Exp Neurobiol.  2018 Oct;27(5):419-436. 10.5607/en.2018.27.5.419.

Chronic Treatment with Combined Chemotherapeutic Agents Affects Hippocampal Micromorphometry and Function in Mice, Independently of Neuroinflammation

Affiliations
  • 1College of Veterinary Medicine and BK21Plus Project Team, Chonnam National University, Gwangju 61186, Korea. moonc@chonnam.ac.kr
  • 2Primate Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup 56216, Korea.
  • 3Department of Veterinary Anatomy, College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea.
  • 4Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea.
  • 5K-herb Research Center, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
  • 6Department of Physiology and Neuroscience Program, Michigan State University, MI 48824, USA.
  • 7Department of Anatomy, School of Medicine and Institute for Environmental Science, Wonkwang University, Iksan 54538, Korea. yangm@wku.ac.kr

Abstract

Chemotherapeutic agents induce long-term side effects, including cognitive impairment and mood disorders, particularly in breast cancer survivors who have undergone chemotherapy. However, the precise mechanisms underpinning chemotherapy-induced hippocampal dysfunction remain unknown. In this study, we investigated the detrimental effects of chronic treatment with a combination of adriamycin and cyclophosphamide (AC) on the neuronal architecture and functions of the hippocampi of female C57BL/6 mice. After chronic AC administration, mice showed memory impairment (measured using a novel object recognition memory task) and depression-like behavior (measured using the tail suspension test and forced swim test). According to Golgi staining, chronic AC treatment significantly reduced the total dendritic length, ramification, and complexity as well as spine density and maturation in hippocampal neurons in a sub-region-specific manner. Additionally, the AC combination significantly reduced adult neurogenesis, the extent of the vascular network, and the levels of hippocampal angiogenesis-related factors. However, chronic AC treatment did not increase the levels of inflammation-related signals (microglial or astrocytic distribution, or the levels of pro-inflammatory cytokines or M1/M2 macrophage markers). Thus, chronic AC treatment changed the neuronal architecture of the adult hippocampus, possibly by reducing neurogenesis and the extent of the vasculature, independently of neuroinflammation. Such detrimental changes in micromorphometric parameters may explain the hippocampal dysfunction observed after cancer chemotherapy.

Keyword

Chemotherapy; Hippocampus; Neurogenesis; Neuroinflammation; Neuronal architecture; Vasculature

MeSH Terms

Adult
Animals
Breast Neoplasms
Cognition Disorders
Cyclophosphamide
Cytokines
Doxorubicin
Drug Therapy
Female
Hindlimb Suspension
Hippocampus
Humans
Macrophages
Memory
Mice*
Mood Disorders
Neurogenesis
Neurons
Spine
Survivors
Cyclophosphamide
Cytokines
Doxorubicin
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