Neurohypophysial Hormones Associated with Osmotic Challenges in the Brain and Pituitary of the Euryhaline Black Porgy, Acanthopagrus schlegelii.

Adimoolam Aruna,Ganesan Nagarajan,Chien-Ju Lin,Ching-Fong Chang

doi:10.3390/cells10113086

Abstract

Our study showed differential expression of the arginine vasotocin (avt)/isotocin (it) in the brain and pituitary gland of the euryhaline black porgy (Acanthopagrus schlegelii) during osmotic stress. A decrease in serum osmolality and increased cortisol levels were observed after acute transfer from seawater (SW) to freshwater (FW). The increased expressions of avt, avt receptor (avtr: v1a), and isotocin receptor (itr: itr1) transcripts on day 1 and it and itr transcripts on days 7 and 30 were found in the brains and pituitary glands of FW fish. Increased levels of avt mRNA in the diencephalon and avtr mRNA in the pituitary together with serum cortisol on day 1 of FW exposure indicated activation of the hypothalamic–pituitary–interrenal (HPI) axis. The expression levels of avtr and itr after FW transfer were increased in the pituitary on days 7 and 30. Furthermore, in situ hybridization demonstrated spatially differential expression of avt and itr transcripts in nucleus preopticus parvocellularis of pars gigantocellularis (PMgc), magnocellularis (PMmc), and parvocellularis (PMpc) of the preoptic area (POA). Positive signals for avt and it were highly abundant in PMpc after FW exposure. The data suggest involvement of neurohypophysial hormones in the brain (telencephalon and diencephalon) and pituitary for osmotic stress.

Highlights

IntroductionThe neurohypophysial peptides (nonapeptides) arginine vasotocin (avt) and isotocin (it) are hormones that regulate homeostasis in teleosteans [1]
The neurohypophysial peptides arginine vasotocin and isotocin are hormones that regulate homeostasis in teleosteans [1]
The serum osmolality levels were significantly decreased within the FW black porgy on day 1 and 30

Summary

Introduction

The neurohypophysial peptides (nonapeptides) arginine vasotocin (avt) and isotocin (it) are hormones that regulate homeostasis in teleosteans [1]. Many of the physiological actions of avt and arginine vasopressin (AVP) are common throughout the vertebrate series [11] The avt and it genes are produced in the magnocellular and parvocellular neurons of the preoptic nucleus [10,12,13], and their axons extend to the posterior neurohypophysis of the pituitary gland [6,14,15,16]. The functionality of these extra-hypothalamic projections was confirmed by the presence of avt receptors (avtr: v1a, v1b, v2) and/or it receptors (itr: itr, itr2) in the pituitary of teleosts [6,14,15,17,18]

Methods

Findings

Discussion

Conclusion