Mapping of tyrosine hydroxylase in the diencephalon of alpaca (Lama pacos) and co-distribution with somatostatin-28 (1-12) P. Marcos a, *, M.M. Arroyo-Jime ´ nez a , G. Lozano a , J. Gonza ´ lez-Fuentes a , M.J. Lagartos-Donate a , L.A. Aguilar b , R. Coven ˜as c a Laboratorio de Neuroanatomı´a Humana, Centro Regional de Investigaciones Biome ´dicas (CRIB), Universidad de Castilla-La Mancha, Facultad de Medicina, Avenida de Almansa 14, 02006 Albacete, Spain b Peruvian University Cayetano Heredia, School of Medicine ‘‘Alberto Hurtado’’, Lima, Peru c Universidad de Salamanca, Institute of Neurosciences of Castilla and Leo ´n (INCYL), Laboratory of Neuroanatomy of the Peptidergic Systems (Lab. 14), Salamanca, Spain 1. Introduction Knowledge of the distribution of catecholamines and other neuroactive substances in the brain of different mammalian species has been available for some years (for a review, see Smeets and Gonza ´ lez, 2000). However, despite the large number of studies performed on the rodent brain (Manger et al., 2008), in many species there is a lack of sufficient data concerning the location of these cellular groups in this organ. One of these species is the alpaca (Lama pacos), an ungulate included in the family of camelidae and a member of the order Artiodactyla. Although this species has been studied because of its importance for the economy of South American countries such as Peru owing to the high quality of the wool (De Souza et al., 2007), such studies have mainly focused on physiological reproductive aspects and hormonal mechanisms (for review, see De Souza et al., 2008). These animals have a unique physiology, because they are able to live at altitudes ranging from sea level to more than 5000 m and have a long neck (similar to other camelidae members), suggesting interesting and specific regulatory mechanisms, for example those Journal of Chemical Neuroanatomy 50–51 (2013) 66–74 A R T I C L E I N F O Article history: Received 25 January 2013 Received in revised form 21 February 2013 Accepted 21 February 2013 Available online 6 March 2013 Keywords: Catecholaminergic cell groups Diencephalon Hypothalamus Somatostatin Artiodactyla Immunohistochemistry A B S T R A C T Based on previous work describing the distribution of somatostatin-28 (1-12) in the male alpaca (Lama pacos) diencephalon, and owing to the well known interactions between this peptide and the catecholaminergic system, the aims of this work are (1) to describe the distribution of putative catecholaminergic cell groups in the alpaca diencephalon and (2) to study the possible morphological basis of the interactions between these substances in the diencephalon of the alpaca by using double immunohistochemistry methods. Thus, the distribution of catecholaminergic cell groups in the alpaca diencephalon agrees with that previously described in the diencephalon of other mammalian species of the same order: the A11, A12, A13, A14 and A15d cell groups have been identified; however, we have observed an additional hitherto undescribed cell group containing tyrosine hydroxylase in the medial habenula. In addition, double-labelling procedures did not reveal neurons containing tyrosine hydroxylase and somatostatin, suggesting that the hypothalamic interactions between catecholamines and somatostatin at intra-cellular level must be carried out by a somatostatin molecule other than fragment (1-12). Otherwise, the overlapping distribution patterns of these substances would suggest some interconnections between groups of chemospecific neurons. These results could be the starting point for future studies on hypothalamic functions in alpacas, for example those concerning reproductive control, since other physiological studies have suggested that this species could have different regulatory mechanisms from other mammalian species. Our results support the Manger hypothesis that the same nuclear complement of neural systems exists in the brain of species of the same order. ß 2013 Elsevier B.V. All rights reserved. Abbreviations: 3V, third ventricle; A9, substantia nigra; A10, ventral tegmental area; A11, caudal diencephalic group; A12, tuberal cell group; A13, zona incerta; A14, rostral periventricular nucleus; A15d?, incipient anterior hypothalamic group, dorsal division?; A15v, anterior hypothalamic group, ventral division; Arc, arcuate nucleus; Ci, capsula interna; D6?, D6-type cells?; Fx, fornix; LH, lateral hypothalamic area; LHb, lateral habenular nucleus; LM, lateral mammillary nucleus; MHb, medial habenular nucleus; Opt, optic tract; PC, cerebral peduncle; PeVH, periventricular hypothalamic nucleus; PVH, paraventricular hypothalamic nucleus; Sch, supra- chiasmatic nucleus; so, supraoptic nucleus; VMH, ventromedial hypothalamic nucleus. * Corresponding author. Tel.: +34 967599200; fax: +34 967599340. E-mail address: Pilar.Marcos@uclm.es (P. Marcos). Contents lists available at SciVerse ScienceDirect Journal of Chemical Neuroanatomy jo ur n al ho mep ag e: www .elsevier .c om /lo cate/jc h emn eu 0891-0618/$ – see front matter ß 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jchemneu.2013.02.006