Neuronal and glial localization of α_2A‐adrenoceptors in the adult zebrafish (Danio rerio) brain

Abstract

The alpha(2A)-adrenoceptor (AR) subtype, a G protein-coupled receptor located both pre- and postsynaptically, mediates adrenaline/noradrenaline functions. The present study aimed to determine the alpha(2A)-AR distribution in the adult zebrafish (Danio rerio) brain by means of immunocytochemistry. Detailed mapping showed labeling of alpha(2A)-ARs, in neuropil, neuronal somata and fibers, glial processes, and blood vessels. A high density of alpha(2A)-AR immunoreactivity was found in the ventral telencephalic area, preoptic, pretectal, hypothalamic areas, torus semicircularis, oculomotor nucleus (NIII), locus coreruleus (LC), medial raphe, medial octavolateralis nucleus (MON), magnocellular octaval nucleus (MaON), reticular formation (SRF, IMRF, IRF), rhombencephalic nerves and roots (DV, V, VII, VIII, X), and cerebellar Purkinje cell layer. Moderate levels of alpha(2A)-ARs were observed in the medial and central zone nuclei of dorsal telencephalic area, in the periventricular gray zone of optic tectum, in the dorsomedial part of optic tectum layers, and in the molecular and granular layers of all cerebellum subdivisions. Glial processes were found to express alpha(2A)-ARs in rhombencephalon, intermingled with neuronal fibers. Medium-sized neurons were labeled in telencephalic, diencephalic, and mesencephlic areas, whereas densely labeled large neurons were found in rhombencephalon, locus coeruleus, reticular formation, oculomotor area, medial octavolateralis and magnocellular octaval nuclei, and Purkinje cell somata. The functional role of alpha(2A)-ARs on neurons and glial processes is not known at present; however, their strong relation to the ventricular system, somatosensory nuclei, and nerves supports a possible regulatory role of alpha(2A)-ARs in autonomic functions, nerve output, and sensory integration in adult zebrafish brain.

Unmyelinated nerve fibers in the human dental pulp express markers for myelinated fibers and show sodium channel accumulations

“…This antibody has been used in many previous studies [58-61] and the staining pattern seen in the current study is consistent with other studies that used the same or other TH antibodies [62,63]. …”

A High-Throughput Fluorescence-Based Assay System for Appetite-Regulating Gene and Drug Screening

“…A high dose of sibutramine (10 µM) induced htr1aa and htr1ab expression, suggesting hypersensitivity and activation of 5-HT signaling, possibly increasing the anorexic effects of sibutramine. The adrenergic system of zebrafish has been well characterized by many researchers, and α2a-adrenoceptors have been shown to be expressed in the hypothalamus [64]. These findings suggest the involvement of adrenergic signaling in the satiety center of the zebrafish brain, similar to that seen in mammals [65].…”

Sexual dimorphisms in swimming behavior, cerebral metabolic activity and adrenoceptors in adult zebrafish (Danio rerio)

“…To label the α 2 -ARs and β-ARs, in vitro autoradiography was applied [34,35,36], using the antagonists [ 3 H]-RX821002 (for α 2 -AR; 54Ci/mol, Amersham, UK) and Following incubation, free radioligand was removed by two washes in ice-cold TrisHCl buffer (5 and 10 minutes), and then sections were dried in a cold air stream.…”

“…Indeed, adrenoceptors are known to display sex dimorphic pattern in brain areas of avian [31,32] and mammalian [33] species. Recent evidence suggests that, zebrafish brain α 2 -and β-ARs [34,35] share similar characteristics with other teleosts [36], amphibians [37], birds [38,39] and mammals [40,41].…”