Involvement of median preoptic nucleus and medullary noradrenergic neurons in cardiovascular and sympathetic responses of hemorrhagic rats

Figure 1. (A) Representative photomicrograph of coronal section of the hypothalamus (40 μm) showing a typical site of nanoinjection in the median preoptic nucleus (MnPO). The arrow indicates the marking of the MnPO with evans blue dye 4%. AC: anterior commissure. The scale bar is equal to 500 µm. (B) Effects of MnPO pharmacological inhibition on changes in Mean arterial pressure (MAP), (C) heart rate (HR) and (D) integral of renal sympathetic nervous activity (∫RSNA) variations in the rats submitted to hypovolemic hemorrhagic in the MnPO Sham (MnPOS; n = 6) and MnPO Inhibition (MnPOI; n = 6) groups. Values were expressed as means ± standard error of the mean (S.E.M). *Different from time 0; †different from sham group with p < 0.05. The black bar represents the hemorrhage period. The dashed line represents the HSS infusion (3M; NaCl). The arrow indicates nanoinjection in the MnPO.

Figure 2. (A) Representative photomicrograph of coronal medulla section (40 μm) marked by immunohistochemistry. The arrows indicate the marking of TH positive neurons in the nucleus of the solitary tract (NTS - cluster A2), in caudal ventrolateral medulla (CVLM - cluster A1) and rostrovetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A2S) or saporin-anti-DβH (A2L) in NTS. The scale bar is equal to 100 µm. (B) Quantification of the number of TH positive cells in the medullary regions. Mean ± standard error of the mean (S.E.M.) of the number of positive TH cells located in the nucleus of the solitary tract (NTS – clusters A2 and C2), the caudal ventrolateral medulla (CVLM – cluster A1) and rostral vetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A2S) or saporin-anti-DβH (A2L) in NTS. †Different from sham group with p < 0.05. (C) Effects of A2 catecholaminergic neuron lesions on changes in Mean arterial pressure (MAP), (D) heart rate (HR) and (E) integral of renal sympathetic nervous activity (∫RSNA) variations in the rats submitted to hypovolemic hemorrhagic in the A2 Sham…

Figure 3. (A) Representative photomicrograph of coronal medulla section (40 μm) marked by immunohistochemistry. The arrows indicate the marking of TH positive neurons in the nucleus of the solitary tract (NTS - cluster A2), in caudal ventrolateral medulla (CVLM - cluster A1) and rostrovetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A1S) or saporin-anti-DβH (A1L) in CVLM. The scale bar is equal to 100 µm. (B) Quantification of the number of TH positive cells in the medullary regions. Mean ± standard error of the mean (S.E.M.) of the number of positive TH cells located in the nucleus of the solitary tract (NTS – clusters A2 and C2), the caudal ventrolateral medulla (CVLM – cluster A1) and rostral vetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A1S) or saporin-anti-DβH (A1L) in CVLM. †different from sham group with p < 0.05. (C) Effects of A1 + A2 catecholaminergic neuron lesions on changes in Mean arterial pressure (MAP), (D) heart rate (HR) and (E) integral of renal sympathetic nervous activity (∫RSNA) variations in the rats submitted to hypovolemic hemorrhagic in the A1…

Figure 4. (A) Representative photomicrograph of coronal medulla section (40μm) marked by immunohistochemistry. The arrows indicate the marking of TH positive neurons in the nucleus of the solitary tract (NTS - cluster A2), in caudal ventrolateral medulla (CVLM - cluster A1) and rostral vetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A1 + A2S) or saporin-anti-DβH (A1 + A2L) in CVLM and NTS. The scale bar is equal to 100 µm. (B) Quantification of the number of TH positive cells in the medullary regions. Mean ± standard error of the mean (S.E.M.) of the number of positive TH cells located in the nucleus of the solitary tract (NTS – clusters A2 and C2), the caudal ventrolateral medulla (CVLM – cluster A1) and rostral vetrolateral medulla region (RVLM - cluster C1) of the animals receiving nanoinjection of bilateral saporin (A1 + A2S) or saporin-anti-DβH (A1 + A2L) in CVLM and NTS. †Different from sham group with p < 0.05. (C) Effects of A1 + A2 catecholaminergic neuron lesions on changes in Mean arterial pressure (MAP), (D) heart rate (HR) and (E) integral of renal sympathetic nervous activity (∫RSNA) variations in the rats submitted…

Figure 5. (A) Effects of A1 + A2 catecholaminergic neuron lesions and MnPO inhibition on changes in mean arterial pressure (Δ% MAP), (B) heart rate (Δ% HR) and (C) integral of renal sympathetic nervous activity (Δ% ∫RSNA) variations in the rats submitted to hypovolemic hemorrhagic in the A1 + A2 lesioned (A1 + A2L; n = 6) and MnPO inhibition (MnPOI; n = 6) groups. Values were expressed as means ± standard error of the mean (S.E.M.). *Different from time 0; †different from A1 + A2L group with p < 0.05. The black bar represents the hemorrhage period. The dashed line represents HSS infusion (3M; NaCl).

Figure 6. Post-systolic spectrum of (A,B) arterial pressure (AP), (C,D) renal sympathetic nerve activity (SNA) and coherence values between AP and RSNA power spectrum (E,F) in the rats submitted to hypovolemic hemorrhagic in the MnPO Sham (MnPOS; n = 6) and MnPO Inhibition (MnPOI n = 6) groups.

Figure 7. Post-systolic spectrum of (A,B) arterial pressure (AP), (C,D) renal sympathetic nerve activity (SNA) and coherence values between AP and RSNA power spectrum (E,F) in the rats submitted to hypovolemic hemorrhagic in the A1 + A2 Sham (A1 + A2S; n = 6) and A1 + A2 lesioned (A1 + A2L n = 6) groups.

Figure 8. Central pathways involved in the resuscitation of hypertensive hemorrhage promoted by sodium overload. Caudal ventrolateral medulla (CVLM), nucleus of the solitary tract (NTS), magnocellular hypothalamic paraventricular nucleus (mPVN), parvocellular hypothalamic paraventricular nucleus (pPVN), median preoptic nucleus (MnPO), subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), rostrovetrolateral medulla region (RVLM), oxytocin (OT), vasopressin (VP).