Pituitary adenylate cyclase activating polypeptide (PACAP) is a multifunctional neuropeptide.
In addition to its diverse physiological roles, PACAP has important functions in the
embryonic development of various tissues, and it is also considered as a trophic factor
during development and in the case of neuronal injuries. Data suggest that the development
of the nervous system is severely affected by the lack of endogenous PACAP. Short-term
neurofunctional outcome correlates with long-term functional deficits; however, the
early neurobehavioral development of PACAP-deficient mice has not yet been evaluated.
Therefore, the aim of the present study was to describe the postnatal development
of physical signs and neurological reflexes in mice partially or completely lacking
PACAP. We examined developmental hallmarks during the first 3 weeks of the postnatal
period, during which period most neurological reflexes and motor coordination show
most intensive development, and we describe the neurobehavioral development using
a complex battery of tests. In the present study, we found that PACAP-deficient mice
had slower weight gain throughout the observation period. Interestingly, mice partially
lacking PACAP weighed significantly less than homozygous mice. There was no difference
between male and female mice during the first 3 weeks. Some other signs were also
more severely affected in the heterozygous mice than in the homozygous mice, such
as air righting, grasp, and gait initiation reflexes. Interestingly, incisor teeth
erupted earlier in mice lacking PACAP. Motor coordination, shown by the number of
foot-faults on an elevated grid, was also less developed in PACAP-deficient mice.
In summary, our results show that mice lacking endogenous PACAP have slower weight
gain during the first weeks of development and slower neurobehavioral development
regarding a few developmental hallmarks.