title: Serotonergic fibers distribution in the midline and intralaminar thalamic nuclei in the rock cavy (Kerodon rupestris).
abstract: The thalamic midline/intralaminar complex is part of the higher-order thalamus, which receives little sensory input, and instead forms extensive cortico-thalamo-cortical pathways. The midline thalamic nuclei connect with the medial prefrontal cortex and the medial temporal lobe. On the other hand, the intralaminar nuclei connect with the fronto-parietal cortex. Taking into account this connectivity pattern, it is not surprising that the midline/intralaminar complex has been implicated in a broad variety of cognitive functions, including memory process, attention and orientation, and also reward-based behavior. Serotonin (5-HT) is a neurotransmitter that exerts different post-synaptic roles. Serotonergic neurons are almost entirely restricted to the raphe nuclei and the 5-HT fibers are distributed widely throughout the brain, including the midline/intralaminar complex. The present study comprises a detailed description of the morphologic features and semiquantitative analysis of 5-HT fibers distribution in the midline/intralaminar complex in the rock cavy, a typical rodent of the Northeast region of Brazil, which has been used by our group as an anatomical model to expand the comprehension about phylogeny on the nervous system. The 5-HT fibers in the midline/intralaminar nuclei of the rock cavy were classified into three distinct categories: (1) beaded fibers, which are relatively fine and endowed with large varicosities; (2) fine fibers, with thin axons and small varicosities uniformly distributed in whole axon; and (3) stem axons, showing thick non-varicose axons. Moreover, the density of 5-HT fibers is variable among the analyzed nuclei. On the basis of this diversity of the morphological fibers and the differential profile of optical density among the midline/intralaminar nuclei of the rock cavy, we conclude that the serotonergic system uses a diverse morphologic apparatus to exert a large functional repertory in the midline/intralaminar thalamic nuclei.
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Alane de Medeiros
authors.initials: Ade M
authors.lastname: Silva
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Melquisedec Abiaré Dantas
authors.initials: MA
authors.lastname: de Santana
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Paulo Leonardo Araújo de Góis
authors.initials: PL
authors.lastname: Morais
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Twyla Barros
authors.initials: TB
authors.lastname: de Sousa
authors.affiliation: Department of Physiology/Laboratory of Neurochemical Studies, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Rovena Clara Galvão Januário
authors.initials: RC
authors.lastname: Engelberth
authors.affiliation: Department of Physiology/Laboratory of Neurochemical Studies, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Eudes Euler de Souza
authors.initials: EE
authors.lastname: Lucena
authors.affiliation: Department of Physiology/Memory Studies Laboratory, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Clarissa Loureiro das Chagas
authors.initials: CL
authors.lastname: Campêlo
authors.affiliation: Department of Physiology/Laboratory of Neurochemical Studies, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Jeferson Sousa
authors.initials: JS
authors.lastname: Cavalcante
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Judney Cley
authors.initials: JC
authors.lastname: Cavalcante
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
authors.forename: Miriam Stela Maris de Oliveira
authors.initials: MS
authors.lastname: Costa
authors.affiliation: Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil. Electronic address: expeditojr@cb.ufrn.br.
authors.forename: Expedito Silva
authors.initials: ES
authors.lastname: do Nascimento
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D006168:Guinea Pigs; D020646:Intralaminar Thalamic Nuclei / Q000033:anatomy & histology*; D020644:Midline Thalamic Nuclei / Q000033:anatomy & histology*; D009412:Nerve Fibers / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin
keywords: Fiber morphology; Midline/intralaminar nuclei; Optical density; Rock cavy; Serotonergic system; Thalamus