Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Prenatal Stress (PS) appears to imprint the organizing brain during critical stages of prenatal development and it seems that these effects remain with the organims, modifying the input, processing and output of behaviors related to relevant stimuli. These effects on the behavior and physiology of rodents has been demonstrated to occur via modifications of brain sexual differentation. The Accesory Olfactory Bulb is a sexually dimorphic structure belonging to the Vomeronasal System (VNS). This chemosensory system is directly implicated in the expression of natural and induced maternal behavior in rats. In this study we investigate whether the PS treatment may cause a long-lasting effect on the induction of maternal behavior and the AOB mitral cells activation in female rats. We have used Fos immunocytochemical visualization of the nuclear protein product Fos of the immediate-early gene c-fos as a marker of neuronal activity. Materials and methods: Two groups of Wistar female rats were formed. Control (CF) and prenatally stressed rats (PS-3). Stress procedure, applied to the mothers of the PS-3 group, consisted in three daily sessions of 45 minutes (restrain, heat and light) during the last week of pregnancy. At the age of 90 days, both groups (CF and PS-3) were tested for induced MB, using the MBR procedure during 12 consecutive days. Results: a) Behavioral: The percentage of PS-3 rats that became maternal was significantly lower than that of CF group, showing poorest nest building scores too. B) Immunocytochemical: The number of c-Fos expressing neurons in AOB mitral cell layer was greater in the CF maternal females than in CF non maternal or PS-3 females. No significant differences were found between Control-non sensitized animals and Prenatally Stressed females. These data suggest that MB induced by continous pup stimuli exposure, correlates with Fos protein expression in AOB. In contrast, in this structure lower c-fos expression in PS-3 females corresponds with no MB, as well as in the Control non-maternal females. We may conclude that Fos protein levels are behavior dependent. That is, Fos production increases in the AOB of maternally behaving female rats, whereas low levels of Fos production is expressed in non-maternal animals, independently of treatment. This study has been supported by a DGICYT grant # PB96.0107-C03-02

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Presentation Number SArodríguez-martín0816
Keywords: Materna Behavior, Access. Olf. Bulb, Fos, Prenatal Stress