Expression patterns of NKCC1 in neurons and non-neuronal cells during cortico-hippocampal development

Abstract

The Na-K-2Cl cotransporter NKCC1 is widely expressed in cells within and outside the brain. However, our understanding of its roles in brain functions throughout development, as well as in neuropsychiatric and neurological disorders, has been severely hindered by the lack of reliable data on its developmental and (sub)cellular expression patterns. We provide here the first properly controlled analysis of NKCC1 protein expression in various cell types of the mouse brain using custom-made antibodies and an NKCC1 knock-out validated immunohistochemical procedure, with parallel data based on advanced mRNA approaches. NKCC1 protein and mRNA are expressed at remarkably high levels in oligodendrocytes. In immature neurons, NKCC1 protein was located in the somata, whereas in adult neurons, only NKCC1 mRNA could be clearly detected. NKCC1 immunoreactivity is also seen in microglia, astrocytes, developing pericytes, and in progenitor cells of the dentate gyrus. Finally, a differential expression of NKCC1 splice variants was observed, with NKCC1a predominating in non-neuronal cells and NKCC1b in neurons. Taken together, our data provide a cellular basis for understanding NKCC1 functions in the brain and enable the identification of major limitations and promises in the development of neuron-targeting NKCC1-blockers.

Heterogeneous subpopulations of GABAAR-responding neurons coexist across neuronal network scales and developmental stages in health and disease

“…Furthermore, our results on the modulation of the GABA A R-dependent effect of diazepam (both on in vivo Ca 2+ imaging and anxiety behavior) by systemic bumetanide pretreatment indicate that NKCC1 has a role in mediating GABAergic responses in the brain in vivo , also in the light of the cell-type-specific expression patterns of NKCC1 in the brain. 81 Our results on the modulation of diazepam effect by systemic bumetanide pretreatment are thus very relevant, considering the poor blood-brain barrier penetration of bumetanide, which at times has cast doubts on its chloride-dependent (and thus GABA-dependent) mechanism of action. 82 , 83 , 84 , 85 …”

Heterogeneous subpopulations of GABAAR-responding neurons coexist in physiological and pathological mature neuronal networks at increasing scales of complexity

“…1B). Interestingly, while the initial developmental drop (2)(3)(4)(5)(6)(7) in the population of neurons with depolarizing GABA-mediated responses in Ts65Dn neurons was similar to that of WT neurons, the population of Ts65Dn neurons with depolarizing GABA responses was significantly greater at later time points (15 and 21 DIV; Fig. 1B).…”

“…This makes inward the flow of negatively charged chloride ions through the receptor; thus, GABAAR signalling is hyperpolarizing and inhibitory 1,2,3 in adult animals. Conversely, during neuronal development (until the first or second postnatal week in rodents), GABA exerts a depolarizing and possibly excitatory effect due to low expression of KCC2 in immature neurons, which leads to a high [Cl -]i and an outward flow of Clthrough GABAARs 2,4 . Depolarizing GABAergic signalling during development is fundamental for organizing early patterns of neuronal activity by enabling neurons to fire and thus form their first synaptic connections 5,6,7,8,9,10,11 .…”

SPAK inhibitor ZT‐1a attenuates reactive astrogliosis and oligodendrocyte degeneration in a mouse model of vascular dementia

“…Therefore, further study is required to assess the effects of ZT-1a during the advanced stage of VCID and to establish the optimal doses of ZT-1a. It is important to note that SPAK and NKCC1 proteins are widely expressed in the CNS both in glia and neurons, 39 and play an important role in the synaptic transmission, blood-cerebrospinal fluid barrier integrity, inflammation, as well as brain injury. [40][41][42] BCAS-induced memory impairment is not only associated with WML but also hippocampal neurodegeneration.…”