Angiotensin II Receptor Signaling in the Hypothalamic-Pituitary-Adrenal Axis and Spleen After Spinal Cord Injury Depends on the Sympathetic Innervation Integrity

Figures

• 

• 

  Fig. 1. Morphological and morphometric changes of the adrenal gland during long-term survival (1–28 days post-injury) after low-thoracic (Th9) injury. A Representative images of the adrenal gland demonstrating transient discoloration and enlargement after spinal cord lesion. Scale bar = 1 mm. B Morphometric analysis of absolute adrenal gland volume determined using the Cavalieri’s stereological method. Data are expressed as mean ± SEM. Sample sizes: intact control (n = 5); SCI: 1 dpi (n = 7); 3, 21, and 28 dpi (n = 6); 7 dpi (n = 8); 14 dpi (n = 5). C Post-traumatic changes in adrenal gland weight. Data are expressed as mean ± SEM. Sample sizes: intact control (n = 12); SCI: 1, 14, 21, and 28 dpi (n = 10); 3 dpi (n = 9); 7 dpi (n = 8); sham-operated control: 1, 3, 7, and 21 dpi (n = 9); 14 and 28 dpi (n = 10). *p < 0.05, **p < 0.01 vs. intact control; #p < 0.05 vs. sham-operated control

• 

  Fig. 2. Alterations in absolute volume of adrenal cortical zones and adrenal medulla following low-thoracic (Th9) injury. A Representative hematoxylin and eosin-stained cross-section illustrating individual adrenal cortex zones (zona glomerulosa, zona fasciculata, and zona reticularis) and adrenal medulla. B A pronounced hypertrophy of the zona fasciculata was observed during 7 days post-injury, indicating transient cortical remodeling. Morphometric analysis was performed using the Cavalieri´s stereological method. Data are expressed as mean ± SEM. Sample sizes: intact control (n = 5); SCI: 1 dpi (n = 7); 3, 21, and 28 dpi (n = 6); 7 dpi (n = 8); 14 dpi (n = 5).**p < 0.01, ***p < 0.001 vs. intact control

• 

  Fig. 3. Quantitative analysis of circulating angiotensin II released into the bloodstream during long-term survival (1–28 days post-injury) after low-thoracic (Th9) injury. Data are expressed as mean ± SEM. Sample sizes: intact control (n = 6); SCI: 1, 14, 21, and 28 dpi (n = 6); 3 and 7 dpi (n = 5); sham-operated control: 1 and 14 dpi (n = 5); 3, 7, 21, and 28 dpi (n = 6). **p < 0.01, ***p < 0.001 vs. intact control

• 

  Fig. 4. Quantitative autoradiographic analysis of angiotensin II receptor binding in individual components of the hypothalamic–pituitary–adrenal (HPA) axis following low-thoracic (Th9) injury during long-term survival (1–28 days post-injury). A AT1 receptor expression in the paraventricular nucleus of the hypothalamus (PVN); intact control (n = 8); SCI (n = 8); sham-operated control: 1 and 3 dpi (n = 8); 7–28 dpi (n = 7). B AT1 receptor expression in the pituitary gland; intact control (n = 8); SCI and sham-operated control (n = 5). C AT1 receptor expression in the zona glomerulosa of the adrenal cortex; intact control (n = 13); SCI: 1–14 dpi (n = 8); 21 and 28 dpi (n = 7); sham-operated control: 1 and 3 dpi (n = 8); 7 and 14 dpi (n = 7); 21 and 28 dpi (n = 6). D AT2 receptor expression in the adrenal medulla; intact control (n = 15); SCI: 3, 7, 14, and 28 dpi (n = 8); 1 and 21 dpi (n = 7); sham-operated control: 1, 3, 7, and 21 dpi (n = 8); 14 and 28 dpi (n = 7). Inset representative autoradiogram demonstrates receptor localization in components of the HPA axis (scale bar = 1 mm). Quantitative data are expressed as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 vs. intact control; ###p…

