TY - JOUR
T1 - Motor and locomotor responses to systemic amphetamine in three lines of selectively bred Long-Evans rats
AU - Brudzynski, Stefan M.
AU - Gibson, Brittany
AU - Silkstone, Michael
AU - Burgdorf, Jeffrey
AU - Kroes, Roger A.
AU - Moskal, Joseph R.
AU - Panksepp, Jaak
N1 - Funding Information:
The study was funded by a research grant from the Institute for the Study of Affective Neuroscience (S.M.B.) and Hope for Depression Research Foundation (J.B., J.M., J.P.), and partially supported by the Natural Sciences and Engineering Research Council of Canada (S.M.B.). The researchers would like to express their thanks to the excellent technical help of Ms. Dayle Belme, Mr. Thomas Eles, and Ms. Shannon Duffus.
PY - 2011/11
Y1 - 2011/11
N2 - The goal of the study was to measure spontaneous and amphetamine-induced motor and locomotor activity in three selectively bred lines of male Long-Evans rats. The number of 50 kHz ultrasonic vocalizations (USVs) emitted in response to heterospecific play with human hand ("tickling") had been measured daily in these lines of rats from 21 to 24 days of age, as a criterion for dividing them into high vocalizing line, low vocalizing line, and random breeding and testing lines. This study sought to determine whether selection of rats based on their affective social-vocalizations also had effects on their locomotor performance and sensitivity to amphetamine. In this study adult animals from the 25th generation (with no further selection) were tested. The results showed that rats, which were selectively bred to emit high numbers of 50 kHz vocalizations, also exhibited elevated levels of spontaneous locomotor activity. After systemic injection of d-amphetamine (1.5 mg/kg), the level of motor and locomotor activity significantly increased further in all the lines as compared to saline controls. The horizontal and vertical activities and the distance covered by rats of the high line, both at the baseline and after amphetamine challenge, were significantly higher than those of the low line animals in absolute scores but not as proportion of relevant saline controls. Since appetitive 50 kHz USVs and locomotor activity are both dependent on the activity of the dopamine system, it is concluded that selection of rats based on the expression of their positive emotional state is also selecting other features than vocalization, namely locomotor behavior. This may help explain why these animals are relatively resistant to depressogenic manipulations.
AB - The goal of the study was to measure spontaneous and amphetamine-induced motor and locomotor activity in three selectively bred lines of male Long-Evans rats. The number of 50 kHz ultrasonic vocalizations (USVs) emitted in response to heterospecific play with human hand ("tickling") had been measured daily in these lines of rats from 21 to 24 days of age, as a criterion for dividing them into high vocalizing line, low vocalizing line, and random breeding and testing lines. This study sought to determine whether selection of rats based on their affective social-vocalizations also had effects on their locomotor performance and sensitivity to amphetamine. In this study adult animals from the 25th generation (with no further selection) were tested. The results showed that rats, which were selectively bred to emit high numbers of 50 kHz vocalizations, also exhibited elevated levels of spontaneous locomotor activity. After systemic injection of d-amphetamine (1.5 mg/kg), the level of motor and locomotor activity significantly increased further in all the lines as compared to saline controls. The horizontal and vertical activities and the distance covered by rats of the high line, both at the baseline and after amphetamine challenge, were significantly higher than those of the low line animals in absolute scores but not as proportion of relevant saline controls. Since appetitive 50 kHz USVs and locomotor activity are both dependent on the activity of the dopamine system, it is concluded that selection of rats based on the expression of their positive emotional state is also selecting other features than vocalization, namely locomotor behavior. This may help explain why these animals are relatively resistant to depressogenic manipulations.
KW - 50 kHz vocalization
KW - Amphetamine
KW - Breeding for vocalization
KW - Horizontal activity
KW - Locomotor activity
KW - Positive emotional state
KW - Vertical activity
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U2 - 10.1016/j.pbb.2011.08.006
DO - 10.1016/j.pbb.2011.08.006
M3 - Article
C2 - 21867727
AN - SCOPUS:80052529088
SN - 0091-3057
VL - 100
SP - 119
EP - 124
JO - Pharmacology, Biochemistry and Behavior
JF - Pharmacology, Biochemistry and Behavior
IS - 1
ER -