Mice with a condition that serves as a laboratory model for Down syndrome perform better on memory and learning tasks as adults if they get prenatal treatment with neuroprotective peptides, according to researchers at the National Institutes of Health.
These mice had an extra copy of mouse chromosome 16, which has mouse counterparts to 55% of the genes on human chromosome 21.
In an online paper published November 29 in PLOS One, researchers led by Catherine Spong, MD, reported that prenatal treatment with peptides NAP and SAL, which are subunits of the proteins NAPVSIPQ and SALLRSIPA and important at certain key stages of prenatal brain development, prevented learning deficits in these mice.
Pregnant female and control pregnant females were randomly treated during days 8 through 12 of pregnancy with either a saline placebo or 20 µg of NAP plus 20 µg of SAL. The researchers assessed learning capability of offspring at 8 to 10 months by measuring how much time the mice took to complete water maze experiments that evaluated spatial learning, a measure of cognitive function.
Pups were genotyped as trisomic (Down syndrome) or euploid (control) after completion of all tests. In all, 33 control and 11 DS mice received placebos, while 30 control and 10 DS mice from litters received peptides.
Trisomic mice that were given prenatal placebos did not demonstrate learning over the five-day period, while those that were prenatally exposed to peptides learned significantly better, similar to control mice that received placebos. The trisomic mice that received peptides completed mazes in an average of about 62 seconds on day one, and approximately 35 seconds on day two, while control mice completed day one tests in about 63 seconds, and day five tests in about 27 seconds, on average.