• 

  Fig. 5. Post-traumatic alterations in concentrations of hormones associated with the neuroendocrine stress response and adrenal regulation after low-thoracic (Th9) injury during long-term survival (1–28 days post-injury). A Corticotropin-releasing hormone (CRH); intact control (n = 9); SCI: 1 dpi (n = 6); 3–28 dpi (n = 5); sham-operated control: 1–3 and 21–28 dpi (n = 5); 7–14 dpi (n = 6). B Adrenocorticotropic hormone (ACTH); intact control (n = 8); SCI: 7 dpi (n = 7); 1–3 and 14–21 dpi (n = 6); 28 dpi (n = 5); sham-operated control: 3 and 14–28 dpi (n = 6); 1 and 7 dpi (n = 5). C Corticosterone; intact control (n = 10); SCI (n = 5); sham-operated control (n = 5). D Aldosterone; intact control (n = 11); SCI: 1 dpi (n = 6); 3–28 dpi (n = 5); sham-operated control: 1 and 14–28 dpi (n = 6); 3–7 dpi (n = 5). E Norepinephrine; intact control (n = 7); SCI (n = 5); sham-operated control: 1 dpi (n = 5); 3–28 dpi (n = 6). F Epinephrine; intact control (n = 12); SCI (n = 5); sham-operated control: 1–7 and 21 dpi (n = 5); 14–28 dpi (n = 6). Corticosterone was quantified in adrenal tissue homogenates, whereas all other hormones were quantified in plasma. *p < 0.05, **p < 0.01, ***p < 0.001 vs.…

• 

  Fig. 6. Quantitative autoradiographic analysis of angiotensin II receptor binding in the spleen following low-thoracic (Th9) injury during long-term survival (1–28 days post-injury). A AT1 receptor binding in the splenic red pulp; intact control (n = 11); SCI: 3, 14, and 28 dpi (n = 8); 1, 7, and 21 dpi (n = 7); sham-operated control: 1 dpi (n = 5), 3–28 dpi (n = 6). Inset representative autoradiogram demonstrates receptor localization in splenic red pulp (scale bar = 1 mm). B Post-traumatic time-dependent changes in spleen weight expressed as the spleen index (normalized to body weight); intact control (n = 9); SCI: 7 dpi (n = 9); 1, 3, and 14 dpi (n = 10); 28 dpi (n = 11); 21 dpi (n = 12); sham-operated control: 1, 7, and 14 dpi (n = 9); 21 dpi (n = 8); 3 and 28 dpi (n = 7). Data are expressed as mean ± SEM and presented as a percentage of intact control. *p < 0.05, **p < 0.01, ***p < 0.001 vs. intact control; #p < 0.05, ###p < 0.001 vs. sham-operated control

• 

  Fig. 7. Quantitative autoradiographic analysis of angiotensin II receptor binding in individual components of the hypothalamic–pituitary–adrenal (HPA) axis and spleen at day 3 following high-thoracic (Th1) and low-thoracic (Th9) injury. A AT1 receptor expression in the paraventricular nucleus of the hypothalamus (PVN). B AT1 receptor expression in the pituitary gland. C AT1 receptor expression in the zona glomerulosa of the adrenal cortex. D AT2 receptor expression in the adrenal medulla. E AT1 receptor expression in the spleen. Data are expressed as mean ± SEM. Sample sizes correspond to those described in Fig. 4 (3 dpi), with the addition of the Th1 SCI group (n = 6). *p < 0.05, **p < 0.01 vs. intact control; #p < 0.05, ##p < 0.01, ###p < 0.001 vs. sham-operated control; •p < 0.05, ••p < 0.01, •••p < 0.001 vs. Th9 SCI group

• 

  Fig. 8. Hormonal changes following high-thoracic (Th1) and low-thoracic (Th9) injury. A Corticotropin-releasing hormone (CRH), B adrenocorticotropic hormone (ACTH), C corticosterone, D aldosterone, E norepinephrine, and F epinephrine. Quantitative data are expressed as mean ± SEM. Sample sizes were identical to those reported in Fig. 5, with the addition of the Th1 SCI group: CRH (n = 6), ACTH (n = 7), corticosterone (n = 7), aldosterone (n = 5), epinephrine (n = 6), and norepinephrine (n = 6). *p < 0.05, **p < 0.01, ***p < 0.001 vs. intact control; #p < 0.05, ##p < 0.01, ###p < 0.001 vs. sham-operated control; •p < 0.05, ••p < 0.01 vs. Th9 SCI group