Immunohistochemical mapping of pro-opiomelanocortin- and pro-dynorphin-derived peptides in the alpaca (Lama pacos) diencephalon
Introduction
Since 2007 knowledge of the chemical neuroanatomy of neuropeptides in South-American camelids has increased considerably. This is because, using immunocytochemical techniques, reports have been made about the distribution of calcitonin gene-related peptide in the alpaca brainstem and diencephalon (Coveñas et al., 2012, de Souza et al., 2008, Marcos et al., 2011, Marcos et al., 2013), the presence of somatostatin-28 (1–12) in the alpaca diencephalon (Coveñas et al., 2011) and the distribution of fibres and cell bodies containing neurotensin or leucine-enkephalin in the alpaca brainstem (de Souza et al., 2007, de Souza et al., 2014). Moreover, the colocalization of calcitonin gene-related peptide and somatostatin-28 (1–12) with tyrosine hydroxylase has been also reported in the alpaca brainstem and diencephalon respectively (Marcos et al., 2011, Marcos et al., 2013). In all cases, the studies were carried out in control animals (alpacas not treated with colchicine). To date, in the alpaca diencephalon, a region of the central nervous system involved in important functional mechanisms, the mapping of only two neuropeptides (calcitonin gene-related peptide and somatostatin-28 (1–12)) has been carried out (Coveñas et al., 2011, Coveñas et al., 2012, Marcos et al., 2013). Thus, no studies addressing the presence of adrenocorticotropin hormone-, alpha-melanocyte-stimulating hormone- and opioid peptide-immunoreactive structures in the alpaca diencephalon have been performed. Currently, the only opioid peptide mapped in the alpaca is leucine-enkephalin, and then only in the brainstem (de Souza et al., 2007).
Opioid peptides can be classified in three families according to their precursors: (1) beta-endorphin, alpha- and beta-melanocyte-stimulating hormone, adrenocorticotropin hormone, methionine-enkephalin, and alpha-, and gamma-endorphin are produced from pro-opiomelanocortin; (2) leucine-enkephalin, methionine-enkephalin, methionine-enkephalin-Arg-Gly-Leu and methionine-enkephalin-Arg-Phe from pro-enkephalin; and (3) alpha-neo-endorphin, leucine-enkephalin, dynorphin A and dynorphin B from pro-dynorphin. Our main aim in this work was to study and compare for the first time the distribution of the pro-opiomelanocortin and pro-dynorphin systems in the alpaca diencephalon. Thus, using an immunocytochemical technique we studied the distribution of fibres and cell bodies containing beta-endorphin (1–27), alpha-melanocyte-stimulating hormone and adrenocorticotropin hormone (exclusively produced from pro-opiomelanocortin), as well as the distribution of immunoreactive structures containing alpha-neo-endorphin (exclusively produced from pro-dynorphin). In addition, the distribution of leucine-enkephalin (derived from pro-enkephalin and from pro-dynorphin) was also studied, as the mapping of this opioid peptide has been reported previously in the alpaca brainstem (de Souza et al., 2007), but not in the alpaca diencephalon. A further aim was to compare the distribution of adrenocorticotropin hormone/alpha-melanocyte-stimulating hormone and the three opioid peptides studied here with that previously reported for calcitonin gene-related peptide/somatostatin-28 (1–12), in order to know whether a close anatomical relationship occurs or not among these hormones and peptides in the alpaca diencephalon (Coveñas et al., 2011, Coveñas et al., 2012). Another aim was to compare the distribution of the five peptides detected here with those described previously for the same peptides in the mammalian diencephalon. The peptides studied play important roles in the mammalian central nervous system. For example, they have been implicated in stress, sexual and feeding mechanisms, neuroendocrine, temperature and cardiovascular regulation, aggressive and defensive behaviour, and in aging (Coveñas et al., 2007). Alpacas are able to live at sea level and at more than 5000 m altitude, making this animal an interesting but relatively unknown species that could reveal the existence of special, unique regulatory mechanisms. In the future, the neuroanatomical findings from the alpaca described here should serve to better understand the involvement of adrenocorticotropin hormone/alpha-melanocyte-stimulating hormone and opioid peptides as regards the adaptation of the species to vastly different altitudes and their reproductive and social behaviour. This is important owing to the economic importance of the wool of these animals in some South American countries.
Section snippets
Animals and tissue preparation
The experimental design, protocols, and procedures of this work were performed under the principles of laboratory animal care and under the guidelines of the ethics and legal recommendations of Peruvian and Spanish legislation. This work was also approved by the research commission of the Cayetano Heredia Peruvian University (Lima, Peru). Four male adult alpacas (Lama pacos) (Huacaya breed) (5–8 years; 70–80 kg) were obtained from the Cayetano Heredia Peruvian University (Faculty of Veterinary
General considerations
Table 1 and Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 show the distribution and density of immunoreactive fibres and cell bodies containing ACTH/alpha-melanocyte-stimulating hormone and the opioid peptides studied in the alpaca diencephalon. In general, for each neuropeptide the distribution of the immunoreactive structures (fibres and cell bodies), as well as the density of such structures, were quite similar in the four diencephalons studied.
