Comparison of three common inbred mouse strains reveals substantial
differences in hippocampal GABAergic interneuron populations and in
vitro network oscillations
Abstract
A major challenge in neuroscience is to pinpoint neurobiological
correlates of specific cognitive and neuropsychiatric traits. At the
mesoscopic level, promising candidates for establishing such connections
are brain oscillations that can be robustly recorded as local field
potentials with varying frequencies in the hippocampus in vivo and in
vitro. Inbred mouse strains show natural variation in hippocampal
synaptic plasticity (e.g., long-term potentiation), a cellular correlate
of learning and memory. However, their diversity in expression of
different types of hippocampal network oscillations has not been fully
explored. Here, we investigated hippocampal network oscillations in
three widely used inbred mouse strains: C57BL/6J (B6J), C57BL/6NCrl
(B6N) and 129S2/SvPasCrl (129) with the particular aim to identify
common oscillatory characteristics in inbred mouse strains that show
aberrant emotional/cognitive behaviour (B6N and 129) and compare them to
“control” B6J strain. First, we detected higher gamma oscillation
power in the hippocampal CA3 of both B6N and 129 strains. Second, an
increased incidence of hippocampal sharp wave-ripple (SW-R) transients
was evident in these strains. Third, we observed prominent differences
in the densities of distinct interneuron types and CA3 associative
network activity which are indispensable for sustainment of mesoscopic
network oscillations. Together, these results supports the notion that
in vitro hippocampal network oscillations, similar to classical
plasticity read-outs measured in hippocampal slices, can be used as
robust reductionist models to study electrophysiological correlates of
emotional and cognitive phenotypes. Importantly, we add further evidence
to profound physiological differences among inbred mouse strains
commonly used in neuroscience research.