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IMIPRAMINE NORMALIZES NATURALLY‐OCCURRING AND DRUG‐INDUCED DIFFERENCES IN THE EXPLORATORY ACTIVITY OF RATS
Author(s) -
HARRISONREAD P.E.,
STEINBERG HANNAH
Publication year - 1980
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1980.tb07933.x
Subject(s) - imipramine , saline , psychology , behavioural despair test , medicine , endocrinology , pharmacology , chemistry , antidepressant , neuroscience , hippocampus , alternative medicine , pathology
1 Exploratory activity of female hooded rats was measured in a Y maze on two occasions, 1 week apart. Locomotion (maze arm entries), rearing, and head‐dipping into pots were scored for 5 min at each trial. 2 In control rats, differences between individuals in the amount of locomotion and rearing were consistent, as shown by significant test‐retest correlations ( r = +0.55, and +0.83 respectively). There was no correlation between head‐dipping scores obtained in the two tests. 3 Imipramine (Imip) pretreatment before the second trial (10 mg/kg i.p. on the 3 preceding days, and 2.5 mg/kg 1 h before) abolished these correlations. The scatter of the scores about the mean was also reduced by Imip, but there was no significant change in mean scores. Thus Imip appeared to have a ‘normalizing’ effect on locomotion and rears: after pretreatment, scores tended to be more uniform, and no longer reflected naturally‐occurring individual differences. 4 Imip abolished the changes in exploratory activity produced by drugs which alter brain 5‐hydroxytryptamine metabolism: p ‐chlorophenylalanine (100 mg/kg 24 h before testing) increased and dl ‐5‐hydroxytryptophan (12.5 mg/kg 1 h before testing) decreased the fall in activity over the trial in saline‐treated rats but not that in Imip‐treated rats. In this case, Imip also produced an overall reduction in activity scores. 5 The normalizing effects of Imip on rat behaviour may be analogous to its therapeutic effects in human depressive disorders.