Effects of Brain Size on Adult Neurogenesis in Shrews

Abstract

Shrews are small animals found in many different habitats. Like other mammals, adult neurogenesis occurs in the subventricular zone of the lateral ventricle (SVZ) and the dentate gyrus (DG) of the hippocampal formation. We asked whether the number of new generated cells in shrews depends on their brain size. We examined Crocidura russula and Neomys fodiens, weighing 10–22 g, and Crocidura olivieri and Suncus murinus that weigh three times more. We found that the density of proliferated cells in the SVZ was approximately at the same level in all species. These cells migrated from the SVZ through the rostral migratory stream to the olfactory bulb (OB). In this pathway, a low level of neurogenesis occurred in C. olivieri compared to three other species of shrews. In the DG, the rate of adult neurogenesis was regulated differently. Specifically, the lowest density of newly generated neurons was observed in C. russula, which had a substantial number of new neurons in the OB compared with C. olivieri. We suggest that the number of newly generated neurons in an adult shrew’s brain is independent of the brain size, and molecular mechanisms of neurogenesis appeared to be different in two neurogenic structures.

MDPV (3,4-methylenedioxypyrovalerone) administered to mice during development of the central nervous system produces persistent learning and memory impairments

“…Detection of BrdU was performed according to Bartkowska et al [ 37 ] and Tepper et al [ 38 ] with modifications.…”

“…Immunolabeling of neuronal nuclear protein (NeuN) or glial fibrillary acidic protein (GFAP) colocalizing with BrdU was performed according to Bartkowska et al [ 37 ] and Tepper et al [ 38 ] with modifications. Some free-floating brain sections were double-immunostained for BrdU and NeuN or BrdU and GFAP to detect the fate of BrdU-labeled cells.…”

Postnatal and Adult Neurogenesis in Mammals, Including Marsupials

“…Two areas, the SVZ and the dentate gyrus, are well-known neurogenic zones where the proliferation of cells occurs throughout life. According to available data on adult neurogenesis in mammals, new neurons are generated in the adult brain of opossums [ 65 ] and the fat-tailed dunnarts [ 66 ], rodents, including laboratory mice and rats [ 6 , 67 , 68 , 69 ], carnivores [ 70 , 71 ], sheep [ 72 , 73 ], shrews [ 74 , 75 ], giant otter shrews [ 76 ], tree shrews [ 77 , 78 ], the rock hyrax and sengi [ 79 ], hedgehogs and European moles [ 80 ], bats [ 81 , 82 ], and primates, including humans [ 83 , 84 , 85 ]. More and more evidence is currently accumulating about adult brain structures, such as the piriform cortex, cerebral cortex, corpus callosum, striatum, amygdala, and hypothalamus, where cells express different markers for cell proliferation (for review, see [ 16 , 86 ]).…”