[Sequential and ultrastructural study of lactotroph response to stress in rats as a function of age].
In adult rats, ether inhalation stress stimulated basal serum prolactin (PRL) significantly, within a maximum delay of one minute. The same pattern was seen with immature animals of 15-20 and 30 days of age. In contrast, in 2 or 6 days old neonates, serum PRL concentrations remained unaffected by stress. This lack of responsiveness suggests the existence of a transient impairment of lactotroph hormones to stressful stimuli during postnatal life. This hypothesis has been controlled by ultrastructural exploration of lactotrophs. The distribution of organites and secretion grains in lactotrophs was similar in unstressed neonates and adult rats, but after ether stress, the distribution of secretion grains became different with age. Adult lactotrophs showed a peripheral secretion grains aspects indicating cells discharge. In the very young rats, the grains were distributed in the totality of the cytoplasm. These results confirm the existence, in the lactotrophs, of a refractory period to stress in the neonate rats.
el Feki
A
A
Laboratoire de Physiologie Animale, Faculté des Sciences de Sfax, Tunisie.
Hjaiej
L
L
Zekri
S
S
Jaafoura
H
H
Kamoun
A
A
D000375:Aging / Q000378:metabolism*; D000818:Animals; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D010903:Pituitary Gland, Anterior / Q000378:metabolism / Q000648:ultrastructure; D011388:Prolactin / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000097:blood*
D011388:Prolactin