Table 1.

Neotenic traits of adult naked mole rats

NumberTrait
1Much lower body weight than for 20 related species–members of the Bathyergidae family (99).
2Absence of hair (unique among adult rodents) (138).
3Much longer gestation than is expected based on body weight (45, 67, 82).
4Much longer time to maturity than for other rodents (67).
5An increase of reproductive success with age (rather than the decline observed in other mammals) (21).
6Absence of auricles, as in newborns and in contrast to other adult mammals (138).
7Absence of scrotum, as in newborns (67, 76).
8Very small vomeronasal organ, as in newborns (43, 160).
9Limited ability to maintain a constant body temperature, as in newborns (20, 23, 115).
10Age-linked diseases such as cancer, diabetes, and cardiovascular, brain, liver, and some kidney pathologies, as well as many infections are very rare or absent as causes of death of naked mole rats (as is the case in mammalian juveniles) (37, 43).
11Absence of age-linked declines in cognitive functions (43).
12No perception of pain caused by capsaicin and acid due to the lack of substance P (115).
13Very high resistance of brain neurons to anoxia and subsequent oxidative stress during reoxygenation (as in newborns) (84, 85).
14Continual presence of the GluN2D subunit of the NMDA (glutamate) receptor in adulthood, which is inherent in other mammals in newborns only (123).
15No Ca2+ overload under long-term excitation of neurons (85, 124).
16Neonatal-type distribution of calbindin in the CA3 region of the hippocampus (4).
17Lack of synaptic paired-pulse facilitation and low sensitivity to exogenous adenosine in the hippocampus, in contrast to the effects in other adult mammals (4, 85).
18Very long time-frame for brain development compared with that of other rodents (118).
19Maintenance of the capacity for the regeneration and elongation of neurons during adulthood (4, 43, 44, 170).
20Inactivation of the gene encoding FAS-activated serine/threonine kinase (FASTK), an antiapoptotic and proinflammatory enzyme (44).
21Underdevelopment of numerous morphological aspects of the lungs (93, 94).
22Pulmonary neuroepithelial bodies, which normally decrease in number during the first postnatal week, are present in high numbers in naked mole rats at ages greater than 2 wk (113).
23No decrease in the elasticity of blood vessels with age (21, 109).
24No decline of bone cortical area with age (21).
25Delayed maturation of the skeleton system (59).
26No age-related decline in bone mineral density (21, 109).
27Absence of any decline in the state of articular cartilage with age (21).
28Sensitivity of naked mole rat smooth muscle to NO does not decrease with age, in contrast to changes observed in other rodents (31, 33).
29Strong delay of the development of a united mitochondrial system (Reticulum mitochondriale) during the postnatal period in skeletal muscles (62).
30An increase, rather than decrease, in the number and activity of mitochondria with age (32, 43, 62).
31No age-linked decrease in metabolic rate (21, 109).
32Absence of any increase in the peroxidation index of lipids and their oxidative damage, which are observed with age in other mammals (5, 43, 120).
33No increase in ROS production with age (31, 32, 43).
34No decrease in the levels of superoxide dismutases 1 and 2 and catalase with age (6, 43, 63).
35Reduced levels of adenine nucleotides in the adult naked mole rat mitochondria and higher respiration rates after the exhaustion of ADP (as in the rat and mouse embryos and neonates) (62).
36Unusually high proteasome activity in adulthood (43, 133, 134, 171).
37Changes in the insulin b-chain sequence, resulting in a reduction of hormonal activity to embryonic levels (44, 120).
38No reduction in IGF2 levels in adult naked mole rats (44).
39Decreased expression of IGF1 and insulin-induced gene 2 (INSIG2) and increased expression of IGF1R and resistin (RETN) genes in adult naked mole rats (44).
40No decline in glucose tolerance in old animals (21, 22).
41No effect of aging on the level of glycated hemoglobin (21, 181).
42Permanent presence of high-molecular-weight hyaluronan in the intercellular spaces (168).
43Very long maximal lifespan; compared with other rodents, a very low mortality rate that increases only slightly at least during the first 24 yr (20, 43).