Relationships between indices of persistent inflammatory pain response and the level of depression in prenatally stressed rats
Mikhaĭlenko, V.A.; Butkevich, I.P.; Vershinina, E.A.; Semenov, P.O.
Rossiiskii Fiziologicheskii Zhurnal Imeni I.M. Sechenova 94(12): 1384-1392
2008
ISSN/ISBN: 0869-8139 PMID: 19198183 Document Number: 621343
Relationships between behavioral indices of inflammatory pain response (the number of flexes + shakes) in the formalin test and the level of depression in forced swim in Porsolt test (immobility time) were investigated in 7-8-day-old male Wistar rats born to the dams exposed during the last week of pregnancy to immobilization stress. Two series of experiments differed in sequence of two testing procedures given 24 hr apart. In the first series of experiments Porsolt test was the first, in the second series, the formalin test preceded forced swim. It was found that the sequence of the tests effects differentially on the indices of the pain response and the level of depression as well as on their correlation in prenatally stressed (PS) and non-stressed (PNS) rats. No differences in the level of depression were apparent in PNS pups under both sequences of testing, whereas PS pups showed increase in the time of immobility in the first series of experiments. The sequence of testing had no effect on pain response indices. In the second series, the indices of pain response were increased in PS rats as compared to PNS ones. In PNS rats a positive correlation between the indices of the level of depression and the pain reaction was revealed, while in PS animals, a negative correlation was found. There was no significant dependence between the indices of depression and pain in the second series of experiments. Thus, effects of postnatal stress associated with both testing procedures applied before the final test are evident only in PS rats as to indices of the level of depression.