Effects of central and peripheral administration of arginine vasotocin and related neuropeptides on blood pressure and heart rate in the conscious trout

Neurophysiological Effects of Vasotocin and Corticosterone on Medullary Neurons: Implications for Hormonal Control of Amphibian Courtship Behavior

“…AVT application to the medulla may have elicited a pressor effect [11]. But a number of observations indicate that the neurophysiological effects of this peptide were not secondary to changes in central vascular tone or blood pressure.…”

“…In the roughskin newt (Taricha granulosa) for example, arginine vasotocin (AVT), the presumed evolutionary precursor of vasopres sin [7], acts centrally to facilitate courtship clasping of females by males [8], but this effect depends on a priming action of testicular steroid hormones [6], Of interest to the present study is the evidence for interactions between glucocorticoids and neurohypophy seal peptides. In contrast to the evidence that glucocorti coids such as corticosterone (CORT) suppress reproduc tive behaviors [9] and peptides such as vasopressin [ 1,10] and AVT [8] facilitate these behaviors is the fact that these hormones are also mediators of neuroendocrine stress responses [3][4][5]7,[9][10][11], The relationships between stress stimuli and the actions of these steroids and neuro peptides are quite complex, however, and the exact pat tern of release and neuroendocrine consequences of these hormones is very context-specific [10]. It is clear, though, that the interactions between vasopressin and corticoste rone vary in direction of effect, sometimes being posi tively correlated, sometimes negatively [3,5,10], Given the evidence for opposite effects of CORT and AVT on reproductive behavior in roughskin newts, as well as the interactive nature of similar classes of hor mones in mammals, it would appear that these hormones might exert opposing effects on neurons or neuronal sys tems that subserve reproductive behavior.…”

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

“…However, this is the first attempt to compare the effects of melatonin, isotocin and a combination of melatonin and AVT in a single study performed in conscious teleost fish. Arginine vasotocin has been found to increase the systemic blood pressure in conscious rainbow trout, flounder and eel (Le Mevel et al 1993;Oudit & Butler, 1995;Warne & Balment, 1997). The mean plasma AVT levels reported in fish show great variation, probably due to differences in assay technique, species and physiological state (Perrott, Carrick & Balment, 1991;Balment et al 1993;Warne, Hazon, Rankin & Balment, 1994;Kulczykowska & Stolarski, 1996;Kulczykowska, 1997).…”

“…Although the physiological role of AVT is poorly understood the literature strongly suggests the contribution of the hormone to the maintenance of salt and fluid balance and to regulation of some cardiovascular parameters and endocrine secretion in teleosts (Babiker & Rankin, 1979;Groves & Batten, 1986;Balment, Warne, Tierney & Hazon, 1993;Uchiyama & Murakami, 1994;Amer & Brown, 1995; & Balment, 1995;Pierson, Guibbolini & Lahlou, 1996). Systemic administration of AVT induces elevation of blood pressure in various non-mammalian vertebrates (Babiker & Rankin, 1979;Le Mevel, Mabin & Vaudry, 1991;Chiu, Lee & Pang, 1993;Le Mevel, Pomantung, Mabin & Vaudry, 1993;Robinzon, Koike & Marks, 1993;Oudit & Butler, 1995) and the hormone may play a role in regional blood flow distribution in fish (Warne & Balment, 1997). It has been demonstrated that the neurohypophysial peptides constrict the branchial vessels in fish (Chan & Chester-Jones, 1969;Rankin & Maetz, 1971; Bennett & Rankin, 1986).…”

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.…”