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Interactions with the young down-regulate adult olfactory neurogenesis and enhance the maturation of olfactory neuroblasts in sheep mothers.

Brus M, Meurisse M, Keller M, Lévy F - Front Behav Neurosci (2014)

Bottom Line: In addition, a morphological analysis was performed by measuring the dendritic arbor of neuroblasts in both structures.We showed that the postpartum period was associated with a decrease in olfactory and hippocampal adult neurogenesis.Our assumption is that fewer new neurons decrease cell competition in the olfactory bulb and enhance maturation of those new neurons selected to participate in the learning of the young odor.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 85, Physiologie de la Reproduction et des Comportements Nouzilly, France ; CNRS, UMR 7247 Nouzilly, France ; Université François Rabelais Tours, France ; IFCE Nouzilly, France.

ABSTRACT
New neurons are continuously added in the dentate gyrus (DG) and the olfactory bulb of mammalian brain. While numerous environmental factors controlling survival of newborn neurons have been extensively studied, regulation by social interactions is less documented. We addressed this question by investigating the influence of parturition and interactions with the young on neurogenesis in sheep mothers. Using Bromodeoxyuridine, a marker of cell division, in combination with markers of neuronal maturation, the percentage of neuroblasts and new mature neurons in the olfactory bulb and the DG was compared between groups of parturient ewes which could interact or not with their lamb, and virgins. In addition, a morphological analysis was performed by measuring the dendritic arbor of neuroblasts in both structures. We showed that the postpartum period was associated with a decrease in olfactory and hippocampal adult neurogenesis. In the olfactory bulb, the suppressive effect on neuroblasts was dependent on interactions with the young whereas in the DG the decrease in new mature neurons was associated with parturition. In addition, dendritic length and number of nodes of neuroblasts were significantly enhanced by interactions with the lamb in the olfactory bulb but not in the DG. Because interactions with the young involved learning of the olfactory signature of the lamb, we hypothesize that this learning is associated with a down-regulation in olfactory neurogenesis and an enhancement of olfactory neuroblast maturation. Our assumption is that fewer new neurons decrease cell competition in the olfactory bulb and enhance maturation of those new neurons selected to participate in the learning of the young odor.

No MeSH data available.


Related in: MedlinePlus

Effects of parturition and/or interactions with the young on the dendritic tree of neuroblasts. (A, D) Length of dendritic processes of BrdU+/DCX+ cells (16–18 cells/animal) in the granular layer of the MOB (A) and in the granular cell layer of the DG (D) in the “Virgin” (n = 6), the “No Lamb” (n = 6) and the “With Lamb” (n = 5) groups. (B, E) Percentage of BrdU+/DCX+ cells which displayed one or more nodes in each group in the granular layer of the MOB (B) and in the granular cell layer of the DG (E). In the MOB, the “With Lamb” group showed highest length of dendritic trees and more nodes on BrdU+/DCX+ cells than in the two other groups (A–B). In the DG no significant difference was found (D–E). Data are represented as median and interquartile ranges. * p ≤ 0.05, ** p < 0.01. •: extreme value. (C) Representative illustration of dendritic lengths of DCX+/BrdU+ cells measured in the granular layer of the MOB in the “Virgin”, the “No Lamb” and the “With Lamb” groups. Scales bars: 10 µm.
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Figure 4: Effects of parturition and/or interactions with the young on the dendritic tree of neuroblasts. (A, D) Length of dendritic processes of BrdU+/DCX+ cells (16–18 cells/animal) in the granular layer of the MOB (A) and in the granular cell layer of the DG (D) in the “Virgin” (n = 6), the “No Lamb” (n = 6) and the “With Lamb” (n = 5) groups. (B, E) Percentage of BrdU+/DCX+ cells which displayed one or more nodes in each group in the granular layer of the MOB (B) and in the granular cell layer of the DG (E). In the MOB, the “With Lamb” group showed highest length of dendritic trees and more nodes on BrdU+/DCX+ cells than in the two other groups (A–B). In the DG no significant difference was found (D–E). Data are represented as median and interquartile ranges. * p ≤ 0.05, ** p < 0.01. •: extreme value. (C) Representative illustration of dendritic lengths of DCX+/BrdU+ cells measured in the granular layer of the MOB in the “Virgin”, the “No Lamb” and the “With Lamb” groups. Scales bars: 10 µm.

Mentions: To determine the development of the newborn neuroblasts in the different groups, the number of nodes and the length of the dendritic arbor were measured in 16–18 BrdU+/DCX+ cells per ewe in the GCL of the MOB and of the DG. Each BrdU+/DCX+ cell was analyzed with confocal laser scanning microscope (LSM 700, Zeiss, Germany), in its entire Z-axis with 0.5 µm step interval, using x63 oil immersion objective to measure the length between the cell body to the end of the longest process. Total length of the dendritic tree was obtained by summing the length of all processes of each BrdU+/DCX+ cell. The number of nodes was obtained by counting the number of occurrences of branch points in the dendritic arbor. Interestingly, these newborn cells seemed to be at an early stage of maturation as most of them displayed only one process. Thus, the population of BrdU+/DCX+ was separated in two categories depending on the number of nodes and the percentage of cells with no nodes (one process, less mature) or with one or more nodes (two or more processes, more mature) was calculated (Figures 4B–E). Ambiguous cases were further analyzed using a semiautomatic neuron tracing system Imaris (Bitplane, USA).


