Environmental enrichment increases PACAP levels in the CNS of adult rats.

OBJECTIVE: Pituitary adenylate cyclase activating polypeptide (PACAP) is a pleiotropic and multifunctional neuropeptide, widely distributed throughout the body. It is involved in the regulation of various physiological and pathophysiological processes. Numerous studies have shown that PACAP is involved in the development of the central nervous system and has neuroprotective effects. Environmental enrichment is also protective in various injuries, partially through involvement of trophic factors. The interaction between PACAP levels in the brain and environmental effects has not been studied yet. The aim of the present study was to investigate whether environmental enrichment influences PACAP levels of different brain areas in rats.

METHODS: Wistar rats were exposed to enriched environment in adulthood for 3 weeks. PACAP27- and PACAP38-like immunoreactivities were measured with a specific and sensitive radioimmunoassay in homogenates of different brain areas: brainstem, cerebellum, diencephalon and telencephalon.

RESULTS: We found that levels of both PACAP27- and PACAP38-like immunoreactivities showed significant increases in most brain areas after a 3-week-long exposure to enriched conditions. Thus, similarly to several other CNS injuries, enriched environment induced elevation in PACAP levels.

CONCLUSION: As PACAP has strong neuroprotective effects, the elevation observed after exposure to enriched environment is suggested to play a role in the protective effects of such an environment as part of the endogenous neuroprotective machinery in adult rats.