The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

N K Popova - One of the best experts on this subject based on the ideXlab platform.

  • a pharmacological evidence of positive association between mouse Intermale Aggression and brain serotonin metabolism
    Behavioural Brain Research, 2012
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, E Terenina, Pierre Mormede, N K Popova
    Abstract:

    Abstract The neurotransmitter serotonin (5-HT) is involved in the regulation of mouse Intermale Aggression. Previously, it was shown that intensity of mouse Intermale Aggression was positively associated with activity of the key enzyme of 5-HT synthesis – tryptophan hydroxylase 2 (TPH2) in mouse brain. The aim of the present study was to investigate the effect of pharmacological activation or inhibition of 5-HT synthesis in the brain on Intermale Aggression in two mouse strains differing in the TPH2 activity: C57BL/6J (B6, high TPH2 activity, high aggressiveness) and CC57BR/Mv (BR, low TPH2 activity, low aggressiveness). Administration of 5-HT precursor l -tryptophan (300 mg/kg, i.p.) to BR mice significantly increased the 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) levels in the midbrain as well as the number of attacks and their duration in the resident-intruder test. And vice versa, administration of TPH2 inhibitor p-chlorophenylalanine (pCPA) (300 mg/kg, i.p., for 3 consecutive days) to B6 mice dramatically reduced the 5-HT and 5-HIAA contents in brain structures and attenuated the frequency and the duration of aggressive attacks. At the same time, l -tryptophan or pCPA did not influence the percentage of aggressive mice and the attack latency reflecting the threshold of aggressive reaction. This result indicated that the intensity of Intermale Aggression, but not the threshold of aggressive reaction is positively dependent on 5-HT metabolism in mouse brain.

  • c1473g polymorphism in mouse tph2 gene is linked to tryptophan hydroxylase 2 activity in the brain Intermale Aggression and depressive like behavior in the forced swim test
    Journal of Neuroscience Research, 2009
    Co-Authors: D. V. Osipova, A. V. Kulikov, N K Popova
    Abstract:

    Tryptophan hydroxylase-2 (TPH2) is the rate-limiting enzyme of brain serotonin synthesis. The C1473G polymorphism in the mouse tryptophan hydroxylase-2 gene affects the enzyme's activity. In the present study, we investigated the linkage between the C1473G polymorphism, enzyme activity in the brain, and behavior in the forced swim, Intermale Aggression, and open field tests using mice of the C57BL/6 (C/C) and CC57BR/Mv (G/G) strains and the B6-1473C (C/C) and B6-1473G (G/G) lines created by three successive backcrossings on C57BL/6. Mice of the CC57BR/Mv strain had decreased brain enzyme activity, Aggression intensity, and immobility in the forced swim test, but increased locomotor activity and time spent in the central part of the open field arena compared with animals of the C57BL/6 strain. Mice of the B6-1473G line homozygous for the 1473G allele had lower TPH2 activity in the brain, Aggression intensity, and immobility time in the forced swim test compared with animals of the B6-1473C line homozygous for the 1473C allele. No differences were found between the B6-1473G and B6-1473C mice in locomotor activity and time spent in the central part of the arena in the open field test. Thus, the C1473G polymorphism is involved in the determination of TPH2 activity and is linked to Aggression intensity and forced-swim immobility in mice. At the same time, the polymorphism does not affect locomotion and anxiety-related behavior in the open field test. The B6-1473C and B6-1473G mice represent a valuable experimental model for investigating molecular mechanisms of serotonin-related behavior. © 2008 Wiley-Liss, Inc.

  • association between tph2 gene polymorphism brain tryptophan hydroxylase activity and aggressiveness in mouse strains
    Genes Brain and Behavior, 2005
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, N K Popova
    Abstract:

    The brain neurotransmitter serotonin is involved in the regulation of aggressive behavior. The main factor determining the brain serotonin level is the activity of the rate-limiting enzyme in the biosynthesis of the neurotransmitter – tryptophan hydroxylase isoform (TPH) 2 encoded by the Tph2 gene. Recently the C1473G single-nucleotide polymorphism in the Tph2 gene was reported. Here we study the C1473G polymorphism in 10 inbred mouse strains (C57BL/6J, AKR/J, DD/He, C3H/HeJ, YT/Y, BALB/cJLac, CC57BR/Mv and A/He) and demonstrate the association of the polymorphism with brain TPH activity and Intermale aggressiveness. TPH activity in the midbrain of mice homozygous for the 1473C allele was higher than that in mice carrying 1473G alleles. A close association of the 1473C allele with increased number of attacks towards another male was found. The results support a link between the C1473G polymorphism in Tph2 gene, trypthophan hydroxylase activity and intensity of Intermale Aggression.

