Increased Number of Neurons Expressing Androgen Receptor in the Basolateral Amygdala of Pathologically Aggressive Dogs

Abstract

The present study aimed to determine the extent to which the androgen receptor (AR) is directly involved in the hormonal modulation of pathological canine aggressive behaviour in the basolateral nuclear group (BNG) of the amygdaloid body. A stereological quantification of AR-positive neurons was performed in the BNGs of normally behaving and aggressive male dogs. The BNG was selected because it is involved in sexual and behavioural activities that are influenced by androgens. In the aggressive dogs the BNG contained a significantly higher number of AR-positive neurons compared with normally behaving dogs suggesting differences in androgen activity within the BNGs of both the groups. However, additional mechanisms are likely to be involved because the AR-negative fraction of BNG neurons was also increased in the aggressive dogs. It was concluded that most of the AR was unliganded because a cytoplasmic staining pattern of AR positivity was observed in the canine BNG neurons. This indicates that genomic androgen actions, which are mediated through the AR are of minor importance in the testosterone modulation of canine aggression within the BNG. Other non-genomic mechanisms through which androgens may exert their action in the BNG are discussed. The aromatase pathway is suggested to be the main mechanism through which testosterone exerts its action within the BNG.

The Role of Testosterone in Sexuality and Paraphilia—A Neurobiological Approach. Part I: Testosterone and Sexuality

“…Bezdickova et al observed nuclear ARs staining within the mammillary body, precentral gyrus, and hippocampus of tissue taken post mortem from the brains of two men [22]. Apart from the hypothalamus and the hippocampus, ARs seem also to be located in the amygdala, as demonstrated in rats, dogs, and monkeys [17,24,25]. Finally, even cortical areas were found to be target sites for androgens, particularly the prefrontal cortex and the temporal cortex of rats, monkeys, and humans [17,22,[26][27][28][29].…”

Approach–Avoidance versus Dominance–Submissiveness: A Multilevel Neural Framework on How Testosterone Promotes Social Status

“…The effects of testosterone on the BLA’s vasopressin system has, to our knowledge, not yet been studied, but given testosterone’s fear-reducing qualities, it seems unlikely that testosterone also upregulates vasopressin in the BLA like it does in the CMA. This, however, does not exclude that testosterone affects the BLA, but this influence might be more direct on androgen receptors as these have been shown to be increased in the BLA of pathologically aggressive dogs (Jacobs, van den Broeck, & Simoens, 2006).…”

Potential of zebrafish as a model for exploring the role of the amygdala in emotional memory and motivational behavior

“…Experimental evidence from various mammalian models suggests that the amygdalar complex might also be involved in aggressive behavior. The expression of androgen receptor is increased in the basolateral complex in aggressive dogs (Jacobs et al, 2006); amygdalectomy reduces aggression in rhesus monkeys (Butter and Snyder, 1972); and lesions to the central amygdala alter aggressive behavior in cats (Zagrodzka et al, 1998), rats (Vochteloo and Koolhaas, 1987), and mice (Wang et al, 2013).…”