Methods to Assess the Role of Neurogenesis in Reproductive Behaviors of Birds, Rats, and Sheep

Abstract

Reproduction represents one of the most important biological events for the organism due to its relevance in perpetuating life. It allows the production of offspring with similar characteristics to the progenitor. The behavioral events of reproduction comprise several changes that prepare the organisms and favor the display of specific behaviors. Reproduction starts with the localization and selection of a possible partner, and this specific moment requires the detection of chemosensory cues that guides their attention and behavior. After the adequate partner is selected, the sexual interaction takes place, usually regulated by females. If pregnancy happens, a series of changes and adaptations occurs within the brain that prepares the mother for the future interaction with the offspring. After delivery, interaction with the offspring during early postpartum along with the pregnancy adaptations of the new mother allows the display of a complex set of parental behaviors that facilitate the care and survival of the newborn. During all these reproductive steps, several adaptations occur within the brain that prepare the organism for its current needs and, in some cases, maintain the changes until the next reproductive episode. The aim of the present chapter is to discuss one of the most complex plastic adaptations, namely adult neurogenesis that occurs in the brain and accompanies the different steps of reproduction in life. From partner attraction and selection through sexual interaction to the parental care of the offspring, we selected three different species in which evidence has shown that neurogenesis plays an important role. We will describe how in songbirds, neurons recently incorporated to the high-vocal center are necessary for the female attraction by facilitating a new singing repertoire of the male each reproductive season. In rats, from the first sexual behavior encounter, neurogenesis in the olfactory bulb is stimulated allowing a facilitation of the following interactions. The deployment of maternal behavior in sheep requires an early and highly specialized odor recognition of the offspring by the mother in which newly born olfactory bulb neurons participate. Additionally, in this chapter we overview two of the most used techniques to visualize and study adult neurogenesis, the use of endogenous and exogenous markers revealed by immunostainings and neuronal precursor labeling by electroporation.