly aware of their social environment and modulate their aggressive and courtship behaviors strategically for reproductive and social advantage.     

Aggression within social groups of rhesus monkeys (Macaca mulatta): Effect of contact between groups

Social contact between two groups of rhesus monkeys within tunnel-connected enclosures affected the frequency of aggressive interaction within each group. Contact decreased aggression within the subordinate group but increased it within the dominant group. When the dominance relationship between the two groups was experimentally reversed the effect of contact on intragroup aggression correspondingly reversed.     

Influences of microhabitat use and foraging mode similarities on intra- and interspecific aggressive interactions in a size-structured stream fish assemblage

Aggressive interactions, foraging behaviour and microhabitat use were observed among four sympatric stream fishes inhabiting the water column: ayu (Plecoglossus altivelis), white-spotted charr (Salvelinus leucomaenis), masu salmon (Oncorhynchus masou) and Japanese dace (Tribolodon hakonensis), each species being categorised into five body-size classes (species-size groups; SSG's). Aggressive interactions were observed between most pairs of SSG's, an almost linear dominance order being apparent throughout the three-month study period. Ayu were relatively subordinate in June, but became the second most dominant in July and the most dominant in August, as a consequence of a reversal in dominance order with salmon. In contrast, smaller-sized dace, which continually suffered from intra- and interspecific aggression, occupied the most subordinate ranks throughout the study period. Intensive aggression was observed among various SSG's, exhibiting same microhabitat propensity throughout the three months. The direction and frequency of aggressive interactions varied month by month due to a reversal in dominance order between ayu and masu salmon, and/or changes in density, body size and resource use of the component members. Opponent selectivity was higher within SSG's, where resource use was assumed to be highly overlapping, rather than among SSG's throughout the study period. Correlation analysis indicated that opponent selectivity in aggressive interactions among SSG's was positively correlated with similarity in microhabitat selectivity in June, but not in other months or with that in foraging habits, suggesting that intensive aggressive behaviour reflected overlapping habitat use among assemblage members during a certain period.     

Effect of early androgen treatment on subsequent social behavior in heifers

Two groups of four heifers received daily injections of 0.30 mg/kg of testosterone propionate in oil for 100 days, between 3 and 6 months of age. Two other groups of four heifers of the same age received only oil and served as controls. Three to five months after the end of treatment, a series of experiments was designed to compare dominance ability, aggressiveness, and reactions associated with fear, between treated and control animals. Dominance ability, when faced with animals of the same age and social experience, is higher for treated animals than controls, 85% of them being dominant. Treated animals established dominance relationships between themselves more slowly than did control animals or mixed pairs. In all experiments treated animals fought more often than controls. Those which became subordinate fought more than those which became dominant. When subordinate, treated animals withdrew less often than control animals and frequently did not react to aggression. When dominant, treated animals were never more, and sometimes less, aggressive than controls. It is proposed that changes in social structure of organized groups and the capacity to become dominant at first encounter are due to a reduction of fear of other animals induced by androgens. The acquisition of social rank in cattle may be principally due to differences in fear or “emotionality” rather than in aggressiveness.     

Changes in the speed of ants as a result of aggressive interactions

Subordinate ant species utilize different tactics to reduce competition with the stronger, larger and more aggressive individuals of a dominant species. In our experimental study, we assessed the behavioral response of individual workers of 4 subordinate ant species during their co‐occurrence with workers of a single dominant species. Contrary to most classical experiments focused on aggressive interactions, we assessed workers’ speed as a crucial factor in the outcome of co‐occurrence. Generally, there was a large intraspecific variation in the speed of the studied species—each had slow and fast individuals. Workers of all studied species moved faster just after interaction, suggesting that contact between 2 hostile workers is a stressful stimulus, generating a behavioral reaction of increasing speed. Also, the number of aggressive contacts experienced by a given individual positively affected its speed. Moreover, workers which were fast when exploring territory were also fast after interspecific interactions. The duration of aggression was significantly reduced by the speed and body size of a subordinate species worker—the more quickly a worker reacted and bigger it was, the shorter was the time of cumulative aggression. To our knowledge, this is the first study of this type to be conducted on ants and we conclude that speed is an overlooked and important characteristic of species and also individuals, therefore it should be considered as a driver of patterns of co‐occurrence in ant assemblages.     

Social status modifies estradiol activation of sociosexual behavior in female rhesus monkeys

Estrogen (E2) has activational effects on sexual motivation and mitigating effects on anxiety-like behaviors that can be attenuated with chronic exposure to psychosocial stress. Some studies suggest that this attenuation can be overcome by higher doses of E2, while others show that chronic psychosocial stress may alter the mechanisms of E2 function, thus reducing any positive benefit from higher doses of E2. To determine the interaction between psychosocial stress and E2 dose on behavior, we examined the scope of attenuation across a suite of socioemotional behaviors, including reproduction, affiliation, aggression, submission, and anxiety-like behaviors on 36 ovariectomized female rhesus monkeys. Females were exposed to graded psychosocial stress, established by an intrinsic female dominance hierarchy, where subordinate animals receive high amounts of harassment. Our data show that E2 dose-dependently increased sexual motivation and male-affiliation in dominant (e.g. low-stress) females, while subordinate females showed no positive effects of E2, even at higher doses. In addition, contact aggression was attenuated in dominant females, while non-contact aggression was attenuated in both dominant and middle-ranking females. These results suggest that the stress-induced attenuation of E2's activational effects on sexual behavior and affiliation with males may not be overcome with higher doses of E2. Furthermore, the observed behavioral consequences of psychosocial stress and E2 dose may be dependent on the behaviors of all the females in the social-group, and better resolution on these effects depends on isolating treatment to individuals within the group to minimize alterations in social-group interactions.     

