Abstract

INTRODUCTION

BRAIN REGIONS AND MATERNAL BEHAVIOR

FOS RESEARCH

CONCLUSIONS

REFERENCES

Discussion
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Immediate early genes (IEGs) are activated by extracellular signals, and their protein products serve as transcription factors which influence the expression of late-responding genes. Activation of IEGs and the subsequent expression of their protein products has been used as a measure of cellular activation. The fos family of IEGs includes cfos and fos B. We have used Fos immunocytochemistry to explore the neural basis of maternal behavior in rats. Female rats that are engaged in maternal behavior show increased expression of both cFos and Fos B in the medial preoptic area (MPOA) and ventral part of the bed nucleus of the stria terminalis (vBST), suggesting that the MPOA/vBST is activated during maternal behavior and supporting other work suggesting the positive involvement of these areas in maternal behavior. Although both cFos and Fos B are expressed in MPOA/vBST neurons during maternal behavior, their temporal course of expression differs, suggesting that they may play different roles. A recent double-labeling study, which combined Fos immunocytochemistry with retrograde neural-tract tracing, has uncovered neural sites to which MPOA/vBST Fos-expressing neurons project, suggesting neural circuits involved in maternal behavior control. Unlike postpartum females, virgin female rats do not show maternal behavior when first exposed to pups. Evidence suggests that unless females are primed with the hormones of pregnancy, novel pup stimuli act to inhibit maternal behavior. A recent series of studies in our laboratory, using Fos immunocytochemistry, has mapped the neural regions which are activated when virgin females are initially exposed to pups, suggesting neural regions which may be involved in inhibiting maternal behavior.

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Presentation Number SAnuman0822
Keywords: maternal behavior, fos, preoptic area