ReviewNeural and hormonal mechanisms of reproductive-related arousal in fishes
Research Highlights
► Teleosts and elasmobranchs are powerful models to investigate mechanisms of brain arousal. ► The output of the core–paracore brain region is integrated with sensory and motor systems. ► Neurochemicals and neural circuits which underlie arousal are evolutionarily conserved.
Section snippets
Introduction: Evolutionarily conserved neurochemicals and pathways of sexual arousal
Mong et al. (2003) comment that “high arousal is reflected by high sensory responsiveness, high motor activity, and high emotional reactivity.” Ultimately, changes in levels of arousal of any one sensory or motor system depend on some form of modulatory input originating from what Nieuwenhuys et al. (1988) define as the neurochemically rich “core” and “paracore” that together form a neuroendocrine “axis” in the brain. Core regions, like the preoptic area (POA), lie adjacent to the brain's
Connectivity, neurochemistry and function of the POA/anterior hypothalamus
The POA and anterior hypothalamus, neurochemical “core” areas essential for the control of reproductive physiology and hence behavior in all vertebrates, show a highly conserved pattern of anatomical organization (Butler and Hodos, 2005, Meek and Nieuwenhuys, 1998). The POA and anterior hypothalamus can be viewed as one functional unit, the POA, because of their shared developmental origin (Puelles, 2001) and obvious homologies between neuropeptide-containing cell groups in the POA of teleosts
Brain arousal and reproductive behavior in vocal fishes
Vocal teleost fish species have a long history as models for studying the neural basis of behavior due to their simple, stereotyped, and easily quantified behaviors that are controlled by a discrete population of neurons whose anatomical and physiological properties are well defined (Bass and Zakon, 2005). These fish have also provided excellent models to study how steroids and neuropeptides rapidly modulate plasticity in neural circuits controlling behavior (Bass and Remage-Healey, 2008,
Neural substrates for sexual arousal and reproductive behavior in elasmobranch fishes
Elasmobranch fishes are an important group for comparative and evolutionary studies, as they belong to the oldest lineage of extant jawed vertebrates (Chondrichthyes, see Fig. 1), and serve as an outgroup to bony vertebrates (actinopterygians and tetrapods) and may therefore provide further insights into the ancestral vertebrate condition in brain and behavior. In many respects, their reproductive physiology (Maruska and Gelsleichter, 2010) and, in some cases, chemical neuroanatomy (below) is
Concluding comments
Interdisciplinary approaches combining behavioral endocrinology with molecular neuroanatomy (location and abundance of steroid synthesizing enzymes and receptors, peptidergic pathways) and neurophysiology have established both teleosts and elasmobranch fishes as powerful model systems to investigate cellular mechanisms of brain arousal, especially in the context of reproduction. The output of a highly conserved core–paracore region, inclusive of the POA-anterior hypothalamus and brainstem cell
Acknowledgments
Support during the preparation of this manuscript was provided by Brooklyn College and the CUNY Research Foundation to PMF and NIH (DC00092) and NSF (IOB0516748) grants to AHB.
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