Social status modifies estradiol activation of sociosexual behavior in female rhesus monkeys

Estrogen (E2) has activational effects on sexual motivation and mitigating effects on anxiety-like behaviors that can be attenuated with chronic exposure to psychosocial stress. Some studies suggest that this attenuation can be overcome by higher doses of E2, while others show that chronic psychosocial stress may alter the mechanisms of E2 function, thus reducing any positive benefit from higher doses of E2. To determine the interaction between psychosocial stress and E2 dose on behavior, we examined the scope of attenuation across a suite of socioemotional behaviors, including reproduction, affiliation, aggression, submission, and anxiety-like behaviors on 36 ovariectomized female rhesus monkeys. Females were exposed to graded psychosocial stress, established by an intrinsic female dominance hierarchy, where subordinate animals receive high amounts of harassment. Our data show that E2 dose-dependently increased sexual motivation and male-affiliation in dominant (e.g. low-stress) females, while subordinate females showed no positive effects of E2, even at higher doses. In addition, contact aggression was attenuated in dominant females, while non-contact aggression was attenuated in both dominant and middle-ranking females. These results suggest that the stress-induced attenuation of E2's activational effects on sexual behavior and affiliation with males may not be overcome with higher doses of E2. Furthermore, the observed behavioral consequences of psychosocial stress and E2 dose may be dependent on the behaviors of all the females in the social-group, and better resolution on these effects depends on isolating treatment to individuals within the group to minimize alterations in social-group interactions.     

Dominance status reversal based on pair-bond formation in the convict cichlid (Amatitlania nigrofasciata)

Dominant individuals have access to higher-quality resource; thus, reversing their dominance status would be important for subordinate individuals. Using the convict cichlid fish (Amatitlania nigrofasciata), this study examines whether forming a pair bond can reverse dominance status. Furthermore, I hypothesize that female convict cichlids will incur more dominance reversals from pair-bond formation than males. Dyadic, same-sex contests were conducted to determine dominant and subordinate individuals. Forced pairing of these individuals based on status was followed by polyadic, between-pair contests. The results indicate that individual dominance status does carry over into between-pair competition. Furthermore, dominance reversals do occur in convict cichlids and occur more frequently in females than in males. In addition, dominant males assist their mates during aggressive encounters, and these assists may account for subordinate females winning against dominant females during polyadic contests.     

Glucocorticoids of bison bulls in relation to social status

A primary response to stress is an increase in circulating adrenal glucocorticoids (GC) such as cortisol. Two hypotheses propose differential stress responses to agonistic and aggressive interactions in social groups. If subordinate animals are subjected to social and psychological stressors leading to chronic GC elevation, the 'stress of subordination' hypothesis predicts that GCs will be higher in subordinates than dominants. Alternatively, if dominant animals are subject to physiological stressors (e.g., fight at higher rates than subordinates) or hierarchies are unstable, the 'stress of domination' hypothesis predicts higher GCs in dominant individuals. Both models predict that GC levels will peak during the breeding season. We tested these predictions in bison bulls (Bison bison) using fecal steroid analysis to characterize GC concentration and behavioral observations to determine dominance rank, copulatory success, and tending status of bulls. Fecal samples were collected during 2003 from adult bison bulls during pre-rut (June), rut (July-August), and post-rut (September). Matched sample data indicated that mean GC levels (ng/g feces) of bulls strongly peaked during the 4-week rut, doubling from pre-rut to rut and then declining again during post-rut. High ranked dominant bulls maintained higher GC levels than lower ranked subordinate bulls. Dominance rank was positively correlated with copulatory success and age, and dominant bulls were more likely to tend (guard) cows as they approached estrus. There was a positive correlation between GC level and copulatory success, with prime-aged bulls (> or =7 years) obtaining the most copulations. GC levels were positively correlated with bull androgen levels determined in a previous study. These results support the 'stress of domination' hypothesis, indicating that dominant bison bulls pay a significant physiological price for high social status and the opportunity to mate.     

Can Individual Differences in History of Dominance Explain the Development of Linear Dominance Hierarchies?

Observed dominance hierarchies are often more linear than expected from randomly-formed dominance relationships, and in triads of animals attacks are distributed non-randomly. I hypothesize that an individual's history of dominance affects its probability of initiating aggressive interactions in the future and that individuals with winning records are more likely to initiate (winning begets initiating). Consistent with this hypothesis, evidence is presented that dominant individuals are more likely to attack than subordinate individuals. The winning begets initiating hypothesis may also explain why correlations between predicted dominance ranks (based on size, age etc.) and observed dominance ranks can be low: If the cost of engaging in and losing an interaction is high relative to the potential benefits of winning, then a large individual conditioned to be subordinate may refrain from contesting smaller, dominant individuals despite its actual competitive superiority.