Neuroanatomical distribution of vasotocin in a urodele amphibian (Taricha granulosa) revealed by immunohistochemical and in situ hybridization techniques

Abstract

Immunohistochemical and in situ hybridization techniques were used to investigate the neuroanatomical distribution of arginine vasotocin-like systems in the roughskin newt (Taricha granulosa). Vasotocin-like-immunoreactive neuronal cell bodies were identified that, based on topographical position, most likely, are homologous to groups of vasopressin-immunoreactive neuronal cell bodies described in mammals, including those in the bed nucleus of the stria terminalis, medial amygdala, basal septal region, magnocellular basal forebrain-including the horizontal limb of the diagonal band of Broca, paraventricular and supraoptic nuclei, suprachiasmatic nucleus, and dorsomedial hypothalamic nucleus. Several additional vasotocin-like-immunoreactive cell groups were observed in the forebrain and brainstem regions; these observations are compared with previous studies of vasotocin- and vasopressin-like systems in vertebrates. Arginine vasotocin-like-immunoreactive fibers and presumed terminals also were widely distributed with high densities in the basal limbic forebrain, the ventral preoptic and hypothalamic regions, and the brainstem ventromedial tegmentum. Based on in situ hybridization studies with synthetic oligonucleotide probes for vasotocin and the related neuropeptide mesotocin, as well as double-labeling studies with combined immunohistochemistry and in situ hybridization, we conclude that the vasotocin immunohistochemical procedures used identify vasotocin-like, but not mesotocin-like, elements in the brain of T. granulosa. The distribution of arginine vasotocin-like systems in T. granulosa is greater than the distribution previously reported for any other single vertebrate species; however, it is consistent with an emerging pattern of distribution of vasotocin- and vasopressin-like peptides in vertebrates. Complexity in the vasotocinergic system adds further support to the conclusion that this peptide regulates multiple neurophysiological and neuroendocrinological functions.

Localization of three types of arginine vasotocin receptors in the brain and pituitary of the newt Cynops pyrrhogaster

“…The anatomical nomenclature as given in Table 2 is based on the studies of Smeets (1992a, 1992b), Lowry et al (1997), Lewis et al (2005), and Hollis et al (2006).…”

“…3k, 5m) of the mesencephalon Table 2 Distribution and relative abundance of three types of AVT receptor mRNAs and immunoreactive cells in the brain and pituitary of the newt (++ intense signal, + moderate signal, -no immunoreactivity or no mRNA hybridization signal). Anatomical nomenclature is according to Smeets (1992a, 1992b), Lowry et al (1997), Lewis et al (2005), and Hollis et al (2006) Structures…”

The vertebrate social behavior network: Evolutionary themes and variations

“…The BST of reptiles and amphibians is not differentiated into medial and lateral subdivisions, but a portion of the nucleus contains AVT neurons (Stoll and Voorn, 1985;Smeets et al, 1990;Lowry et al, 1997;Marin et al, 1998), as found for the medial BST of most mammals and birds (De Vries et al, 1985;Caffe et al, 1989;Aste et al, 1998). 3 The POA of fish incorporates peptidergic neuron groups that are homologous to anterior hypothalamic populations in tetrapods (supraoptic and paraventricular nuclei) (Moore and Lowry, 1998).…”

Pheromones enhance somatosensory processing in newt brains through a vasotocin-dependent mechanism

“…There are VT terminals (Lowry et al 1997) and receptors (Boyd & Moore 1991;Lewis et al 2005) in the newt medulla, although the source of those projections and the circuits through which olfactory stimuli activate them have not yet been identified. Additionally, although we did not characterize individual neuronal responses as did Rose et al (1995), and thus cannot say whether individual neurons are firing more or previously unresponsive neurons are being recruited in response to FSW, our present results are consistent with what they observed when exogenous VT was applied to the medulla, which was that neuronal responses to somatosensory stimuli typically increased.…”