Interactions with the young down-regulate adult olfactory neurogenesis and enhance the maturation of olfactory neuroblasts in sheep mothers.

Brus M, Meurisse M, Keller M, Lévy F - Front Behav Neurosci (2014)

Effects of parturition and/or interactions with the young on the dendritic tree of neuroblasts. (A, D) Length of dendritic processes of BrdU+/DCX+ cells (16–18 cells/animal) in the granular layer of the MOB (A) and in the granular cell layer of the DG (D) in the “Virgin” (n = 6), the “No Lamb” (n = 6) and the “With Lamb” (n = 5) groups. (B, E) Percentage of BrdU+/DCX+ cells which displayed one or more nodes in each group in the granular layer of the MOB (B) and in the granular cell layer of the DG (E). In the MOB, the “With Lamb” group showed highest length of dendritic trees and more nodes on BrdU+/DCX+ cells than in the two other groups (A–B). In the DG no significant difference was found (D–E). Data are represented as median and interquartile ranges. * p ≤ 0.05, ** p < 0.01. •: extreme value. (C) Representative illustration of dendritic lengths of DCX+/BrdU+ cells measured in the granular layer of the MOB in the “Virgin”, the “No Lamb” and the “With Lamb” groups. Scales bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927075&req=5

Figure 4: Effects of parturition and/or interactions with the young on the dendritic tree of neuroblasts. (A, D) Length of dendritic processes of BrdU+/DCX+ cells (16–18 cells/animal) in the granular layer of the MOB (A) and in the granular cell layer of the DG (D) in the “Virgin” (n = 6), the “No Lamb” (n = 6) and the “With Lamb” (n = 5) groups. (B, E) Percentage of BrdU+/DCX+ cells which displayed one or more nodes in each group in the granular layer of the MOB (B) and in the granular cell layer of the DG (E). In the MOB, the “With Lamb” group showed highest length of dendritic trees and more nodes on BrdU+/DCX+ cells than in the two other groups (A–B). In the DG no significant difference was found (D–E). Data are represented as median and interquartile ranges. * p ≤ 0.05, ** p < 0.01. •: extreme value. (C) Representative illustration of dendritic lengths of DCX+/BrdU+ cells measured in the granular layer of the MOB in the “Virgin”, the “No Lamb” and the “With Lamb” groups. Scales bars: 10 µm.
Mentions: To determine the development of the newborn neuroblasts in the different groups, the number of nodes and the length of the dendritic arbor were measured in 16–18 BrdU+/DCX+ cells per ewe in the GCL of the MOB and of the DG. Each BrdU+/DCX+ cell was analyzed with confocal laser scanning microscope (LSM 700, Zeiss, Germany), in its entire Z-axis with 0.5 µm step interval, using x63 oil immersion objective to measure the length between the cell body to the end of the longest process. Total length of the dendritic tree was obtained by summing the length of all processes of each BrdU+/DCX+ cell. The number of nodes was obtained by counting the number of occurrences of branch points in the dendritic arbor. Interestingly, these newborn cells seemed to be at an early stage of maturation as most of them displayed only one process. Thus, the population of BrdU+/DCX+ was separated in two categories depending on the number of nodes and the percentage of cells with no nodes (one process, less mature) or with one or more nodes (two or more processes, more mature) was calculated (Figures 4B–E). Ambiguous cases were further analyzed using a semiautomatic neuron tracing system Imaris (Bitplane, USA).

Bottom Line: In addition, a morphological analysis was performed by measuring the dendritic arbor of neuroblasts in both structures.We showed that the postpartum period was associated with a decrease in olfactory and hippocampal adult neurogenesis.Our assumption is that fewer new neurons decrease cell competition in the olfactory bulb and enhance maturation of those new neurons selected to participate in the learning of the young odor.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 85, Physiologie de la Reproduction et des Comportements Nouzilly, France ; CNRS, UMR 7247 Nouzilly, France ; Université François Rabelais Tours, France ; IFCE Nouzilly, France.

ABSTRACT
New neurons are continuously added in the dentate gyrus (DG) and the olfactory bulb of mammalian brain. While numerous environmental factors controlling survival of newborn neurons have been extensively studied, regulation by social interactions is less documented. We addressed this question by investigating the influence of parturition and interactions with the young on neurogenesis in sheep mothers. Using Bromodeoxyuridine, a marker of cell division, in combination with markers of neuronal maturation, the percentage of neuroblasts and new mature neurons in the olfactory bulb and the DG was compared between groups of parturient ewes which could interact or not with their lamb, and virgins. In addition, a morphological analysis was performed by measuring the dendritic arbor of neuroblasts in both structures. We showed that the postpartum period was associated with a decrease in olfactory and hippocampal adult neurogenesis. In the olfactory bulb, the suppressive effect on neuroblasts was dependent on interactions with the young whereas in the DG the decrease in new mature neurons was associated with parturition. In addition, dendritic length and number of nodes of neuroblasts were significantly enhanced by interactions with the lamb in the olfactory bulb but not in the DG. Because interactions with the young involved learning of the olfactory signature of the lamb, we hypothesize that this learning is associated with a down-regulation in olfactory neurogenesis and an enhancement of olfactory neuroblast maturation. Our assumption is that fewer new neurons decrease cell competition in the olfactory bulb and enhance maturation of those new neurons selected to participate in the learning of the young odor.

No MeSH data available.


Related in: MedlinePlus