, 2002) DBI mRNA is widely expressed throughout

the brai

, 2002). DBI mRNA is widely expressed throughout

the brain, including the thalamus (Lein et al., 2007). Previous immunohistochemical studies have observed varying profiles of protein expression for DBI and fragment peptides in the CNS of various species (Tonon et al., 1990; Slobodyansky et al., 1992; Lihrmann et al., 1994), likely due to use of different antisera and other methodological differences, but in some cases higher expression was observed in nRT (Alho et al., 1985, 1989). We therefore hypothesized that DBI may exert endogenous effects within the thalamus, thereby modulating seizure click here susceptibility. Here, we investigate this by comparing inhibitory transmission, effects of BZ site blockade, and

PD0332991 seizure profiles in wild-type (WT), α3(H126R), and nm1054 (new mutation 1054) mice, which harbor a 400 kb deletion on chromosome 1 that includes the Dbi gene ( Ohgami et al., 2005). Furthermore, we tested the ability of viral transduction of DBI into the thalamus to rescue the effect of the nm1054 mutation. We also examine allosteric modulation of responses to focal GABA uncaging in “sniffer” patches pulled from VB neurons and placed back in the slice in either VB or nRT. Our results provide novel functional evidence for the constitutive presence of endogenous BZ binding site ligands (“endozepines”) that mimic

the PAM actions of BZs specifically within nRT. The primary PAM effect of BZs on GABAARs is to increase the duration of inhibitory postsynaptic currents (IPSCs) (Mody et al., 1994). Therefore, we focused on this parameter in assessing whether endogenous BZ site PAMs alter intrathalamic inhibition. We recorded spontaneous IPSCs (sIPSCs) and evoked monosynaptic intra-nRT IPSCs (eIPSCs) in nRT cells from C57BL/6 WT and α3(H126R) mice. As in Resminostat previous reports (Huntsman and Huguenard, 2000), sIPSC duration progressively decreased through early development, reaching maturity by P20; therefore, all experiments used age-matched comparisons. α3(H126R) cells in both young and adult mice showed briefer sIPSCs (p < 0.001) and eIPSCs (p < 0.01) compared to WT (Figures 1A–1D and S1; Table S1). The decay phase of sIPSCs could be best described by a double exponential function, and both fast and slow decay time constants were shortened by the α3(H126R) mutation, while the relative contribution of fast and slow decay was unaffected (Table S1). This suggests that both components of IPSC decay are dependent on BZ-sensitive GABAARs. There was no difference in unitary conductance or numbers of channels mediating events as revealed by nonstationary variance analysis (Sigworth, 1980; De Koninck and Mody, 1994; Schofield and Huguenard, 2007; Figures 1E–1G).

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