title: Local vasotocin modulation of the pacemaker nucleus resembles distinct electric behaviors in two species of weakly electric fish.
abstract: The neural bases of social behavior diversity in vertebrates have evolved in close association with hypothalamic neuropeptides. In particular, arginine-vasotocin (AVT) is a key integrator underlying differences in behavior across vertebrate taxa. Behavioral displays in weakly electric fish are channeled through specific patterns in their electric organ discharges (EODs), whose rate is ultimately controlled by a medullary pacemaker nucleus (PN). We first explored interspecific differences in the role of AVT as modulator of electric behavior in terms of EOD rate between the solitary Gymnotus omarorum and the gregarious Brachyhypopomus gauderio. In both species, AVT IP injection (10μg/gbw) caused a progressive increase of EOD rate of about 30%, which was persistent in B. gauderio, and attenuated after 30min in G. omarorum. Secondly, we demonstrated by in vitro electrophysiological experiments that these behavioral differences can be accounted by dissimilar effects of AVT upon the PN in itself. AVT administration (1μM) to the perfusion bath of brainstem slices containing the PN produced a small and transient increase of PN activity rate in G. omarorum vs the larger and persistent increase previously reported in B. gauderio. We also identified AVT neurons, for the first time in electric fish, using immunohistochemistry techniques and confirmed the presence of hindbrain AVT projections close to the PN that might constitute the anatomical substrate for AVT influences on PN activity. Taken together, our data reinforce the view of the PN as an extremely plastic medullary central pattern generator that not only responds to higher influences to adapt its function to diverse contexts, but also is able to intrinsically shape its response to neuropeptide actions, thus adding a hindbrain target level to the complexity of the global integration of central neuromodulation of electric behavior.
authors.affiliation: Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, 11600 Montevideo, Uruguay. Electronic address: rperrone@iibce.edu.uy.
authors.forename: Rossana
authors.initials: R
authors.lastname: Perrone
authors.affiliation: Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, 11600 Montevideo, Uruguay; Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay. Electronic address: amigliaro@fcien.edu.uy.
authors.forename: Adriana
authors.initials: A
authors.lastname: Migliaro
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, 11800 Montevideo, Uruguay. Electronic address: vcomas@fmed.edu.uy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Comas
authors.affiliation: Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, 11600 Montevideo, Uruguay. Electronic address: lquintana@iibce.edu.uy.
authors.forename: Laura
authors.initials: L
authors.lastname: Quintana
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, 11800 Montevideo, Uruguay. Electronic address: mborde@fmed.edu.uy.
authors.forename: Michel
authors.initials: M
authors.lastname: Borde
authors.affiliation: Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, 11600 Montevideo, Uruguay; Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay. Electronic address: asilva@iibce.edu.uy.
authors.forename: Ana
authors.initials: A
authors.lastname: Silva
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001683:Biological Clocks / Q000502:physiology*; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000294:innervation / Q000502:physiology; D055724:Electrophysiological Phenomena / Q000502:physiology; D007031:Hypothalamus / Q000502:physiology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D012249:Rhombencephalon / Q000378:metabolism / Q000502:physiology; D013045:Species Specificity; D014668:Vasotocin / Q000502:physiology*
chemical_list: D014668:Vasotocin
keywords: AVT; Brachyhypopomus gauderio; EOD rate; Gymnotus omarorum; Hypothalamic neuropeptides; Neuromodulation