Related Experiment Videos
Response of amoeboid microglial cells to chloroquine injections in postnatal rats
Insights
Chloroquine treatment in young rats causes temporary changes in amoeboid microglial cells, increasing vacuoles and lysosomes. These effects on microglial cells are reversible after drug discontinuation.
Area of Science:
- Neuroscience
- Cell Biology
- Immunology
Background:
- Microglia are the resident immune cells of the central nervous system.
- Amoeboid microglia are a developmental stage involved in brain maturation and immune surveillance.
- Chloroquine is an antimalarial drug with known immunomodulatory effects.
Purpose of the Study:
- To investigate the effects of chloroquine on developing amoeboid microglial cells in postnatal rats.
- To examine the ultrastructural and immunohistochemical changes in microglia following chloroquine administration.
- To determine the reversibility of chloroquine-induced microglial alterations.
Main Methods:
- Postnatal day 1 rats received daily intraperitoneal injections of chloroquine for 6 days.
- Animals were sacrificed at 7, 14, and 21 days of age for analysis.
- Electron microscopy and immunohistochemistry (using antibodies OX-42, ED1, OX-18, OX-6, and Griffonia simplicifolia isolectin) were employed.
Main Results:
- At 7 days, chloroquine-induced amoeboid microglia showed increased vacuoles and lysosomes, with comparable cell numbers and OX-42 immunoreactivity to controls.
- At 14 days, microglia appeared hypertrophic with enhanced OX-42 immunoreactivity and massive lysosomes; isolectin binding indicated plasma membrane internalization into lysosomes.
- By 21 days, microglial features and immunoreactivity returned to control levels, indicating reversibility.
Conclusions:
- Chloroquine significantly alters the morphology and lysosomal content of developing amoeboid microglial cells.
- The observed effects of chloroquine on microglia are transient and reversible upon cessation of the drug.
- This study highlights the dynamic response and recovery capacity of the developing microglial population.
Abstract:
One-day-old postnatal rats were given single daily intraperitoneal injections of chloroquine for 6 successive days and sacrificed at 7, 14 and 21 days of age. In rats killed at 7 days of age, the amoeboid microglial cells in the corpus callosum above the lateral ventricles showed a marked increase in vacuoles and lysosomes by electron microscopy. Immunohistochemical study showed that the number and OX-42 immunoreactivity of these cells were comparable to those of the control rats. At 14 days, the immunoreactive amoeboid microglia appeared hypertrophic and their immunoreactivity was noticeably enhanced when compared with the ramified cells in the controls. Ultrastructurally the amoeboid microglial cells in the chloroquine-treated cells showed massive lysosomes. At 21 days, the immunoreactivity of amoeboid microglial cells and their lysosomes were comparable to those of the controls. Results with the antibodies ED1 and OX-18 paralleled those with OX-42 in terms of the temporal change of immunoreactivity and external morphology of amoeboid microglia. OX-6 immunoreactive cells were not observed in both groups of rats. With the isolectin, Griffonia simplicifolia, the reaction product which was normally confined to the plasma membrane of amoeboid microglia was also localized in vacuoles and the massive lysosomes in the chloroquine-injected rats suggesting the internalization of plasma membrane and its sequestration in the lysosomes. It is concluded from this study that although amoeboid microglial cells responded vigorously to chloroquine, its effects are reversible since with the discontinuance of the drug and prolongation of survival interval, the cells regained their normal features.