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Behavioural responses to olfactory bulbectomy in rats maintained in reversed cycle lighting
363 References
M611er, H.J. (1992) Pharmacopsychiatry 25, 249-253. Ottevanger, E.A. (1991) Eur. J. Clin. Res. 1, 47 54.
Behavioural responses to olfactory bulbectomy in rats maintained in reversed cycle lighting
J.P. Kelly a, T.R.
Norman b and
B.E.
Leonard a
~'Department (?/ Pharmacology, University College, Galway, h'eland and t'Department Of Psychiatry, University ~?/ Melbourne. Austin Hospital, HeMelherg 3084, Australia Key word~. Olfactory bulbectomy; "Open field'; Elevated plus-maze; Morris maze; Corticosterone The bilateral olfactory bulbectomised (OB) rat has been proposed as an animal model of depression (van Riezen and Leonard, 1990). A characteristic pattern of behavioural hyperactivity in the 'open field' (Jancsar and Leonard, 1983) and deficits in passive avoidance behaviour (van Riezen et al., 1976) are observed following bulbectomy. The aim of the present stud3) was to compare behavioural responses of individually and group-housed rats following bulbectomy with appropriate sham-operated controls in conditions of reversed cycle lighting. Male Sprague-Dawley rats weighing 25(~280 g were acclimatised for 7 days to reversed cycle lighting in the animal house before bilateral olfactory bulbectomy. Body weight, food and water consumption were monitored daily and behavioural observations performed at least 2 weeks after the operation. 'Open field', elevated plus-maze and performance in the Morris water maze were monitored on consecutive days. Blood samples were obtained on day 21 following surgery and serum corticosterone levels were determined at 01.00 h. The results from group- and singly housed animals are shown in the Table. The results show' that the development of hyperactivity in OB rats compared to sham-operated animals with a tendency for singly housed animals to have a greater activity. Performance in the Morris maze was impaired in OB rats, which suggests that deficits in the cholinergic system occur following bulbectomy.
Table 1. Behavioural and corticosterone responses in sham and OB rats "Open field" (ambulation)
Plus-maze (open entries)
Morris maze latency (st day 2
Group-housed SO(N = 7) OB (N = 7)
Singly housed SO(N = 6) OB (N = 5)
77 ± 34 140 _+ 58*
114 ± 29 162 ± 39**
Corticosterone (iLg/dl)
day 3
4 _+ 3 10"
14 ± 4 34 + 14"*
7 ± 6 22 _+ 14"
4.8 ± 0.7 12.9 + 2.8*
3 i 1 9 + 6*
19 + II 40 ± 18"
10 _+ 10 48 ± 24*
8.8 ± 1.6 ~ 12.8 ± 2.1
10 +
Behavioural data are expressed as median _+ SD; corticosterone data are expressed as mean _+ SEM. *P<0.05, **P<0.01 vs. relevant sham-operated control. ~ P<0.05 vs. singly housed sham-operated group.
Acknowledgement: T.R.N. was supported by a Wellcome-Ramciotti Research Travel Grant during the course of this study. References
Jancsar, S. and Leonard, B.E. (1983) The olfactory bulbectomized rat as a model of depression. In: E. Usdin et al. (Eds.), Frontiers in Neuropsychiatric Research. MacMillan, New York, pp. 357-372. van Riezen, H. and Leonard, B.E. (1990) Effects of psychotropic drugs on the behaviour and neurochemistry of olfactory bulbectomized rats. Pharmacol. Ther. 47, 21 34.
M611er, H.J. (1992) Pharmacopsychiatry 25, 249-253. Ottevanger, E.A. (1991) Eur. J. Clin. Res. 1, 47 54.
Behavioural responses to olfactory bulbectomy in rats maintained in reversed cycle lighting
J.P. Kelly a, T.R.
Norman b and
B.E.
Leonard a
~'Department (?/ Pharmacology, University College, Galway, h'eland and t'Department Of Psychiatry, University ~?/ Melbourne. Austin Hospital, HeMelherg 3084, Australia Key word~. Olfactory bulbectomy; "Open field'; Elevated plus-maze; Morris maze; Corticosterone The bilateral olfactory bulbectomised (OB) rat has been proposed as an animal model of depression (van Riezen and Leonard, 1990). A characteristic pattern of behavioural hyperactivity in the 'open field' (Jancsar and Leonard, 1983) and deficits in passive avoidance behaviour (van Riezen et al., 1976) are observed following bulbectomy. The aim of the present stud3) was to compare behavioural responses of individually and group-housed rats following bulbectomy with appropriate sham-operated controls in conditions of reversed cycle lighting. Male Sprague-Dawley rats weighing 25(~280 g were acclimatised for 7 days to reversed cycle lighting in the animal house before bilateral olfactory bulbectomy. Body weight, food and water consumption were monitored daily and behavioural observations performed at least 2 weeks after the operation. 'Open field', elevated plus-maze and performance in the Morris water maze were monitored on consecutive days. Blood samples were obtained on day 21 following surgery and serum corticosterone levels were determined at 01.00 h. The results from group- and singly housed animals are shown in the Table. The results show' that the development of hyperactivity in OB rats compared to sham-operated animals with a tendency for singly housed animals to have a greater activity. Performance in the Morris maze was impaired in OB rats, which suggests that deficits in the cholinergic system occur following bulbectomy.
Table 1. Behavioural and corticosterone responses in sham and OB rats "Open field" (ambulation)
Plus-maze (open entries)
Morris maze latency (st day 2
Group-housed SO(N = 7) OB (N = 7)
Singly housed SO(N = 6) OB (N = 5)
77 ± 34 140 _+ 58*
114 ± 29 162 ± 39**
Corticosterone (iLg/dl)
day 3
4 _+ 3 10"
14 ± 4 34 + 14"*
7 ± 6 22 _+ 14"
4.8 ± 0.7 12.9 + 2.8*
3 i 1 9 + 6*
19 + II 40 ± 18"
10 _+ 10 48 ± 24*
8.8 ± 1.6 ~ 12.8 ± 2.1
10 +
Behavioural data are expressed as median _+ SD; corticosterone data are expressed as mean _+ SEM. *P<0.05, **P<0.01 vs. relevant sham-operated control. ~ P<0.05 vs. singly housed sham-operated group.
Acknowledgement: T.R.N. was supported by a Wellcome-Ramciotti Research Travel Grant during the course of this study. References
Jancsar, S. and Leonard, B.E. (1983) The olfactory bulbectomized rat as a model of depression. In: E. Usdin et al. (Eds.), Frontiers in Neuropsychiatric Research. MacMillan, New York, pp. 357-372. van Riezen, H. and Leonard, B.E. (1990) Effects of psychotropic drugs on the behaviour and neurochemistry of olfactory bulbectomized rats. Pharmacol. Ther. 47, 21 34.