Neural Regeneration Research ›› 2022, Vol. 17 ›› Issue (1): 20-24.

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Dendritic spine density changes and homeostatic synaptic scaling: a meta-analysis of animal studies

Thiago C. Moulin1, 2, *, Danielle Rayêe3, 4, Helgi B. Schiöth1, 5   

  1. 1Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden; 2Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; 3Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; 4Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, NY, USA; 5Institute for Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russia
  • Online:2022-01-05 Published:2021-09-17
  • Contact: Thiago C. Moulin, PhD, thiago.moulin@neuro.uu.se.
  • Supported by:
    This work was supported by scholarships from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil (to TCM and DR); supported by the Kungl Vetenskapssamh Scholarship (Royal Society of Arts and Scientists), provided by Uppsala University, Sweden (to TCM); and supported by the Swedish Research Council and the Swedish Brain Research Foundation (to HBS).

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Abstract: Mechanisms of homeostatic plasticity promote compensatory changes of cellular excitability in response to chronic changes in the network activity. This type of plasticity is essential for the maintenance of brain circuits and is involved in the regulation of neural regeneration and the progress of neurodegenerative disorders. One of the most studied homeostatic processes is synaptic scaling, where global synaptic adjustments take place to restore the neuronal firing rate to a physiological range by the modulation of synaptic receptors, neurotransmitters, and morphology. However, despite the comprehensive literature on the electrophysiological properties of homeostatic scaling, less is known about the structural adjustments that occur in the synapses and dendritic tree. In this study, we performed a meta-analysis of articles investigating the effects of chronic network excitation (synaptic downscaling) or inhibition (synaptic upscaling) on the dendritic spine density of neurons. Our results indicate that spine density is consistently reduced after protocols that induce synaptic scaling, independent of the intervention type. Then, we discuss the implication of our findings to the current knowledge on the morphological changes induced by homeostatic plasticity.

Key words: chronic inhibition, chronic stimulation, dendritic spines, downscaling, excitability, homeostatic plasticity, spine density, synaptic scaling, upscaling