Ventilatory and cardiovascular actions of centrally and peripherally administered trout pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) in the unanaesthetized trout

Abstract

SUMMARY V TOT ). However, the maximum hyperventilatory effect of PACAP was approximately 2.5-fold higher than the effect of VIP at the 100pmol dose (PACAP, V TOT +5407±921arbitrary units, a.u.; VIP, V TOT +2056±874a.u.; means ± s.e.m.). When injected centrally, only PACAP produced a significant increase in mean dorsal aortic blood pressure (P DA ) (100pmol: +21%) but neither peptide affected heart rate (f H ). Intra-arterial injections of either PACAP or VIP were without effect on the ventilatory variables. PACAP was without significant action on P DA and f H while VIP significantly elevated P DA (100pmol: +36%) without changing f H . In conclusion, the selective central hyperventilatory actions of exogenously administered trout PACAP, and to a lesser extent VIP, suggest that the endogenous peptides may be implicated in important neuroregulatory functions related to the central control of ventilation in trout.

Activation of PAC1 and VPAC receptor subtypes elicits differential physiological responses from sympathetic preganglionic neurons in the anaesthetized rat

“…Previous studies found that intrathecal VIP, administered at the spinal level of T2, did not affect MAP in the rat (Lai et al ., 1997), and that intracerebroventricular VIP did not affect MAP or HR in the trout (Le Mevel et al ., 2009). Apart from the differences in sites of VIP administration and species, the much lower doses used in these earlier studies may account for the lack of observed MAP and HR responses.…”

Brain neuropeptides in central ventilatory and cardiovascular regulation in trout

“…In the goldfish, peripheral PACAP reduces food intake (Matsuda et al, 2006). We also demonstrated that trout PACAP-27 and trout VIP act on the CNS to increase ventilation (Le Mével et al, 2009b) and to reduce the cardiac BRS (Lancien et al, 2011). …”

“…The most pronounced action of PACAP is evoking hyperventilation through an increase in VA rather than VF. For instance, after 50 and 100 pmol PACAP this maximal change in VA, expressed as a percentage of the pre-injection value, reaches about 100 and 200%, respectively, while the elevation of VF is only about 10 and 35% (Le Mével et al, 2009b). …”