. 2021 Mar 8;81(5):568–590. doi: 10.1002/dneu.22814

TABLE 2.

Synaptic elimination under physiological conditions

Age	Region	Molecule	Event	Promote or inhibit	Inhibition method	Measurement	Reference
P15	Hippocampal CA1	CX3CR1	Developmental elimination	Promote	Knockout	Density of PSD95 and spine	Paolicelli et al. (2011)
P5	LGN	C1q (C3)–CR3	Developmental elimination	Promote	Knockout	Engulfment assay for VGluT2 and axon terminal	Schafer et al. (2012)
8–10 wo	Cortex	Cathepsin S	Sleep	Promote	Knockout	Density of spine	Hayashi et al. (2013)
P28	Visual cortex	P2Y12	Ocular dominance	Promote	Knockout	Engulfment assay for GluR1	Sipe et al. (2016)
P28	Visual cortex	CX3CR1	Ocular dominance	No change	Knockout	Ocular dominance index	Lowery et al. (2017)
P28	LGN	CX3CR1	Developmental elimination	No change	Knockout	Overlap area of contralateral and ipsilateral input	Lowery et al. (2017)
P18–20	Hippocampal CA1	TREM2	Developmental elimination	Promote	Knockout	Engulfment assay for PSD95 Density of VGluT1	Filipello et al. (2018)
P5	LGN	CD47‐SIRPα	Developmental elimination	Inhibit	Knockout	Engulfment assay for VGluT2 and axon terminal	Lehrman et al. (2018)
P20, 1–1.5 mo	Hippocampal CA1 Motor cortex	TREM2	Developmental elimination	Inhibit	Knockout	Engulfment assay for PSD95	Jay et al. (2019)
10–12 wo	Hippocampal CA1	C1q (C3)–CR3	Learning	Inhibit	CD55	Engulfment assay for mCherry used to label neurons	Wang et al. (2020)
P5	LGN	PS‐GPR56 S4	Developmental elimination	Promote	Knockout	Engulfment assay for axon terminal	Li et al. (2020)
P10, 21	Hippocampal CA1	PS‐GPR56 S4	Developmental elimination	Promote	Knockout	Density of colocalization of VGluT2 and Homer1	Li et al. (2020)
P5	LGN	PS	Developmental elimination	Promote	Annexin V	Frequency of mEPSCs of primary hippocampal neuron	Scott‐Hewitt et al. (2020)
P10	Hippocampal CA1	PS	Developmental elimination	Promote	Annexin V	Frequency of mEPSCs of primary hippocampal neuron	Scott‐Hewitt et al. (2020)
P10	LGN	SRPX2	Developmental elimination	Inhibit	Knockout	Engulfment assay for axon terminal	Cong et al. (2020)
P60	Somatosensory cortex layer IV	SRPX2	Developmental elimination	Inhibit	Knockout	Engulfment assay for axon terminal	Cong et al. (2020)

Abbreviations: C1q, complement component 1q; C3, complement component 3; CD47, cluster of differentiation 47; CR3, complement receptor 3; CX3CR1, CX3C chemokine receptor 1; GPR56 S4, G protein‐coupled receptor 56 isoform 4; LGN, lateral geniculate nucleus; mEPSC, miniature excitatory postsynaptic currents; mo, month old; P, postnatal day; PS, phosphatidylserine; PSD95, postsynaptic density protein 95; SIRPα, signal regulatory protein α; SRPX2, sushi repeat protein X‐linked 2; TREM2, triggering receptor expressed on myeloid cells 2; VGluT1, vesicular glutamate transporter 1; VGluT2, vesicular glutamate transporter 2; wo, week‐old.