In general, cell bodies containing the peptides were
Pro-opiomelanocortin- and pro-dynorphin-derived peptides in the alpaca diencephalon
This is the first report describing the distribution of fibres and cell bodies containing opioid peptides and the non-opioid peptides ACTH and alpha-melanocyte-stimulating hormone in the alpaca diencephalon. Perikarya containing alpha-MSH or alpha-NE showed a more widespread distribution than those containing leu-enk or beta-endorphin (1–27). Cell bodies containing exclusively pro-dynorphin-derived peptides were observed in the dorsal hypothalamic area and those containing only
Acknowledgements
The authors thank Professor Gérard Tramu (University of Bordeaux I, France) for kindly providing the first antisera and N. Skinner (University of Salamanca, Spain) for stylistic revision of the English text. This work has been supported by the Ministerio de Educación y Ciencia (BFU2005-02241/BFI), Spain and the Ministerio de Ciencia e Innovación (BFU2008-03369/BFI), Spain and by the CONCYTEC: PROCYT project 2006, Peru.
References (35)
- et al.
Mapping of alpha-melanocyte-stimulating hormone-like immunoreactivity in the cat diencephalon
Peptides
(1996) - et al.
An immunocytochemical mapping of beta-endorphin (1–27) in the cat diencephalon
Neuropeptides
(1996) - et al.
An immunocytochemical mapping of ACTH/CLIP in the cat diencephalon
J. Chem. Neuroanat.
(1996) - et al.
Mapping of somatostatin-28 (1–12) in the alpaca diencephalon
J. Chem. Neuroanat.
(2011) - et al.
Mapping of CGRP in the alpaca diencephalon
J. Chem. Neuroanat.
(2012) - et al.
Somatostatin-28 (1–12)-like immunoreactivity in the cat diencephalon
Neuropeptides
(1991) - et al.
Mapping of CGRP in the alpaca (Lama pacos) brainstem
J. Chem. Neuroanat.
(2008) - et al.
Regional distribution of methionine-enkephalin- and beta-endorphin-like immunoreactivity in human brain and pituitary
Brain Res.
(1979) - et al.
ACTH-immunoreactive neurons and their projections in the cat forebrain
Peptides
(1986) - et al.
CGRP microinjection into the ventromedial or dorsomedial hypothalamic nucleus activates heat production
Brain Res.
(1999)
Immunohistochemical mapping of enkephalins, NPY, CGRP, and GRP in the cat amygdala
Peptides
Mapping of tyrosine hydroxylase in the alpaca (Lama pacos) brainstem and colocalization with CGRP
J. Chem. Neuroanat.
Mapping of tyrosine hydroxylase in the diencephalon of alpaca (Lama pacos) and co-distribution with somatostatin-28 (1–12)
J. Chem. Neuroanat.
Neurons containing alpha-melanocyte stimulating hormone and beta-endorphin immunoreactivity in the cat hypothalamus
Peptides
Stress, reproduction, and adrenocortical modulation in amphibians and reptiles
Horm. Behav.
Distribution of ACTH immunoreactivity in the diencephalon and the brainstem of the dog
J. Chem. Neuroanat.
The distribution pattern of adrenocorticotropin-like immunoreactivity in the cat central nervous system
Neurosci. Lett.
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2019, Vitamins and HormonesCitation Excerpt :It is also known that the ACTH-immunoreactive perikarya located in the nucleus of the solitary tract send projections to the spinal cord, nucleus reticularis gigantocellularis, and A1 cell group (Jégou et al., 2013) and that those located in the arcuate nucleus send projections to the diencephalon (e.g., nucleus ventromedialis hypothalami, nucleus paraventricularis thalami, perifornical region) and locus coeruleus (Kitahama, Sakai, & Jouvet, 1984; Kitahama et al., 1986). ACTH-immunoreactive fibers are widely distributed throughout the mammalian central nervous system (e.g., amygdala, thalamus, hypothalamus, brainstem, spinal cord) (Manso et al., 2014; Palkovits, 1988). For example, ACTH-immunoreactive fibers have been observed in regions of the central nervous system in which clusters of serotonergic (raphe nuclei), noradrenergic (Kölliker-Fuse/parabrachial nuclei, locus coeruleus) and dopaminergic (ventral tegmental area) neurons are located (Pesini et al., 2004).
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2016, PeptidesCitation Excerpt :Endomorphin 2-immunopositive neurons were localized in the myenteric plexus of the rat colon [483]. Immunohistochemical mapping in the alpaca diencephalon revealed POMC reactivity in the arcuate, anterior, lateral, ventro-medial and supraoptic hypothalamic nuclei and PDYN reactivity in the arcuate, dorsal, lateral, paraventricular, ventromedial and supraoptice hypothalamic nuclei [554]. Pharmacological MRI in awake nonhuman primates revealed buprenorphine activation in thalamus, striatum, and frontal and cingulate cortices [914].
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