TY - JOUR
T1 - Differential behavioral and neurochemical effects following lesions of the dorsal or median raphe nuclei in rats
AU - Jacobs, Barry L.
AU - Wise, William D.
AU - Taylor, Kenneth M.
N1 - Funding Information:
This investigation was supported by Grants MH 24771 and MH 23433 from the National Institute of Mental Health. We thank Daniel Ruimy for assistance in conducting these experiments, and Donna Kirk for assistance in the preparation of this manuscript.
PY - 1974/10/25
Y1 - 1974/10/25
N2 - Locomotor activity and regional forebrain levels of serotonin (5-HT) were measured following the placement of electrolytic lesions in either the dorsal or median raphe nucleus of adult male rats. In the first two experiments, control lesions were placed in the brachium conjunctivum, and in the third experiment, a sham lesion group served as control. Median lesions significantly increased locomotor actiivity as measured in tilt cages, by 250-300% on the second day post-lesion, and this elevation stabilized at approximately 100% above control levels on day 9 post-lesion. There were no statistically significant differences in the amount of locomotor activity in the dorsal, brachium or sham lesioned groups on any post-lesion day. When the amount of 5-HT depletion was measured 5 days post-lesion, it was found that the dorsal (D) and median (M) lesions produced similar reductions in cerebral cortex (D - 40%; M - 31%); hypothalamus (D - 54%; M - 58%) and striatum (D - 50%; M - 29%). However, the effects of the two lesions were markedly different in the hippocampus. The dorsal lesion produced a non-significant 10% reduction in hippocampal 5-HT level, while the median lesion caused an 82% reduction. On the basis of these data it is hypothesized that a reduction in hippocampal 5-HT may account for the increased activity in the median lesioned group.
AB - Locomotor activity and regional forebrain levels of serotonin (5-HT) were measured following the placement of electrolytic lesions in either the dorsal or median raphe nucleus of adult male rats. In the first two experiments, control lesions were placed in the brachium conjunctivum, and in the third experiment, a sham lesion group served as control. Median lesions significantly increased locomotor actiivity as measured in tilt cages, by 250-300% on the second day post-lesion, and this elevation stabilized at approximately 100% above control levels on day 9 post-lesion. There were no statistically significant differences in the amount of locomotor activity in the dorsal, brachium or sham lesioned groups on any post-lesion day. When the amount of 5-HT depletion was measured 5 days post-lesion, it was found that the dorsal (D) and median (M) lesions produced similar reductions in cerebral cortex (D - 40%; M - 31%); hypothalamus (D - 54%; M - 58%) and striatum (D - 50%; M - 29%). However, the effects of the two lesions were markedly different in the hippocampus. The dorsal lesion produced a non-significant 10% reduction in hippocampal 5-HT level, while the median lesion caused an 82% reduction. On the basis of these data it is hypothesized that a reduction in hippocampal 5-HT may account for the increased activity in the median lesioned group.
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U2 - 10.1016/0006-8993(74)90433-8
DO - 10.1016/0006-8993(74)90433-8
M3 - Article
C2 - 4420173
AN - SCOPUS:0016259783
SN - 0006-8993
VL - 79
SP - 353
EP - 361
JO - Brain Research
JF - Brain Research
IS - 3
ER -