  • association between Intermale Aggression and genetically defined tryptophan hydroxylase activity in the mouse brain
    Aggressive Behavior, 1996
    Co-Authors: A. V. Kulikov, N K Popova
    Abstract:

    The relationship between the genetically defined intensity of Intermale Aggression and the activity of brain tryptophan hydroxylase (TPH) has been studied in inbred mice. No association between the enzyme activity and the percentage of aggressive mice (reflecting the predisposition to aggressive reaction) was revealed. However, a significant positive interstrain correlation between brain TPH activity and accumulated attacking time (reflecting fight intensity) was identified. No correlation was found between TPH activity and the accumulated attacking time in segregating F2 (BALB x C57BL) mice. In conclusion, TPH is an important, but not the only factor controlling the intensity of Intermale Aggression in mice.

J M Koolhaas - One of the best experts on this subject based on the ideXlab platform.

  • acute and repeated intranasal oxytocin administration exerts anti aggressive and pro affiliative effects in male rats
    Psychoneuroendocrinology, 2015
    Co-Authors: Federica Calcagnoli, Judith C Kreutzmann, Sietse F De Boer, Monika Althaus, J M Koolhaas
    Abstract:

    Summary Socio-emotional deficits and impulsive/aggressive outbursts are prevalent symptoms of many neuropsychiatric disorders, and intranasal administration of oxytocin (OXT) is emerging as a putative novel therapeutic approach to curb these problems. Recently, we demonstrated potent anti-aggressive and pro-social effects of intracerebroventricular (icv) OXT administration in male rats. The present study tested whether similar behavioral effects are induced when OXT is delivered intranasally. Heart-rate and blood-pressure responses were telemetrically monitored to investigate whether peripheral physiological effects were provoked after intranasal OXT administration. Intranasal OXT administration in resident animals reduced offensive Aggression and increased social exploration toward an unfamiliar male intruder. Using a partner-preference test, intranasal OXT also strengthened the bonding between the male resident and its female partner. No changes in cardiovascular (re)activity were found, indicating an absence of direct peripheral physiological effects after intranasal OXT treatment. In conclusion, although the precise route and mechanisms of nose-to-brain transport/communication remain to be elucidated, our data demonstrated intranasal OXT to be an effective application method for suppressing Intermale Aggression and enhancing social affiliation.

  • studies on wild house mice vii prenatal maternal environment and Aggression
    Behavior Genetics, 1996
    Co-Authors: F Sluyter, J M Koolhaas, J Van Der Vlugt, G A Van Oortmerssen, De Sietse Boer
    Abstract:

    The effect of the maternal environment on Intermale Aggression was studied by means of embryo transfer of genetically selected aggressive (SAL) and nonaggressive wild house mice (LAL), and their reciprocal F1's, to standard (NMRI) females. No effect was found on the attack latency scores (ALS), i.e., Aggression: all genotypes born and raised under natural conditions showed an ALS similar that of genotypes born and raised by NMRI females. Since previous studies on wild house mice failed to demonstrate postnatal effects on Aggression, and the present results indicate the absence of prenatal maternal environmental effects on Aggression, the primacy of genetic over maternal variance in the development of adult Intermale Aggression in wild house mice is indicated.

  • studies on wild house mice viii postnatal maternal influences on Intermale Aggression in reciprocal f1 s
    Behavior Genetics, 1995
    Co-Authors: F Sluyter, Geert A. Van Oortmerssen, Bianca Meijeringh, J M Koolhaas
    Abstract:

    Previous findings have shown a difference in attack latencies, i.e., Aggression, between reciprocal F1's of a line selected for short attack latency (SAL) and a line selected for long attack latency (LAL). In the present study, we investigated the influence of postnatal maternal environment on attack latency scores (ALSs). The results show that only the evolution of the ALSs over 3 consecutive days is influenced by crossfostering. Accordingly, we conclude that the postnatal maternal environment affects ALSs only to a small extent.

