GABAergic neurons in inferior colliculus of the GAD67-GFP knock-in mouse: Electrophysiological and morphological properties

Abstract

Utilizing slice preparations of GAD67-GFP knock-in mouse, in which GABAergic neurons are specifically labeled with GFP fluorescence, we studied electrophysiological characteristics of GABAergic neurons of IC by whole-cell patch clamp-recording combined with biocytin-intracellular-staining techniques. GABAergic neurons of IC fell into two distinct firing types; (1) tonic type neurons and (2) transient (phasic) type neurons. Tonic type neurons showed regularly repetitive discharge pattern in response to a long depolarizing current pulse (200 ms), and transient type neurons showed spike discharges just at the onset of current pulse. Most of neurons of both types showed depolarizing sag in response to hyperpolarizing current pulse, which were blocked by 0.1 mM ZD7288 (Ih blocker). All two types of tonic neurons showed an AHP, which was blocked by Cd2+ (0.1 mM) and high concentration of apamin (2 microM). One of tonic type neurons (BP) revealed a long delay in spike onset or a longer first spike interval when they were stimulated from hyperpolarized potentials. The remaining tonic neurons (RS) did not show this property. Tonic type neurons were distributed in all region of IC. Morphologically, they were not identical; heterogeneous in somatic diameter, dendritic field size and its orientation. One of transient type neurons (Th-) revealed an AHP after the spike. The other transient type neurons (Th+) showed a depolarization hump after the spike, which were blocked by 0.1-0.2 mM Ni2+. Th+ type neurons were found only in the dorsolateral region of IC, having small dendritic field. Th+ type neurons are likely to be a distinct, homogenous group of GABAergic neuron in IC.

Astrocytes Control the Development of the Migration-Promoting Vasculature Scaffold in the Postnatal Brain via VEGF Signaling

“…C57BL/6 mice (3,7,14,21, and 60 d old; Charles River) and GAD67-green fluorescent protein (GFP) (Ono et al, 2005) and glial fibrillary acidic protein (GFAP)-GFP (The Jackson Laboratory) transgenic mice were used. Animals of either sex were used for 3-to 21-d-old mice, and only males were used for the adult animals.…”

The μ-opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus

“…We used a transgenic mouse expressing EGFP under the control of the endogenous promoter for GAD67, a synthetic enzyme for GABA. In contrast to the commercially available "GIN" mouse, which only expresses GFP in a particular subset of rNST GABAergic neurons (Travers et al 2007;Wang and Bradley 2010a), this GAD67-GFP knockin strain has been shown to produce EGFP in virtually all cells expressing GAD67 (Brown et al 2008;Kaneko et al 2008;Ono et al 2005;Tamamaki et al 2003), allowing for a more complete identification of GABAergic neurons in the NTS. Because of reports that monosynaptic inputs to GABAergic neurons in the rNST may diminish during development in rat (Wang et al 2012) but evidence for presynaptic inhibition of monosynaptic vagal inputs to cNST GABAergic neurons in mature as well as young mice (Glatzer et al 2007), we included both mouse pups (P14 -18) and adult mice (6 -11 wk) in our study.…”

The Neurochemically Diverse Intermedius Nucleus of the Medulla as a Source of Excitatory and Inhibitory Synaptic Input to the Nucleus Tractus Solitarii

“…First, the different transgenic mouse strains we used to identify GADexpressing neurons appear to reliably label GABAergic neurons (Tamamaki et al, 2003;Lopez-Bendito et al, 2004;Marowsky et al, 2005;Zhang et al, 2006) but may not label all GAD neurons in every CNS region. Nevertheless, the GAD67-GFP mouse line was created using homologous recombination, and as such, all neurons that express GAD67 would be expected to drive the expression of GFP (Tamamaki et al, 2003), and this situation has been described in several CNS regions (Ono et al, 2005) including the brainstem [Li et al (2005), their Fig. 2].…”