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ABSTRACT: The present study aimed to quantify neurons expressing the serotonin-1B receptor and evaluate numerical differences in normally behaving and pathologically aggressive dogs in order to assess whether the serotonin-1B receptor is involved in pathological canine aggression. Because previous studies have reported structural alterations in the basolateral nuclear group (BNG) of the amygdaloid body of aggressive dogs, this structure was selected as region of interest in the present study. Indirect immunohistochemistry was applied to visualise the serotonin-1B-receptor-positive neurons. Immunoreactivity was located predominantly within the neuronal cell bodies and adjacent neuronal processes. In the aggressive dogs the BNGs contained a significantly higher number of serotonin-1B-receptor-positive neurons compared to the normally behaving dogs. This number was strongly correlated with the total number of neurons per BNG, which was also significantly increased in aggressive dogs compared to normal dogs. The percentage of neurons expressing the serotonin-1B receptor did not differ significantly between both groups. No significant asymmetries were observed for the number and percentage of serotonin-1B-receptor-positive neurons. Potential relationships between the present findings and the etiology of aggressive behaviour, the neuroprotective role of the serotonin-1B receptor and receptor dysfunction are discussed.
Brain Research 04/2007; 1136(1):102-9. · 2.73 Impact Factor
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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.
Journal of Veterinary Medicine Series A 10/2006; 53(7):334-9. · 0.93 Impact Factor
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ABSTRACT: Substance P and its NK-1 receptor are involved in the modulation of aggressive behavior. Because of the role of the basolateral nuclear group (BNG) of the amygdala in canine aggression, neurokinin-1 receptor (NK-1) immunoreactivity in this brain region was assessed stereologically in 7 normally behaving and 6 pathologically aggressive dogs. The first aim of this study was to obtain information about the absolute number of neurons expressing the NK-1 receptor in the canine BNG because absolute numbers of neurons expressing the NK-1 receptor are not documented in literature. Additionally, an exploratory comparison was made between NK-1 expressing neurons in the BNGs of normally behaving and aggressive dogs. Results showed a very low amount (1-2%) of BNG neurons containing the NK-1 receptor in both groups. Aggressive dogs had significantly more NK-1-receptor-positive BNG neurons than normal dogs, but the numerical densities and fractions of receptor-positive neurons did not differ significantly between both groups. Combined with the fact that aggressive dogs have 27% more neurons in their BNGs than normal dogs, as reported in a previous study, these findings suggest a limited role for the NK-1-receptor-positive neurons within the BNG in the modulation of canine aggression. The present report of absolute numbers of neurons expressing the NK-1 receptor in the canine BNG could however be useful for further quantitative studies.
Brain Research 08/2006; 1098(1):106-12. · 2.73 Impact Factor
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ABSTRACT: Involvement of the basolateral nuclear group (BNG) in pathological canine aggression was assessed by stereological determination of the volume of the BNG and quantification of the numerical density and total number of BNG neurons in normally behaving and aggressive dogs. A bilateral BNG enlargement of 40% was observed in the aggressive group. This enlargement appeared to be caused by a significantly increased number of BNG neurons. Other alterations such as an increased vessel density, oedema and scar tissue were not observed in any of the examined BNGs. The potential role of neurotrophins and stress hormones in the increased number of BNG neurons is discussed.
Behavioural Brain Research 07/2006; 170(1):119-25. · 3.42 Impact Factor
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ABSTRACT: A protocol was developed for the stereological quantification of neurons expressing androgen receptor (AR) in the basolateral nuclear group (BNG) of the canine amygdaloid body. The Cavalieri method was used to estimate the BNG volume and the physical disector technique was applied for assessing the numerical densities and total numbers of both ordinary and AR-positive BNG neurons. The overall number of BNG neurons and the BNG volume were assessed on Nissl-stained sections, while AR was visualised using indirect immunohistochemistry. The morphological differentiation between neurons, astrocytes, and oligodendrocytes in these immunohistochemical sections was hampered by the cytoplasmic localisation of AR in these cells. Therefore, an additional criterion was developed based on the nuclear diameters of these cells. With the cutoff value of 7.4 microm, a sensitivity of 97.7% and specificity of 97.6% were obtained. A negative correlation was found between the BNG volume and the numerical density of its neurons, implicating that a large BNG will not necessarily have a higher number of neurons. Therefore, the numerical density or BNG volume should always be assessed in addition to the total number of neurons, justifying the use of the physical disector instead of the fractionator technique in the present study. However, higher coefficients of error were obtained for the total number of neurons with the physical disector method because of the indirect measurement of cell numbers. Therefore, the precision of the estimates must be high enough when using the disector method to compensate the precision loss caused by this indirect calculation of the total cell number.
Brain Research Protocols 08/2005; 15(2):92-104. · 1.82 Impact Factor
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ABSTRACT: In this review the variety of parameters used for evaluating the pathological extent of aggressive behaviour is summarised and the practical usefulness of each parameter is discussed. The selected parameters are: the objective analytic description of the aggressive behaviour, the function of the aggression, the presence of the three phases of a normal aggression sequence, the number of bites per attack, the duration of the attack and the frequency of the aggressive behaviour. Other criteria such as the appropriateness of the aggression in relation to the context, the predictability of the aggression and the severity of the caused injury are biased because of the variation caused by numerous external factors. The relevance of the most suitable parameters will be assessed in a further study in which the distribution of aggression modulating neurotransmitter receptors will be determined.
The Veterinary quarterly 07/2003; 25(2):53-60. · 1.47 Impact Factor