  • studies on wild house mice vi differential effects of the y chromosome on Intermale Aggression
    Aggressive Behavior, 1994
    Co-Authors: F Sluyter, Geert A. Van Oortmerssen, J M Koolhaas
    Abstract:

    The aim of this study is to determine the effects of different parts of the Y chromosome of wild house mice on Aggression. To reach this goal, intercrosses were made between two selection lines for attack latency (SAL and LAL) and their congenic strains (SAL.LY and LAL.SY). This procedure resulted in F1 hybrids that carried the same autosomes, but differed in their X chromosome and the two different parts of their Y chromosomes, the different parts of the Y chromosome being a recombining part called the pseudoautosomal region (PAR) and a non-recombining part (non-PAR). We conclude that both parts of the Y chromosome contribute slightly but significantly to variation in Aggression. The major effect is accomplished by the PAR of the aggressive parent; a mirror effect is achieved by the non-PAR ofthe aggressive parent in interaction with the PAR.

A. V. Kulikov - One of the best experts on this subject based on the ideXlab platform.

  • a pharmacological evidence of positive association between mouse Intermale Aggression and brain serotonin metabolism
    Behavioural Brain Research, 2012
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, E Terenina, Pierre Mormede, N K Popova
    Abstract:

    Abstract The neurotransmitter serotonin (5-HT) is involved in the regulation of mouse Intermale Aggression. Previously, it was shown that intensity of mouse Intermale Aggression was positively associated with activity of the key enzyme of 5-HT synthesis – tryptophan hydroxylase 2 (TPH2) in mouse brain. The aim of the present study was to investigate the effect of pharmacological activation or inhibition of 5-HT synthesis in the brain on Intermale Aggression in two mouse strains differing in the TPH2 activity: C57BL/6J (B6, high TPH2 activity, high aggressiveness) and CC57BR/Mv (BR, low TPH2 activity, low aggressiveness). Administration of 5-HT precursor l -tryptophan (300 mg/kg, i.p.) to BR mice significantly increased the 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) levels in the midbrain as well as the number of attacks and their duration in the resident-intruder test. And vice versa, administration of TPH2 inhibitor p-chlorophenylalanine (pCPA) (300 mg/kg, i.p., for 3 consecutive days) to B6 mice dramatically reduced the 5-HT and 5-HIAA contents in brain structures and attenuated the frequency and the duration of aggressive attacks. At the same time, l -tryptophan or pCPA did not influence the percentage of aggressive mice and the attack latency reflecting the threshold of aggressive reaction. This result indicated that the intensity of Intermale Aggression, but not the threshold of aggressive reaction is positively dependent on 5-HT metabolism in mouse brain.

  • c1473g polymorphism in mouse tph2 gene is linked to tryptophan hydroxylase 2 activity in the brain Intermale Aggression and depressive like behavior in the forced swim test
    Journal of Neuroscience Research, 2009
    Co-Authors: D. V. Osipova, A. V. Kulikov, N K Popova
    Abstract:

    Tryptophan hydroxylase-2 (TPH2) is the rate-limiting enzyme of brain serotonin synthesis. The C1473G polymorphism in the mouse tryptophan hydroxylase-2 gene affects the enzyme's activity. In the present study, we investigated the linkage between the C1473G polymorphism, enzyme activity in the brain, and behavior in the forced swim, Intermale Aggression, and open field tests using mice of the C57BL/6 (C/C) and CC57BR/Mv (G/G) strains and the B6-1473C (C/C) and B6-1473G (G/G) lines created by three successive backcrossings on C57BL/6. Mice of the CC57BR/Mv strain had decreased brain enzyme activity, Aggression intensity, and immobility in the forced swim test, but increased locomotor activity and time spent in the central part of the open field arena compared with animals of the C57BL/6 strain. Mice of the B6-1473G line homozygous for the 1473G allele had lower TPH2 activity in the brain, Aggression intensity, and immobility time in the forced swim test compared with animals of the B6-1473C line homozygous for the 1473C allele. No differences were found between the B6-1473G and B6-1473C mice in locomotor activity and time spent in the central part of the arena in the open field test. Thus, the C1473G polymorphism is involved in the determination of TPH2 activity and is linked to Aggression intensity and forced-swim immobility in mice. At the same time, the polymorphism does not affect locomotion and anxiety-related behavior in the open field test. The B6-1473C and B6-1473G mice represent a valuable experimental model for investigating molecular mechanisms of serotonin-related behavior. © 2008 Wiley-Liss, Inc.

