Sodium bicarbonate cotransporter NBCn1/Slc4a7 affects locomotor activity and hearing in mice

• Published in: Behavioural brain research Vol. 401; p. 113065
• Main Authors: Choi, Inyeong, Beedholm, Kristian, Dam, Vibeke S., Bae, Seong-Ho, Noble, Donald J., Garraway, Sandra M., Aalkjaer, Christian, Boedtkjer, Ebbe
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.03.2021
• Subjects: Acid base transporter; Animals; Behavior, Animal - physiology; Evoked Potentials, Auditory - genetics; Exploratory Behavior - physiology; Female; Hearing; Hearing Loss - genetics; Knockout mice; Locomotion - genetics; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mouse behavior; Retina - metabolism; Sodium bicarbonate transporter; Sodium-Bicarbonate Symporters - genetics; Sodium-Bicarbonate Symporters - physiology; Spatial Learning - physiology; Vision; Vision Disorders - genetics; Acid base transporter; Knockout mice; Hearing; Mouse behavior; Vision; Sodium bicarbonate transporter
• DOI: 10.1016/j.bbr.2020.113065
• ISSN: 0166-4328

•NBCn1 KO mice show reduced locomotor activity to a novel environment.•Anxiety-related behaviors and spatial learning are normal in NBCn1 KO mice.•Aged KO mice develop hearing loss while maintaining normal vision.•An alternatively transcribed NBCn1 variant is expressed in KO mouse retinas. Despite a widespread expression pattern in the central nervous system, the role of the sodium bicarbonate cotransporter NBCn1/Slc4a7 has not been investigated for locomotor activity, emotion and cognition. Here, we addressed the behavioral consequences of NBCn1 knockout and evaluated hearing and vision that are reportedly impaired in an earlier line of NBCn1 knockout mice and may contribute to behavioral changes. In a circular open field, the knockout mice traveled a shorter distance, especially in the periphery of the chamber, than wildtype littermates. The knockout mice also traveled a shorter total distance in a home cage-like open field. Rearing and grooming behaviors were reduced. The knockout and control mice displayed similar time spent and number of open and closed arms in the elevated plus maze test, indicating negligible change in anxiety. In the Morris water maze test, both groups of mice learned the location of an escape platform within comparable time on the training trials and showed similar platform identification on the probe trial. The knockout mice maintained normal visual responses in the optokinetic drum and produced evoked potentials in response to light stimuli. However, these mice failed to produce auditory evoked potentials. qPCR revealed a robust expression of an alternatively transcribed NBCn1 variant in the knockout mouse retina. These results indicate that NBCn1 deletion leads to reduced locomotor activity in mice by affecting their exploratory behaviors or emotionality. The deletion also causes hearing loss, but its effect on vision varies between different lines of knockout mice.