Specific inhibition of pituitary prolactin production by energy restriction in C3H/SHN female mice.
Pituitaries were excised from control (C; 95 kcal/week) or energy restricted (ER; 48 kcal/week) female mice of 2, 3, 7, and 18 months of age. The total RNA and relative actin mRNA amounts in the pituitary were significantly greater in C than in ER mice both at 7 and 18 months. Prolactin (PRL) mRNA, standardized with actin mRNA, was significantly less in ER mice of 7 (50%) and 18 (51%) months of age than in age-matched controls, suggestive of specific inhibition of PRL mRNA transcription. Pituitary RNA and actin mRNA increased from 7 to 18 months in C mice but not in ER mice. Similarly, mean pituitary volumes increased between 2 and 18 months in C mice but not in ER mice. PRL mRNA, standardized with actin mRNA, did not change in either C or ER mice 7-18 months of age. All examined C mice of 3, 7, and 18 months of age had estrous cycles but none of the ER mice of the same ages. After 1 month of ER, the pituitary volumes and serum insulin concentrations in 2-month-old female mice were reduced. Thus net reduction of PRL mRNA per pituitary by ER is attributable to decreases in pituitary size and specific inhibition of PRL production, both of which may be due to low estrogen and insulin levels.
Koizumi
A
A
Department of Hygiene, Akita University School of Medicine, Japan.
Tsukada
M
M
Masuda
H
H
Kamiyama
S
S
Walford
R L
RL
D000199:Actins / Q000378:metabolism; D000818:Animals; D001284:Atrophy / Q000209:etiology; D001786:Blood Glucose / Q000378:metabolism; D002149:Energy Intake / Q000502:physiology; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D007328:Insulin / Q000097:blood; D008325:Mammary Neoplasms, Experimental / Q000517:prevention & control; D051379:Mice; D008809:Mice, Inbred C3H; D010902:Pituitary Gland / Q000378:metabolism* / Q000473:pathology; D011388:Prolactin / Q000096:biosynthesis*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
D000199:Actins; D001786:Blood Glucose; D007328:Insulin; D012333:RNA, Messenger; D012313:RNA; D011388:Prolactin