The effect of neonatal pinealectomy on the inhibitory actions of food restriction on vaginal opening and collagen aging in the rat.
Long-term food restriction is known to inhibit development and aging in the rat. These actions may be mediated by the pineal hormone, melatonin, whose secretion is increased by food restriction. This mechanism was investigated by studying the effects of pinealectomy in ad libitum fed and food restricted rats of both sexes living under normal conditions of temperature (23 degrees C) and lighting 12 h light:12 h dark cycle) over a period of 400 days. Pinealectomies were performed at the age of 5 days. Pinealectomy did not affect the amount of food eaten per day. Vaginal opening occurred at age 35 days in ad libitum fed female rats and was delayed to 49 days (P < 0.001) in rats whose food intake was restricted by 35%, but only to 41 days (P < 0.001) if food restricted (FR) rats were pinealectomized (Px). The inhibitory effect of food restriction on body growth and tail tendon collagen fibre aging was the same in both intact and pinealectomized rats. At the conclusion of the study in middle age at 400 days, plasma melatonin levels 4 h into the dark cycle were higher in food restricted than in ad libitum fed rats (P = 0.015). This study provides evidence for a role of the pineal in mediating the inhibitory action of food restriction on vaginal opening, but not on body growth or collagen aging in tail tendon up to middle age.
Everitt
A V
AV
School of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
Destefanis
P
P
Parkes
A A
AA
Cairncross
K D
KD
Eyland
A
A
D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D003094:Collagen / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D008550:Melatonin / Q000097:blood; D010870:Pineal Gland / Q000601:surgery*; D051381:Rats; D017208:Rats, Wistar; D013623:Tail / Q000502:physiology; D013710:Tendons / Q000502:physiology; D014621:Vagina / Q000502:physiology*
D003094:Collagen; D008550:Melatonin