Stress-Induced Changes of the Immunological Status of Young Rats of Both Sexes

Denefil O. V., Mits I. R.

CLINICAL AND EXPERIMENTAL MEDICINE

Scentific article

The paper considers separate and combined effect of prenatal and postnatal stress on the immuno­ logical values of young rats of both sexes. Experiments were performed on 44 mongrel sexually mature male rats and on 49 females aged 3 months. Preg­ nant females were kept for one hour in narrow plastic cases in the first part of the day within 15­20 gestation days to induce prenatal stress. The neonatals were kept on standard vivarium dietary intake. Postnatal stress was induced in young animals since 1.5 months’ age by keeping them in cramped cages till 3 months’ age. On the experimental day, the rats were fixed supine for one hour. Combined stress included the effect of pre­and postnatal stress. The concentration of serum immunoglobulins (Ig) – IgA, IgM, IgG and the content of circulating immune com­ plexes (CIC) were determined. Digital data were statistically processed with “Excel” (“Microsoft, USA) and “STATISTICA” 6.0 (“Statsoft”, USA) using parametric and non­parametric methods of data evaluation. In control male rats, the CIC content was by 10.51 per cent higher (p < 0.001) than in females. The stress impact resulted in growing CIC irrespective of the sex and stress type. The maximum growth for males was found under combined (85.48 per cent, p < 0. 01) and prenatal (74.70 per cent, p < 0.001) stress. The females revealed reliable CIC growth under prenatal (2.15 times, p < 0.001), postnatal (2.07 times, p < 0.001) and combined stress (2.06, p < 0.001). Under the prenatal and postnatal stress, the CIC concentration was reliably higher in females in compari­ son with male rats whereas no sexual difference was found under combined stress. The study of blood Ig concentration revealed higher IgA level in females in comparison with male rats (by 3.65 per cent, p < 0.02) whereas the concentration of IgM and IgG in young intact rats proved to be sex­independent. The stress led to reliable growth in concentration of all Ig types irrespective of the sex and the way of stress induction. If compared to the rest of immunoglobulins, the IgA showed the highest concentration growth both in male and female rats. The prenatal stress resulted in 2.75 times growth (p < 0.001) in males and 2 45 times (p < 0.001) – in females, the values for the postnatal and combined stress being 2.02 (p < 0.01) and 2.20 (p < 0.001); 2.23 (p < 0,001) and 2 50 (p < 0.001), respectively. Thus, the prenatal stress accounted for the maximum changes of the IgA concentration in male rats whereas in females the peak changes occurred as a result of the prenatal and combined stress. On the contrary, the postnatal stress was found to cause the least concentration changes both in males and females. The male rats revealed the highest IgM concentration growth under the prenatal stress (1.72 times, p < 0.001) whereas the postnatal and combined stress resulted in 1.47 times (p < 0.001) and 1.46 times (p < 0.001) growth, respectively. In females, the IgM concentration growth was found to be 1.79 (p < 0.001), 1.67 (p < 0.001) and 1.70 (p < 0.001) times higher in comparison with the controls. The sex difference was noted under the postnatal and combined stress only, the values for the females being by 8. 70 per cent (p < 0.001) and by 11. 30 per cent (p < 0.001) higher, respectively. The male rats revealed the highest IgG concentration growth under the prenatal stress (1.52 times, p < 0.001). Under the postnatal and combined stress, the concentration increased 1.30 (p < 0.001) and 1.29 (p < 0.001) times, respectively. In females, the value increased 1.41(p < 0.001), 1.42 (p < 0 001) and 1.38 times (p < 0.001) as com­ pared with the controls and proved to be virtually irrespective of the way of stress induction. In the aspect of sex difference, under the prenatal stress the growth values were by 10. 20 per cent (p < 0.001) higher in the male rats as compared with the females, while under the postnatal and combined stress the value was found to be higher in the females (by 6.74 per cent, p < 0.001 and 5.24 per cent, p < 0.001, respectively). Thus, the prenatal and postnatal stresses as well as their combined effect result in the immune system tension of young male and female rats. The prenatal stress causing the highest growth of CIC and IgA, IgM and IgG concen­ tration, is the most unfavorable for the males. The females’ immune system is vulnerable to any stress that causes disregulatory changes.

stress, rats males and females, immune system

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«Bulletin of problems biology and medicine» Issue 3 part 2 (111), 2014 year, 126-129 pages, index UDK 612. 017. 1­02:616. 45­001. 1/. 3]­055­092. 9