[Effects of prenatal influences of buspirone and stress on indices of inflammatory pain response and depressive behaviour in adult rats].

New data on complex realization of anxiolytic, antidepressive and antinociceptive effects of prenatal injections of a 5-HT1A agonist buspirone were obtained in prenatally stressed adult rats. Buspirone was injected to female rats from the 9th to 21st days of pregnancy; during the last week of pregnancy buspirone was injected 10 min before immobilization stress. In the adult offspring of both sexes, behavioral indices of tonic pain response in the formalin test and the indices of depression in the forced swim test were investigated. The choice of the target was defined in accordance with available literature data on the role of 5-HT1A receptors in the mechanisms of prenatal stress, of formation of the ascending link of the nociceptive system, of development of depression, and in the mechanisms of the treatment ofnociceptive information. Prenatal stress increased the duration of licking and the time of immobility, the indices of tonic pain and depression in the rats of both sexes. Buspirone evoked the decrease of the indices investigated in prenatally stressed rats in both tests in comparison with the relevant indices in prenatally stressed rats that were not subjected to buspirone. Thereby, it has been demonstrated that buspirone normalized the indices of the tonic pain response modified by prenatal stress; a considerable decrease of the index of depression suggests that there are differences in mechanisms of antinociceptive and antidepressive effects of buspirone. The data on complex realization of anxiolytic, antidepressive and antinociceptive effects ofbuspirone stimulate the attention of clinicians and prompt further investigations in this direction.

Interrelationship between measures of pain reactions in inflammation and levels of depression in prenatally stressed rat pups.

The interrelationship between measures of pain reactions (number of flexion + shaking patterns) in the formalin test and the level of depression (duration of immobility) in the forced swimming (Porsolt) test was studied in prenatally stressed rat pups aged 7-8 days. Two series of experiments were performed, with different sequences of tests separated by intervals of one day. In the first series of experiments, the Porsolt test was performed first; in the second series, the formalin test was performed before forced swimming. The sequence of tests was found to have different effects on measures of pain and depression and their correlation in prenatally stressed and unstressed rat pups. The effects of the sequence of the depression test (before or after the formalin test) on measures of depression were different in prenatally unstressed and stressed rat pups. In the former there were no differences between the two test sequences, while in prenatally stressed rat pups the first sequence showed a significant increase in the duration of immobility. The order of testing had no effect on the pain response--there were no differences between the numbers of flexion + shaking patterns in either prenatally stressed rat pups or unstressed animals; measures of the pain response were significantly greater in the sequence in which the formalin test was followed by the Porsolt test in prenatally stressed individuals as compared with unstressed animals. A positive correlation between study parameters was seen in the first series in prenatally unstressed rat pups, while there was a negative correlation in prenatally stressed animals. In the second series, there were no significant relationships between measures. Thus, the sequelae of postnatal stress, as imposed by each test the day before the final test, were apparent only in prenatally stressed animals in terms of the level of depression.

[Infants stage of rat development in behavioral parameters of depression-like state and pain response].

In the 7-8- and the 10-11-day old male rat pups born to dams exposed to an immobilization stress for the last week of pregnancy and to the dams exposed to no stress (control), behavioral parameters were studied: the level of depression in the test of forced swimming (the Porsolt's test) and 24 h after a long pain response during inflammation (the formalin test--a subcutaneous injection of 2.5% formalin into the hind leg plantar pad). In control pups, significant age-related changes in the forced swimming were revealed: the immobility time was longer in animals of the older age group, whereas no age differences were found in parameters of the persistent inflammatory pain and in flexing + shaking behavior. The prenatal stress produced an increase in the immobility time and the flexing + shaking behavior in the 7-8-day old, but not in the 10-11-day old pups. This resulted in elimination of the age differences in the immobility time in the prenatally stressed animals. Thus, use if different methodic approaches has allowed peculiarities in the parameters of the degree of depression and duration of the pain response at inflammation in the 7-8- and 10-11-day old rat pups, which indicates heterogeneity of the infant development stage that, according to literature data, includes in rats the period from the 5th to the 10th postnatal days.

[Relationships between indices of persistent inflammatory pain response and the level of depression in prenatally stressed rats].

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.