  • association between tph2 gene polymorphism brain tryptophan hydroxylase activity and aggressiveness in mouse strains
    Genes Brain and Behavior, 2005
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, N K Popova
    Abstract:

    The brain neurotransmitter serotonin is involved in the regulation of aggressive behavior. The main factor determining the brain serotonin level is the activity of the rate-limiting enzyme in the biosynthesis of the neurotransmitter – tryptophan hydroxylase isoform (TPH) 2 encoded by the Tph2 gene. Recently the C1473G single-nucleotide polymorphism in the Tph2 gene was reported. Here we study the C1473G polymorphism in 10 inbred mouse strains (C57BL/6J, AKR/J, DD/He, C3H/HeJ, YT/Y, BALB/cJLac, CC57BR/Mv and A/He) and demonstrate the association of the polymorphism with brain TPH activity and Intermale aggressiveness. TPH activity in the midbrain of mice homozygous for the 1473C allele was higher than that in mice carrying 1473G alleles. A close association of the 1473C allele with increased number of attacks towards another male was found. The results support a link between the C1473G polymorphism in Tph2 gene, trypthophan hydroxylase activity and intensity of Intermale Aggression.

  • association between Intermale Aggression and genetically defined tryptophan hydroxylase activity in the mouse brain
    Aggressive Behavior, 1996
    Co-Authors: A. V. Kulikov, N K Popova
    Abstract:

    The relationship between the genetically defined intensity of Intermale Aggression and the activity of brain tryptophan hydroxylase (TPH) has been studied in inbred mice. No association between the enzyme activity and the percentage of aggressive mice (reflecting the predisposition to aggressive reaction) was revealed. However, a significant positive interstrain correlation between brain TPH activity and accumulated attacking time (reflecting fight intensity) was identified. No correlation was found between TPH activity and the accumulated attacking time in segregating F2 (BALB x C57BL) mice. In conclusion, TPH is an important, but not the only factor controlling the intensity of Intermale Aggression in mice.

D. V. Osipova - One of the best experts on this subject based on the ideXlab platform.

  • a pharmacological evidence of positive association between mouse Intermale Aggression and brain serotonin metabolism
    Behavioural Brain Research, 2012
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, E Terenina, Pierre Mormede, N K Popova
    Abstract:

    Abstract The neurotransmitter serotonin (5-HT) is involved in the regulation of mouse Intermale Aggression. Previously, it was shown that intensity of mouse Intermale Aggression was positively associated with activity of the key enzyme of 5-HT synthesis – tryptophan hydroxylase 2 (TPH2) in mouse brain. The aim of the present study was to investigate the effect of pharmacological activation or inhibition of 5-HT synthesis in the brain on Intermale Aggression in two mouse strains differing in the TPH2 activity: C57BL/6J (B6, high TPH2 activity, high aggressiveness) and CC57BR/Mv (BR, low TPH2 activity, low aggressiveness). Administration of 5-HT precursor l -tryptophan (300 mg/kg, i.p.) to BR mice significantly increased the 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) levels in the midbrain as well as the number of attacks and their duration in the resident-intruder test. And vice versa, administration of TPH2 inhibitor p-chlorophenylalanine (pCPA) (300 mg/kg, i.p., for 3 consecutive days) to B6 mice dramatically reduced the 5-HT and 5-HIAA contents in brain structures and attenuated the frequency and the duration of aggressive attacks. At the same time, l -tryptophan or pCPA did not influence the percentage of aggressive mice and the attack latency reflecting the threshold of aggressive reaction. This result indicated that the intensity of Intermale Aggression, but not the threshold of aggressive reaction is positively dependent on 5-HT metabolism in mouse brain.

