Phospholipids modulate the biophysical properties and vasoactivity of PACAP-(1—38)

Abstract

The purpose of this study was to elucidate the interactions between pituitary adenylate cyclase-activating peptide (PACAP)-(1--38) and phospholipids in vitro and to determine whether these phenomena modulate, in part, the vasorelaxant effects of the peptide in the intact peripheral microcirculation. We found that the critical micellar concentration of PACAP-(1--38) was 0.4-0.9 microM. PACAP-(1--38) significantly increased the surface tension of a dipalmitoylphosphatidylcholine monolayer and underwent conformational transition from predominantly random coil in saline to alpha-helix in the presence of distearoyl-phosphatidylethanolamine-polyethylene glycol (molecular mass of 2,000 Da) sterically stabilized phospholipid micelles (SSM) (P < 0.05). Using intravital microscopy, we found that aqueous PACAP-(1--38) evoked significant concentration-dependent vasodilation in the intact hamster cheek pouch that was significantly potentiated when PACAP-(1--38) was associated with SSM (P < 0.05). The vasorelaxant effects of aqueous PACAP-(1--38) were mediated predominantly by PACAP type 1 (PAC(1)) receptors, whereas those of PACAP-(1--38) in SSM predominantly by PACAP/vasoactive intestinal peptide type 1 and 2 (VPAC(1)/VPAC(2)) receptors. Collectively, these data indicate that PACAP-(1--38) self-associates and interacts avidly with phospholipids in vitro and that these phenomena amplify peptide vasoactivity in the intact peripheral microcirculation.

Freeze drying of peptide drugs self-associated with long-circulating, biocompatible and biodegradable sterically stabilized phospholipid nanomicelles

“…To this end, we showed that self-association of amphipathic peptide drug candidates, such as vasoactive intestinal peptide (VIP), with long-circulating, biocompatible and biodegradable sterically stabilized phospholipid nanomicelles (SSM) increases peptide stability in vitro and prolongs and amplifies its bioactivity in vivo (Önyüksel et al, 1999;Tseushita et al, 2002;Krishnadas et al, 2003). Importantly, given their distinct physico-chemical characteristics, these nanosized constructs are preferentially targeted to inflamed and injured tissues through local 'leaky' microcirculation (Sethi et al, 2003a).…”

Pulmonary and systemic effects of inhaled PACAP38 in healthy male subjects

“…Neuropeptide receptor up‐regulation in the lung is described in idiopathic pulmonary arterial hypertension (IPAH) [11] and pulmonary inflammation [26] which may contribute to sustained peptide stability by immediate receptor binding of VIP or PACAP. Tsueshita and Krishnadas have shown that phospholipids stabilize and modulate the biophysical properties of PACAP [48,52], which may play an important role in the interaction of PACAP with surfactant which is a mixture of several phospholipids. Furthermore, it has been suggested that inhalative application of VIP (200 µg divided into 4–6 doses) could serve as an effective drug for treatment of IPAH [11].…”

Investigation of the receptorial and molecular mediators of systemic inflammation in different animal models

“…PACAP38 in conscious rats. It indicates that the thermoregulatory (constrictor) effect of PACAP38 on the cutaneous vascular tone is different from its direct (dilator) effect on skin vessels, which was shown earlier in small rodents (Absood et al 1992; Tsueshita et al 2002). The initial drop of HLI lasted for 40 min, and then, it was followed by a pronounced elevation of HLI due to tail skin vasodilation, which remained significantly (p<0.05) higher than the HLI of saline-treated rats until the end of the experiment in accordance with the vasodilatory effect of PACAP38 reported earlier (Absood et al 1992; T sueshitaetal.2002).…”