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Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus

Contrasting distribution of CCK- and PV-GABA cells in the temporal cortex. (Top) Sections of the temporal cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the temporal cortex. PV-GABA cells are significantly more numerous in auditory cortex regions. Ventral to the rhinal fissure, PV-GABA cells become less common and CCK-GABA cells become more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
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Figure 6: Contrasting distribution of CCK- and PV-GABA cells in the temporal cortex. (Top) Sections of the temporal cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the temporal cortex. PV-GABA cells are significantly more numerous in auditory cortex regions. Ventral to the rhinal fissure, PV-GABA cells become less common and CCK-GABA cells become more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.

Mentions: GFP-labeled cells in CCK- and PV-Frepe mice were enumerated in the intermediate regions of the temporal cortex. In our sampling method, we included subdivisions of the auditory cortex (Aud1, AudD, AudV) as well as the temporal association cortex (Tea), ectorhinal cortex (Ect), perirhinal cortex (Prh) and entorhinal cortex (EntDI and EntDL) (Table 1, Figure 6). Two-way ANOVA detected a genotype × brain region interaction on the percentage of GFP-labeled cells [F(7,71) = 14.45, p < 0.0001]. In all subdivisions of the auditory cortex, PV-GABA cells were highly abundant and more numerous than CCK-GABA cells (all ps < 0.05, Figure 6). PV-GABA cell density was much lower outside of the auditory cortex, as observed in other species (McMullen et al., 1994). Interestingly, the transition from the ventral auditory cortex (AudV) into the area of the rhinal fissure (Tea, Ect, and PRh) coincided with an abrupt reduction in PV-GABA cell percentage. Surprisingly, the reverse trend in distribution was observed for CCK-GABA cells, which tended to be more numerous in the Tea, Ect, and PRh areas than in auditory cortex. As a result of these contrasting trends, the percentage count of CCK- and PV-GABA cells was comparable in temporal association areas. In fact, CCK-GABA cell percentage even tended to be higher than PV-GABA cell percentage in the examined subdivisions such as the entorhinal cortex (EntDI, EntDL), though the difference was not significant.


Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Contrasting distribution of CCK- and PV-GABA cells in the temporal cortex. (Top) Sections of the temporal cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the temporal cortex. PV-GABA cells are significantly more numerous in auditory cortex regions. Ventral to the rhinal fissure, PV-GABA cells become less common and CCK-GABA cells become more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585045&req=5

Figure 6: Contrasting distribution of CCK- and PV-GABA cells in the temporal cortex. (Top) Sections of the temporal cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the temporal cortex. PV-GABA cells are significantly more numerous in auditory cortex regions. Ventral to the rhinal fissure, PV-GABA cells become less common and CCK-GABA cells become more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
Mentions: GFP-labeled cells in CCK- and PV-Frepe mice were enumerated in the intermediate regions of the temporal cortex. In our sampling method, we included subdivisions of the auditory cortex (Aud1, AudD, AudV) as well as the temporal association cortex (Tea), ectorhinal cortex (Ect), perirhinal cortex (Prh) and entorhinal cortex (EntDI and EntDL) (Table 1, Figure 6). Two-way ANOVA detected a genotype × brain region interaction on the percentage of GFP-labeled cells [F(7,71) = 14.45, p < 0.0001]. In all subdivisions of the auditory cortex, PV-GABA cells were highly abundant and more numerous than CCK-GABA cells (all ps < 0.05, Figure 6). PV-GABA cell density was much lower outside of the auditory cortex, as observed in other species (McMullen et al., 1994). Interestingly, the transition from the ventral auditory cortex (AudV) into the area of the rhinal fissure (Tea, Ect, and PRh) coincided with an abrupt reduction in PV-GABA cell percentage. Surprisingly, the reverse trend in distribution was observed for CCK-GABA cells, which tended to be more numerous in the Tea, Ect, and PRh areas than in auditory cortex. As a result of these contrasting trends, the percentage count of CCK- and PV-GABA cells was comparable in temporal association areas. In fact, CCK-GABA cell percentage even tended to be higher than PV-GABA cell percentage in the examined subdivisions such as the entorhinal cortex (EntDI, EntDL), though the difference was not significant.

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus