Figure 6.

Chronic intermittent hypoxia (IH) reduces mature spine formation of CA1 pyramidal neurons and interneurons. (A) Typical morphologies of individual pyramidal neurons in CA1 region revealed by Golgi staining on day 1, 14 and 21. Scale bar: 50 μm. The higher magnification pictures shown in the lower panels allowed quantification of spine density and classification of individual spines. Black arrowheads indicate stubby spines; white arrowheads indicate thin spines; arrows indicate mushroom spines Scale bar: 4 μm. (B) Quantification analysis from 54 dendrites revealed no significant difference between day 1, 14 and 21 in terms of overall spine density (top left), stubby spine density (top right) and thin spine density (bottom left). However, the density of the mushroom spine was significantly altered (bottom right). Meanwhile, post-hoc Newman-Keuls's test revealed mushroom spine density was decreased significantly in 2 weeks IH treatment, which could recover on day 21 (right panel). ***P < 0.001. (C) Typical morphologies of individual interneurons in CA1 region revealed by Golgi staining on day 1, 14 and 21. Scale bar: 50 μm. Higher magnification pictures are shown in the lower panels. Scale bar: 4 μm. (D) Quantification of data from 45 dendrites showed that there was significantly difference in the overall spine density (top left), thin spine density (bottom left) and mushroom spine (bottom right) except stubby spine density (top right). Post-hoc Newman-Keuls's test revealed clear reduction of overall spine density after 2 weeks of IH treatment, compared with day 1, as well as the densities of thin spine and mushroom spine. These changes were not recoverable even after 1 week of normoxia treatment, **P < 0.01, ***P < 0.001.