Anti-GABRA5 polyclonal antibody

Establishing the pattern of expression of transmitters and peptides as well as their receptors in different neuronal types is crucial for understanding the circuitry in various regions of the brain. Previous studies have demonstrated that the transmitter and peptide phenotypes in mouse dorsal spinal cord neurons are determined by the transcription factors Tlx1/3 and Ptf1a. Here we show that these transcription factors also determine the expression of two distinct sets of transmitter and peptide receptor genes in this region. We have screened the expression of 78 receptor genes in the spinal dorsal horn by in situ hybridization. We found that receptor genes Gabra1, Gabra5, Gabrb2, Gria3, Grin3a, Grin3b, Galr1, and Npy1r were preferentially expressed in Tlx3-expressing glutamatergic neurons and their derivatives, and deletion of Tlx1 and Tlx3 resulted in the loss of expression of these receptor genes. Furthermore, we obtained genetic evidence that Tlx3 uses distinct pathways to control the expression of receptor genes. We also found that receptor genes Grm3, Grm4, Grm5, Grik1, Grik2, Grik3, and Sstr2 were mainly expressed in Pax2-expressing GABAergic neurons in the spinal dorsal horn, and their expression in this region was abolished or markedly reduced in Ptf1a and Pax2 deletion mutant mice. Together, our studies indicate that Tlx1/3 and Ptf1a, the key transcription factors for fate determination of glutamatergic and GABAergic neurons in the dorsal spinal cord, are also responsible for controlling the expression of two distinct sets of transmitter and peptide receptor genes.

BACKGROUND: General anesthetics cause cognitive deficits that persist much longer than would be expected on the basis of their pharmacokinetics. The cellular mechanisms underlying these postanesthetic cognitive deficits remain unknown. gamma-Aminobutyric acid type A (GABA(A)) receptors are principal targets for most anesthetics. In particular, the alpha 5GABA(A) receptor subtype has been implicated in acute memory blockade during anesthesia and memory deficits in the early postoperative period. We first sought to determine whether working memory and short-term recognition memory are impaired after isoflurane anesthesia. The second aim of the study was to determine whether memory deficits after isoflurane can be reversed by inhibiting a5GABAA receptors. We also sought to determine whether the expression of alpha 5GABA(A) receptors is necessary for the development of memory dysfunction after isoflurane. Lastly, the effect of sevoflurane on memory was studied. METHODS: Wild-type and alpha 5GAB(A), receptor null-mutant (Gabra5-/-) mice were treated with isoflurane (1.3%; 1 minimum alveolar concentration [MAC]) or sevoflurane (2.3%; 1 MAC) or vehicle gas for 1 hour. Memory performance was assessed with a novel object recognition task. Mice were trained on the recognition task either 24 hours or 72 hours after isoflurane anesthesia. Working memory and short-term memory were tested 1 minute and 1 hour after training, respectively. To determine whether inhibition of alpha 5GABA(A) receptors reverses memory deficits, we treated a subset of mice with L-655,708 (0.35 mg/kg or 0.7 mg/kg) 23.5 hours after isoflurane and 30 minutes before behavioral training. RESULTS: Short-term memory was impaired in wild-type mice 24 hours after isoflurane as evidenced by a decrease in the discrimination ratio (control 0.66 +/- 0.03 vs isoflurane 0.51 +/- 0.03, P = 0.0005). In contrast, working memory was not impaired by isoflurane (control 0.68 +/- 0.05 vs isoflurane 0.67 +/- 0.04, P = 0.979). The deficit in short-term memory was fully reversed by L-655,708 (effect of isoflurane x L-655,708, F-2,F-102 = 3.59, P = 0.032; isoflurane 0.51 +/- 0.03 vs isoflurane + L-655,708 at 0.35 mg/kg 0.67 +/- 0.03, P < 0.05). By 72 hours, the deficits in short-term memory resolved spontaneously (control 0.65 +/- 0.05 vs isoflurane 0.60 +/- 0.04, P = 0.441). Gabra5-/- mice showed no short-term memory deficits 24 hours after isoflurane (effect of isoflurane F-1,F-47 = 0.375, P = 0.544). Sevoflurane also caused memory deficits 24 hours after anesthesia, as evidence by a reduction in the discrimination ratio (control 0.63 +/- 0.02 vs sevoflurane 0.53 +/- 0.03, P = 0.039). CONCLUSIONS: Inhalational anesthetics cause deficits in anterograde recognition memory. This proof-of-concept study shows that alpha 5GABA(A) receptors are necessary for the development of postanesthetic deficits in recognition memory and that these receptors can be targeted to restore memory even after the anesthetic has been eliminated. (Anesth Analg 2012;114:845-55)