  • c1473g polymorphism in mouse tph2 gene is linked to tryptophan hydroxylase 2 activity in the brain Intermale Aggression and depressive like behavior in the forced swim test
    Journal of Neuroscience Research, 2009
    Co-Authors: D. V. Osipova, A. V. Kulikov, N K Popova
    Abstract:

    Tryptophan hydroxylase-2 (TPH2) is the rate-limiting enzyme of brain serotonin synthesis. The C1473G polymorphism in the mouse tryptophan hydroxylase-2 gene affects the enzyme's activity. In the present study, we investigated the linkage between the C1473G polymorphism, enzyme activity in the brain, and behavior in the forced swim, Intermale Aggression, and open field tests using mice of the C57BL/6 (C/C) and CC57BR/Mv (G/G) strains and the B6-1473C (C/C) and B6-1473G (G/G) lines created by three successive backcrossings on C57BL/6. Mice of the CC57BR/Mv strain had decreased brain enzyme activity, Aggression intensity, and immobility in the forced swim test, but increased locomotor activity and time spent in the central part of the open field arena compared with animals of the C57BL/6 strain. Mice of the B6-1473G line homozygous for the 1473G allele had lower TPH2 activity in the brain, Aggression intensity, and immobility time in the forced swim test compared with animals of the B6-1473C line homozygous for the 1473C allele. No differences were found between the B6-1473G and B6-1473C mice in locomotor activity and time spent in the central part of the arena in the open field test. Thus, the C1473G polymorphism is involved in the determination of TPH2 activity and is linked to Aggression intensity and forced-swim immobility in mice. At the same time, the polymorphism does not affect locomotion and anxiety-related behavior in the open field test. The B6-1473C and B6-1473G mice represent a valuable experimental model for investigating molecular mechanisms of serotonin-related behavior. © 2008 Wiley-Liss, Inc.

  • C1473G polymorphism in mouse tph2 gene is linked to tryptophan hydroxylase-2 activity in the brain, Intermale Aggression, and depressive-like behavior in the forced swim test.
    Journal of neuroscience research, 2009
    Co-Authors: D. V. Osipova, Alexander V. Kulikov, Nina K. Popova
    Abstract:

    Tryptophan hydroxylase-2 (TPH2) is the rate-limiting enzyme of brain serotonin synthesis. The C1473G polymorphism in the mouse tryptophan hydroxylase-2 gene affects the enzyme's activity. In the present study, we investigated the linkage between the C1473G polymorphism, enzyme activity in the brain, and behavior in the forced swim, Intermale Aggression, and open field tests using mice of the C57BL/6 (C/C) and CC57BR/Mv (G/G) strains and the B6-1473C (C/C) and B6-1473G (G/G) lines created by three successive backcrossings on C57BL/6. Mice of the CC57BR/Mv strain had decreased brain enzyme activity, Aggression intensity, and immobility in the forced swim test, but increased locomotor activity and time spent in the central part of the open field arena compared with animals of the C57BL/6 strain. Mice of the B6-1473G line homozygous for the 1473G allele had lower TPH2 activity in the brain, Aggression intensity, and immobility time in the forced swim test compared with animals of the B6-1473C line homozygous for the 1473C allele. No differences were found between the B6-1473G and B6-1473C mice in locomotor activity and time spent in the central part of the arena in the open field test. Thus, the C1473G polymorphism is involved in the determination of TPH2 activity and is linked to Aggression intensity and forced-swim immobility in mice. At the same time, the polymorphism does not affect locomotion and anxiety-related behavior in the open field test. The B6-1473C and B6-1473G mice represent a valuable experimental model for investigating molecular mechanisms of serotonin-related behavior.

