A comparative study of the effects of neonatal androgenization and estrogenization on prolactin secretion in adult female rats.
Effects of neonatal androgenization (NA) and estrogenization (NE) were compared especially in terms of the prolactin (PRL) secretion in female rats. Twenty-four h after birth, a total of seven groups of newborn female rats were treated as follows. Three NA groups received a single s.c. injection of 10, 100 or 1000 micrograms of testosterone, respectively. Similarly, three NE groups received 1, 10 or 100 micrograms of estradiol-17 beta, respectively. The remaining one group was injected with oil vehicle only, and served as controls. At 8 weeks of age, animals were killed by rapid decapitation. PRL, estradiol and progesterone were measured in the plasma. Anterior pituitary (AP) was weighed, and AP PRL content was measured. NA and NE, at the highest doses, resulted in a similar degree of hyperprolactinemia and hyperestrogenemia showing an effect ratio of about 1:10. This ratio was, however, not true with the lower doses. Furthermore, there was no dose-dependency in the effect of NE on the plasma PRL and estradiol levels. In turn, plasma progesterone levels were dose-dependently decreased by both NA and NE. AP PRL content, expressed per AP, was significantly higher than control values in only NA (1000 micrograms) and NE (100 micrograms) groups. AP weight was increased by NA (1000 micrograms) but not by any NE treatment. These results indicate that NA and NE do not always exert similar effects on the PRL secretion or on several other related parameters. Therefore, aromatization of testosterone to estradiol does not appear to be the sole mechanism mediating the neuroendocrine consequences of NA.
Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan.
H
H
Watanobe
S
S
Sasaki
K
K
Takebe
D000818:Animals; D000831:Animals, Newborn; D004958:Estradiol / Q000097:blood / Q000502:physiology*; D005260:Female; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000097:blood*; D051381:Rats; D013739:Testosterone / Q000502:physiology*
D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin