Sexual dimorphism in the granule cell stratum and the mossy fi bers system of the hippocampus in young control and prenatally malnourished rats

Abstract

PRENATAL PROTEIN MALNUTRITION LEADS TO MORE ANATOMICAL ALTERATIONS IN THE HIPPOCAMPUS IN OLDER RATHER THAN IN YOUNGER RATS. HOWEVER, SEX DIFFERENCES ARE UNKNOWN. IN THE PRESENT STUDY WE ESTIMATED THE VOLUME IN THE GRANULE CELL STRATUM (GCS) AND MOSSY FIBER SYSTEM (MFS) IN MALE AND FEMALE 30-DAY-OLD SPRAGUE-DAWLEY RATS, BORN FROM DAMS FED A NORMAL 25% OR 6% CASEIN DIET DURING GESTATION. AT BIRTH, ALL RATS WERE RANDOMLY MIXED AND FED THE 25% CASEIN DIET UNTIL EUTHANIZED. THERE WERE FOUR EXPERIMENTAL GROUPS: 1) MALE CONTROLS, 2) MALE PRENATALLY MALNOURISHED, 3) FEMALE CONTROLS, AND 4) FEMALES PRENATALLY MALNOURISHED. FIVE BRAINS FROM EACH GROUP WERE PERFUSED AND PROCESSED USING THE TIMM´S METHOD. FOR EACH, VOLUME WAS ESTIMATED USING THE CAVALIERI´S PRINCIPLE, AND THE DENTATE GYRUS WAS ANALYZED AS FOLLOWS: A) GCS VOLUME; B) SUPRA AND C) INFRAPYRAMIDAL BUNDLE PLUS THE HILAR REGION, AND D) MFS TOTAL VOLUME. NO SIGNIFICANT SEX-RELATED EFFECTS WERE FOUND ON GCS MEASUREMENTS IN CONTROL ANIMALS. HOWEVER, TOTAL MFS AND SUPRAPYRAMIDAL BUNDLE VOLUMES WERE SIGNIFICANTLY REDUCED IN FEMALE RATS COMPARED TO MALE CONTROLS. ALSO, 30-DAY-OLD FEMALE RATS HAD SIGNIFICANTLY SMALLER GCS AND MFS REGIONS THAN MALNOURISHED MALES. THUS, THIS STUDY SUPPORTS THE HYPOTHESIS THAT THE VOLUME OF THE HIPPOCAMPUS UNDERGOES SEXDEPENDENT CHANGES ESPECIALLY IN RATS THAT WERE PRENATALLY MALNOURISHED.