Cracking down on inhibition: selective removal of GABAergic interneurons from hippocampal networks.
Inhibitory (GABAergic) interneurons entrain assemblies of excitatory principal neurons to orchestrate information processing in the hippocampus. Disrupting the dynamic recruitment as well as the temporally precise activity of interneurons in hippocampal circuitries can manifest in epileptiform seizures, and impact specific behavioral traits. Despite the importance of GABAergic interneurons during information encoding in the brain, experimental tools to selectively manipulate GABAergic neurotransmission are limited. Here, we report the selective elimination of GABAergic interneurons by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies (SAVAs) in vitro as well as in the mouse and rat hippocampus in vivo. We demonstrate the selective loss of GABAergic--but not glutamatergic--synapses, reduced GABA release, and a shift in excitation/inhibition balance in mixed cultures of hippocampal neurons exposed to SAVAs. We also show the focal and indiscriminate loss of calbindin(+), calretinin(+), parvalbumin/system A transporter 1(+), somatostatin(+), vesicular glutamate transporter 3 (VGLUT3)/cholecystokinin/CB(1) cannabinoid receptor(+) and neuropeptide Y(+) local-circuit interneurons upon SAVA microlesions to the CA1 subfield of the rodent hippocampus, with interneuron debris phagocytosed by infiltrating microglia. SAVA microlesions did not affect VGLUT1(+) excitatory afferents. Yet SAVA-induced rearrangement of the hippocampal circuitry triggered network hyperexcitability associated with the progressive loss of CA1 pyramidal cells and the dispersion of dentate granule cells. Overall, our data identify SAVAs as an effective tool to eliminate GABAergic neurons from neuronal circuits underpinning high-order behaviors and cognition, and whose manipulation can recapitulate pathogenic cascades of epilepsy and other neuropsychiatric illnesses.
Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano, I-20129 Milan, Italy.
Flavia
F
Antonucci
Alán
A
Alpár
Johannes
J
Kacza
Matteo
M
Caleo
Claudia
C
Verderio
Alice
A
Giani
Henrik
H
Martens
Farrukh A
FA
Chaudhry
Manuela
M
Allegra
Jens
J
Grosche
Dominik
D
Michalski
Christian
C
Erck
Anke
A
Hoffmann
Tibor
T
Harkany
Michela
M
Matteoli
Wolfgang
W
Härtig
D000818:Animals; D064032:Calbindin 2; D064026:Calbindins; D016923:Cell Death / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D059330:GABAergic Neurons / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D007395:Interneurons / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009415:Nerve Net / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D009433:Neural Inhibition / Q000235:genetics; D010587:Phagocytosis / Q000235:genetics; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000235:genetics
C576511:Calb2 protein, mouse; C576512:Calb2 protein, rat; D064032:Calbindin 2; D064026:Calbindins; D064030:S100 Calcium Binding Protein G