Photoperiod–temperature and neuroblast proliferation–migration in the adult lizard cortex

Ramírez, Carlos; Nácher, Juan; Molowny, A.; Sánchez-Sánchez, Francisco; Irurzun, Alicia; López‐García, Carlos

doi:10.1097/00001756-199707070-00047

Cited by 45 publications

(39 citation statements)

References 8 publications

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“…Confirming this hypothesis, Ramírez et al (1997) and Peñafiel et al (2001) have reported that temperature increases neurogenesis and neuroblast migration in the brain of adult lizards.…”

Section: Environment Temperature Affects Cell Proliferation In the Spmentioning

confidence: 74%

Environment temperature affects cell proliferation in the spinal cord and brain of juvenile turtles

Radmilovich¹,

Fernández

Trujillo‐Cenóz

2003

Journal of Experimental Biology

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SUMMARY The spinal cords and brains - comprising dorsal cortex (DC), medial cortex(MC) and diencephalon (Dien) - of juvenile turtles acclimated to warm temperature [27-30°C; warm-acclimated turtles (WATs)] revealed higher density values of bromodeoxyuridine-labeled cells (BrdU-LCs) than those acclimated to a cooler environment [5-14°C; cold-acclimated turtles(CATs)]. Both populations were under the influence of the seasonal daily light-dark rhythms. Pronounced differences between WATs and CATs (independent t-test; confidence level, P<0.01) were found in the central area of the spinal gray matter and in the ependymal epithelium lining the brain ventricles. Forebrain regions (DC, MC and Dien) also revealed significant differences between WATs and CATs (independent t-test;confidence level, P<0.01-0.05). Unexplored biological clocks that may be affecting cell proliferation were equalized by performing paired experiments involving one WAT and one CAT. Both animals were injected on the same day at the same time and both were sacrificed 24 h later. These experiments confirmed that a warm environment increased cell proliferation in the CNS of turtles. Double- and triple-labeling experiments involving anti-BrdU antibody together with anti-glial protein antibodies revealed that temperature modulates not only cell populations expressing glial markers but also other cells that do not express them. As expected, in the case of short post-injection (BrdU) surviving time points, no cells were found colabeling for BrdU and NeuN (neuronal marker). The probable direct effect of temperature on the cell division rate should be analyzed together with potential indirect effects involving increased motor activity and increased food intake. The fate of the increased BrdU-LCs (death, permanence as progenitor cells or differentiation following neuronal or glial lines) remains a matter for further investigation. Results are discussed in the light of current opinions concerned with post-natal neurogenesis in vertebrates.

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“…Confirming this hypothesis, Ramírez et al (1997) and Peñafiel et al (2001) have reported that temperature increases neurogenesis and neuroblast migration in the brain of adult lizards.…”

Section: Environment Temperature Affects Cell Proliferation In the Spmentioning

confidence: 74%

Environment temperature affects cell proliferation in the spinal cord and brain of juvenile turtles

Radmilovich¹,

Fernández

Trujillo‐Cenóz

2003

Journal of Experimental Biology

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“…In fact, the generation of neurones appears to persist throughout the entire life span of individuals, although aging implies a decrease in the generative potential of the subjacent ependyma (LopezGarcia et al 1988c). Despite the fact that postnatal neurogenetical activity is subject to seasonal varia- tions (Ramirez et al 1997), it results in quadrupling the number of neurones in the medial cortex (LopezGarcia et al 1984) over the normal life span (about five years) (Caetano et al 1986) of the common lizard Podarcis hispanica.…”

Section: Postnatal Neurogenesismentioning

confidence: 99%

“…The explanation is that winter-low temperature prevents migration of newly generated neurones (Ramirez et al 1997). Additionally, winter short daylight periods decreases the proliferating activity of ependymal-stem cells to avoid tumor-like accumulation of cells close to the ependyma.…”

Section: Final Comment On Neuronal Regenerationmentioning

confidence: 99%

The lizard cerebral cortex as a model to study neuronal regeneration

López‐García

Molowny

Nácher

et al. 2002

An. Acad. Bras. Ciênc.

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The medial cerebral cortex of lizards, an area homologous to the hippocampal fascia dentata, shows delayed postnatal neurogenesis, i.e., cells in the medial cortex ependyma proliferate and give rise to immature neurons, which migrate to the cell layer. There, recruited neurons differentiate and give rise to zinc containing axons directed to the rest of cortical areas, thus resulting in a continuous growth of the medial cortex and its zincenriched axonal projection. This happens along the lizard life span, even in adult lizards, thus allowing one of their most important characteristics: neuronal regeneration. Experiments in our laboratory have shown that chemical lesion of the medial cortex (affecting up to 95% of its neurons) results in a cascade of events: first, massive neuronal death and axonal-dendritic retraction and, secondly, triggered ependymal-neuroblast proliferation and subsequent neo-histogenesis and regeneration of an almost new medial cortex, indistinguishable from a normal undamaged one. This is the only case to our knowledge of the regeneration of an amniote central nervous centre by new neuron production and neo-histogenesis. Thus the lizard cerebral cortex is a good model to study neuronal regeneration and the complex factors that regulate its neurogenetic, migratory and neo-synaptogenetic events.

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“…Seasonally variable neurogenesis and recruitment has also been demonstrated in the hippocampus of avian brains Nottebohm, 1994, 1996;Tramontin and Brenowitz, 2000). In reptiles, adult neurogenesis results in new growth of several telencephalic areas and appears to be seasonally regulated (Ramirez et al, 1997). In decapod crustaceans, persistent neurogenesis among olfactory projection neurons is a common principle that shapes the adult brain, indicating a remarkable degree of lifelong structural plasticity (Harzsch et al, 1999).…”

Section: Introductionmentioning

confidence: 99%