S. Jurado et al., SEXUALLY DIMORPHIC EFFECTS OF AGING ON RAT SOMATOTROPH CELLS - AN IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL-STUDY, Journal of veterinary medical science, 60(6), 1998, pp. 705-711
Aging produces alterations in certain functions of the hypothalamo-pit
uitary axis that result in sexually dimorphic changes in the somatotro
phs. Since quantitative morphological data on these age-associated alt
erations are scarce, we prompted to make a morphometric immunohistoche
mical assessment as well as undertake an ultrastructural study of the
somatotrophic (GH) cell population in male and female rats of differen
t ages. Young (3-month-old), old (20-month-old), and senescent (29-mon
th-old) Sprague-Dawley rats of both sexes were sacrificed by rapid dec
apitation, their pituitaries immediately dissected out, and processed
for both immunohistochemistry and electron microscopy. Analysis of dif
ferent morphometric parameters revealed that surface density, volume d
ensity, and cell density significantly decreased in old and senescent
rats as compared to young animals, with this reduction being clearly m
ore marked in females. Both the GH-cell area and perimeter decreased i
n senescent male rats, while these parameters increased in senescent f
emales. The ultrastructure of the GH cells from old and senescent anim
als of both sexes evinced changes suggestive of an immature state, wit
h some somatotrophs having the appearance of cells undergoing an invol
utive process. We conclude that aging has a differential impact on the
GH cells of male and female rats with respect to the immunohistochemi
cal and ultrastructural features of that cell population.