Reproductive aging in the Djungarian hamster, Phodopus campbelli

• Published in: Biology of reproduction Vol. 58; no. 3; pp. 842 - 848
• Main Authors: Edwards, H E, Tweedie, C J, Terranova, P F, Lisk, R D, Wynne-Edwards, K E
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-03-1998
• Subjects: Aging - physiology; Animals; Biological and medical sciences; Chorionic Gonadotropin - pharmacology; Cricetinae; Estradiol - metabolism; Female; Fertility - physiology; Fundamental and applied biological sciences. Psychology; Hypothalamo-Hypophyseal System - physiology; Litter Size; Male; Mice; Models, Biological; Ovarian Follicle - physiology; Ovary - drug effects; Ovary - physiology; Phodopus - physiology; Pregnancy; Reproduction - physiology; Sexual differentiation and maturation. Puberty. Climacterium; Species Specificity; Vertebrates: reproduction; Hypothalamohypophysoovarian axis; Estrogen; Rodentia; 17β-Estradiol; Ovarian hormone; Pregnancy; Vertebrata; Mammalia; Fertility; Hormonal investigation; Progesterone; Sex steroid hormone; Fecundity; Age; Hamster
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod58.3.842

Changes in fertility (delivery success), fecundity (litter size and weaning success), sensitivity to pregnancy-blocking stimuli
(mate removal after 24 h), and hypothalamic-pituitary-ovarian function were assessed during reproductive aging in the Djungarian
hamster, Phodopus campbelli. All indices of aging occurred earlier in the Djungarian hamster than they do in other laboratory
models, including the mouse. Fertility and fecundity were halved by 8 mo of age, and the response to pregnancy-blocking stimuli
disappeared by 4-6 mo. Pup birth weight increased with maternal age and decreasing litter size. Older females also tended
to lose entire litters rather than to reduce litter size and successfully wean remaining pups. Impaired ovarian function was
a major contributor to reproductive aging. Numbers of large antral follicles developing in aged females and in aged females
receiving eCG treatment were similar to those in young females. However, a few preovulatory follicles routinely failed to
ovulate from each ovary. Healthy preovulatory follicles in old females secreted the large quantities of estradiol-17 beta
typical of estrous cycles, but eCG-induced preovulatory follicles did not. As young females of this species have smaller folicular
reserves than other rodent species, and follicle numbers in older females are further reduced (with a high incidence of completely
degenerate ovaries), follicular exhaustion was coincident with reproductive failure. Neuroendocrine aging of the hypothalamus
was also implicated in the loss of a pregnancy-blocking response and the failure of maternal care with increasing maternal
age. Similarities to reproductive aging in long-cycle species (including primates) suggest that the Djungarian hamster is
a useful laboratory model that deserves further investigation.