  • association between tph2 gene polymorphism brain tryptophan hydroxylase activity and aggressiveness in mouse strains
    Genes Brain and Behavior, 2005
    Co-Authors: A. V. Kulikov, D. V. Osipova, V S Naumenko, N K Popova
    Abstract:

    The brain neurotransmitter serotonin is involved in the regulation of aggressive behavior. The main factor determining the brain serotonin level is the activity of the rate-limiting enzyme in the biosynthesis of the neurotransmitter – tryptophan hydroxylase isoform (TPH) 2 encoded by the Tph2 gene. Recently the C1473G single-nucleotide polymorphism in the Tph2 gene was reported. Here we study the C1473G polymorphism in 10 inbred mouse strains (C57BL/6J, AKR/J, DD/He, C3H/HeJ, YT/Y, BALB/cJLac, CC57BR/Mv and A/He) and demonstrate the association of the polymorphism with brain TPH activity and Intermale aggressiveness. TPH activity in the midbrain of mice homozygous for the 1473C allele was higher than that in mice carrying 1473G alleles. A close association of the 1473C allele with increased number of attacks towards another male was found. The results support a link between the C1473G polymorphism in Tph2 gene, trypthophan hydroxylase activity and intensity of Intermale Aggression.

Georges Chapouthier - One of the best experts on this subject based on the ideXlab platform.

  • mice selected for differences in sensitivity to a benzodiazepine receptor inverse agonist vary in Intermale Aggression
    Neurogenetics, 1999
    Co-Authors: Pascale V Guillot, Wim E. Crusio, Frans Sluyter, Georges Chapouthier
    Abstract:

    Brain γ-aminobutyric acid (GABA) levels are involved in Intermale Aggression in mice. It was therefore expected that animals genetically selected for their sensitivity to the convulsive effects of methyl β-carboline-3-carboxylate (β-CCM; BS, β-CCM sensitive, and BR, β-CCM resistant), a benzodiazepine (BZ) inverse agonist that specifically binds to the BZ site on the GABA-A receptor complex, would differ in their levels of aggressive behavior. Using two different Aggression tests, in two independent experiments, we showed that BS mice are more aggressive than BR animals. The precise mechanisms underlying the observed line differences in β-CCM sensitivity and Aggression remain to be determined.

  • Intermale Aggression, GAD activity in the olfactory bulbs and Y chromosome effect in seven inbred mouse strains
    Behavioural Brain Research, 1998
    Co-Authors: Pascale-valérie Guillot, Georges Chapouthier
    Abstract:

    The capacity to attack a passive standard opponent in a resident-intruder test and the GAD activity in the olfactory bulbs were measured in 140 male mice from seven different inbred mouse strains. The effect of the non-pseudo autosomal region of the Y-chromosome (YNPAR) on these two phenotypes has also been investigated using a quartet of reciprocal strains congenic for the YNPAR. A strong negative correlation was found between the two variables but the YNPAR is not involved. This result suggests that males of more attacking strains have a lower olfactory threshold, making the olfactory discrimination of the opponent easier and its identification as a stranger more efficient.

  • olfaction gabaergic neurotransmission in the olfactory bulb and Intermale Aggression in mice modulation by steroids
    Behavior Genetics, 1996
    Co-Authors: Pascale V Guillot, Georges Chapouthier
    Abstract:

    A model to explain individual differences in mice for the propensity to attack male conspecifics is proposed. In the first part of the paper, the relation between olfaction and Intermale Aggression is discussed emphasizing the importance of olfactory cues provided by the opponent and their subsequent processing by the attacking male. The physiological role of GABA in the olfactory pathway is presented in the second part of the paper. The third part investigates the possible modulating action of steroids on the GABA-A receptor complex, Intermale Aggression, and olfaction. We hypothesize that at least part of the individual differences in the propensity to attack may be explained by a differential olfactory recognition and discrimination of the opponent as a stranger through a differential processing threshold of the olfactory cues provided by the urine of the opponent. A possible modulation of this threshold by steroids, especially testosterone, is also discussed.

  • Intermale Aggression and dark light preference in ten inbred mouse strains
    Behavioural Brain Research, 1996
    Co-Authors: Pascale V Guillot, Georges Chapouthier
    Abstract:

    The capacity of males to attack a passive standard opponent in a resident-intruder test and the preferences in a dark/light choice situation were measured in 200 male mice from 10 different inbred mouse strains. Large strain differences were found for all variables recorded, i.e., the proportion of attacking males, the time spent in the brightly lit box, and the number of transitions between the lit and the dark boxes. A strong negative correlation was found between the first two variables. This result suggests that males of more attacking strains have a higher level of anxiety but do not differ for their level of activity. An involvement of GABA as mediating factor is suggested.