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Vasomotor projections from the anteroventral third ventricle (AV3V) region
Insights
The anteroventral third ventricle (AV3V) region influences blood pressure regulation. Neuronal projections from the AV3V to the mesencephalon, specifically the central gray, are crucial for these cardiovascular effects, impacting hypertension models.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Hypertension Research
Background:
- The anteroventral third ventricle (AV3V) region is implicated in experimental hypertension.
- Descending projections from the AV3V to the mesencephalon are known.
- The specific cardiovascular regulatory pathways are not fully understood.
Purpose of the Study:
- To functionally identify projections from the AV3V region to the mesencephalon involved in cardiovascular regulation.
- To investigate the role of the mesencephalic central gray in mediating AV3V-induced hemodynamic responses.
Main Methods:
- Electrical stimulation of the AV3V region and rostral central gray.
- Comparison of regional hemodynamic responses (vasodilation/vasoconstriction) before and after mesencephalic tissue ablation.
- Assessment of adrenal catecholamine dependence via adrenalectomy.
Main Results:
- AV3V stimulation caused hindquarter vasodilation, renal/mesenteric vasoconstriction, depressor response, and bradycardia.
- These responses were partially dependent on adrenal catecholamines.
- Ablation of mesencephalic central gray significantly reduced AV3V-induced hindquarter, mesenteric, and depressor responses.
Conclusions:
- Neuronal projections from the rostral medial hypothalamus through the mesencephalic central gray are critical for cardiovascular control.
- This pathway is important for the development of certain hypertension models.
- The findings highlight a key neural circuit in blood pressure regulation.
Abstract:
The anteroventral third ventricle (AV3V) region is necessary for the development of a variety of models of experimental hypertension. Neuroanatomic studies have identified descending projections from this region to the mesencephalic central gray and tegmentum. This study was done to identify functionally the projections involved in cardiovascular regulation from the AV3V region to the mesencephalon. Regional hemodynamic responses to electrical stimulation of the AV3V region were compared with responses to stimulation of the rostral central gray, and these responses were compared before and after ablation of mesencephalic tissue. Stimulation of the AV3V region elicited hindquarter, vasodilation and renal and mesenteric vasoconstriction associated with a depressor response and bradycardia. These responses were partially dependent on adrenal catecholamines since adrenalectomy reduced hindquarter, mesenteric, and depressor responses. Regional hemodynamic responses to central gray stimulation were qualitatively similar and also demonstrated a partial dependence on adrenal catecholamines. After electrolyte ablation of central gray tissue, significant reductions in hindquarter, mesenteric, and depressor responses to AV3V stimulation were observed. These observations suggest that a cardiovascular control system important for the development of several models of hypertension may be dependent on neuronal projections from the rostral medial hypothalamus through the mesencephalic central gray.