Effects of arginine vasotocin, isotocin and melatonin on blood pressure in the conscious atlantic cod (Gadus morhua): hormonal interactions?

Abstract

SUMMARYThe effects of exogenous arginine vasotocin (AVT), isotocin (IT) and melatonin on the blood pressure of conscious Atlantic cod (Gadus morhua) were examined. Ventral aortic blood pressure (PVA) was recorded from a cannula inserted into the afferent branchial artery of the third gill arch.Dorsal aortic blood pressure (PDA) was recorded via a cannula implanted into the efferent branchial artery in the same gill arch. Each fish received two doses (10 and 50 ng kg-') of AVT, IT and melatonin. AVT was also administered in combination with melatonin. Injection of 10 ng kg-1 AVT produced significant hypertension, especially in animals injected during the daytime. In contrast, the same dose of IT induced no significant change in either PVA or PDA.Administration of 10 ng kg-' melatonin at night caused a long-lasting decrease in both parameters.Melatonin also inhibited the increase in blood pressure elicited by AVT. These results indicate that AVT, but not IT, is vasopressor in the cod. The effects of combined administration of melatonin and AVT show the antihypertensive action of melatonin in AVT-induced hypertension.

Unraveling the Tissue-Specific Gene Signatures of Gilthead Sea Bream (Sparus aurata L.) after Hyper- and Hypo-Osmotic Challenges

“…Functional analysis of differentially expressed genes also highlighted that xenobiotic metabolism was co-regulated with melatonin-related genes. Melatonin hormone is secreted by the pineal gland and it is an important player in several functions related to osmoregulation [ 58 – 60 ], but also to interact with other well-known osmoregulatory fish hormones produced in the hypothalamus, like arginine vasotocin or isotocin [ 61 , 62 ]. In addition, salinity transfer promoted thyroid hormone metabolism in peripheral tissues (e.g.…”

The Hypothalamic Neuropeptide Oxytocin Is Required for Formation of the Neurovascular Interface of the Pituitary

“…isotocin) regulates contraction of smooth muscles in the ovary and oviduct during parturition or oviposition of live bearing and egg laying fish (La Pointe, 1977; Peter and Fryer, 1983). Avpl and Oxtl also regulate blood pressure in the ventral aorta (Chan, 1977; Kulczykowska, 1998; Le Mevel et al, 1993; Peter and Fryer, 1983). The HNS is therefore a central point of interface between the hormonal, neuronal, and vascular systems common to all vertebrate species.…”

Hormonal Modulation of Aggression: With a Focus on Teleost Studies

“…However, the peripheral functions of isotocin are not as clear as that of AVT. Isotocin administration causes blood pressure reduction in the dorsal aorta in the fl ounder (Warne and Balment 1997b ) , but not in certain other species (Bennett and Rankin 1986 ;Kulczykowska 1998 ;Le Mevel et al 1993 ) . It is unclear whether such differences in the action of isotocin are due to species differences, and this requires further investigation.…”