Activating transcription factor 5 (ATF5) is a member of the CREB/ATF family of transcription factors, which is highly expressed in olfactory chemosensory tissues, the main olfactory epithelium and vomeronasal epithelium (VNE) in mice. The vomeronasal sensory neurons in the VNE detect pheromones in order to regulate social behaviors such as mating and aggression; however, the physiological role of ATF5 in the vomeronasal sensory system remains unknown. In this study, we found that the differentiation of mature vomeronasal sensory neurons, assessed by olfactory marker protein expression, was inhibited in ATF5-deficient VNE. In addition, many apoptotic vomeronasal sensory neurons were evident in ATF5-deficient VNE. The vomeronasal sensory neurons consist of two major types of neuron expressing either vomeronasal 1 receptor (V1r)/Gαi2 or vomeronasal 2 receptor (V2r)/Gαo. We demonstrated that the differentiation, survival and axonal projection of V2r/Gαo-type rather than V1r/Gαi2-type vomeronasal sensory neurons were severely inhibited in ATF5-deficient VNE. These results suggest that ATF5 is one of the transcription factors crucial for the vomeronasal sensory formation.

The electrophysiological properties of isolated rat liver cells were studied using the patch clamp method in whole-cell configuration. The membrane potential in isolated hepatocytes was -42 +/- 7 mV (n = 20). The input resistance (Rin) and the time constant (tau m) were 51 +/- 17 M (the range of 34 to 180 M omega) (n = 20) and 4.2 +/- 1.0 msec (the range of 3 to 16.5 ms) (n = 20). Assuming that the specific membrane capacitance is 1 microF/cm2, the membrane resistance and membrane capacitance were 42. +/- 9.0 K omega cm2 and 87 +/- 27 pF. These values indicate that isolated rat hepatocytes are not abnormally permeable or leaky. The current-voltage relationship was linear with no rectification. The depolarizing pulse from the resting potential did not induce fast or slow inward currents even when norepinephrine or high Ca2 (3.6 mM) were applied. This indicates that there is no voltage-sensitive Ca2+ channel in the isolated hepatocytes.

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