Meeting Abstract
Studies across vertebrate lineages show that galanin (gal) is a neuropeptide that plays an important role in regulating both reproductive and parental behavior. We have found that gal transcript expression varies across reproductive behavioral state in a fish with alternative reproductive tactics, the plainfin midshipman (Porichthys notatus). Male midshipman have two morphs that reproduce either through defending nests and courting females (type I males), or cuckolding at the nest of courting males (type I or type II males). Here, we used immunohistochemistry and an antibody specific to midshipman gal to identify cells in the midshipman brain expressing gal peptide and describe the sites of their projections. Gal-immunoreactive (ir) cell bodies occurred in the anterior and posterior parvocellular preoptic area (POA), with dense projections of gal-ir processes into regions strongly implicated in regulating social behavior, including the ventral nucleus of the ventral telencephalon (proposed homology to mammalian septum) and midbrain periaqueductal grey (PAG); and vocalization, including the supracommissural nucleus of the ventral telencephalon (proposed homology to basal amygdala) and PAG. Dense gal-ir processes and putative terminals were also observed in sensory processing sites for vision in the pretectum and tectum; and for audition and/or lateral line in the forebrain, midbrain and hindbrain. Label was generally robust throughout the midbrain tegmentum and hindbrain reticular formation that included the region of premotor neurons of the vocal central pattern generator. Finally, we used double-labelling with pS6, a protein marker of neuron activity, to identify changes in gal-ir neuron activity in the POA during spawning in courting and cuckolding males. Research support from NSF IOS 1656664 and Cornell University.
