The pituitary adenylate cyclase-activating polypeptide (PACAP) protects adrenal function in septic rats administered etomidate

The Potential of the Nose-to-Brain Delivery of PACAP for the Treatment of Neuronal Disease

Research on the neuroprotective effect of pituitary adenylate cyclase-activating polypeptide (PACAP) and its use as a therapeutic agent has grown over the past 30 years. Both in vitro and in vivo experiments have shown that PACAP exerts a strong neuroprotective effect in many central and peripheral neuronal diseases. Various delivery routes have been employed from intravenous (IV) injections to intracerebroventricular (ICV) administration, leading either to systemic or topical delivery of the peptide. Over the last decade, a growing interest in the use of intranasal (IN) administration of PACAP and other therapeutic agents has emerged as an alternative delivery route to target the brain. The aim of this review is to summarize the findings on the neuroprotective effect of PACAP and to discuss how the IN administration of PACAP could contribute to target the effects of this pleiotropic peptide.

Effects of pituitary adenylate cyclase activating polypeptide on small intestinal INT 407 cells

Pituitary adenylate cyclase activating polypeptide (PACAP) is an endogenous neuropeptide having a widespread distribution both in the nervous system and peripheral organs including the gastrointestinal tract. It has been shown to exert actions on intestinal functions, mainly affecting glandular secretion and motility. PACAP has several different effects on cell survival depending on the cell type and the applied stimulus. Its influences on small intestinal epithelial cells are not yet elucidated, therefore the aim of the present study was to investigate the effects of PACAP on intestinal epithelial cells having high turnover (INT 407) against different harmful stimuli, such as oxidative stress, in vitro hypoxia and gamma radiation. We tested the effect of PACAP on proliferation and cell survival using MTT assay. Moreover, various cancer-related factors were evaluated by oncology array. PACAP did not influence the proliferation rate of INT 407 cells. Its cell survival-enhancing effect could be detected against oxidative stress, but not against in vitro hypoxia or gamma irradiation. Clonogenic survival assay was performed to analyze the effect of PACAP on clonogenic potential of cells exposed to gamma radiation. Surprisingly, PACAP enhanced the clone-forming ability decrease induced by irradiation. Western blot analysis of ERK1/2 phosphorylation was performed in order to obtain further information on the molecular background. Our data showed phospho-ERK1/2 suppression of PACAP in irradiated cells. Furthermore, the role of endogenous PACAP against oxidative stress was also investigated performing ADCYAP1 small interfering RNA transfection. We found significant difference in the cell vulnerability between cells undergoing silencing and cells without transfection suggesting the protective role of the endogenously present PACAP against oxidative stress in INT 407 cells. In summary, PACAP seems to be able to exert contradictory effects in INT 407 cells depending on the applied stressor, suggesting its regulatory role in the cellular household.