Limits to sustained energy intake. XXXIV. Can the heat dissipation limit (HDL) theory explain reproductive aging?
J Exp Biol
; 227(4)2024 02 15.
Article
em En
| MEDLINE
| ID: mdl-38264846
ABSTRACT
According to the heat dissipation limit (HDL) theory, reproductive performance is limited by the capacity to dissipate excess heat. We tested the novel hypotheses that (1) the age-related decline in reproductive performance is due to an age-related decrease of heat dissipation capacity and (2) the limiting mechanism is more severe in animals with high metabolic rates. We used bank voles (Myodes glareolus) from lines selected for high swim-induced aerobic metabolic rate, which have also increased basal metabolic rate, and unselected control lines. Adult females from three age classes - young (4â
months), middle-aged (9â
months) and old (16â
months) - were maintained at room temperature (20°C), and half of the lactating females were shaved to increase heat dissipation capacity. Old females from both selection lines had a decreased litter size, mass and growth rate. The peak-lactation average daily metabolic rate was higher in shaved than in unshaved mothers, and this difference was more profound among old than young and middle-aged voles (P=0.02). In females with large litters, milk production tended to be higher in shaved (least squares mean, LSM±s.e. 73.0±4.74â
kJâ
day-1) than in unshaved voles (61.8±4.78â
kJâ
day-1; P=0.05), but there was no significan"t effect of fur removal on the growth rate [4.47±2.29â
gâ
(4â
days-1); P=0.45]. The results provide mixed support of the HDL theory and no support for the hypotheses linking the differences in reproductive aging with either a deterioration in thermoregulatory capability or genetically based differences in metabolic rate.
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Base de dados:
MEDLINE
Assunto principal:
Lactação
/
Temperatura Alta
Limite:
Animals
Idioma:
En
Revista:
J Exp Biol
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Polônia