The nucleus tractus solitarii (NTS), located in the brainstem, is one of the main nuclei responsible for integrating different signals in order to originate a specific and orchestrated autonomic response. Antihypertensive drugs are well known to stimulate alpha 2-adrenoceptor (alpha 2R) in brainstem cardiovascular regions to induce reduction in blood pressure. Because alpha 2R impairment is present in several models of hypertension, the aim of the present study was to investigate the distribution and density of alpha 2R binding within the NTS of Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats during development (1,15,30 and 90day-old) by an in vitro autoradiographical study. The NTS shows heterogeneous distribution of alpha 2R in dorsomedial/dorsolateral, subpostremal and medial/intermediate subnuclei. Alpha 2R increased from rostral to caudal dorsomedial/dorsolateral subnuclei in 30 and 90day-old SHR but not in WKY. Alpha 2R decreased from rostral to caudal subpostremal subnucleus in 15, 30 and 90day-old SHR but not in WKY. Medial/intermediate subnuclei did not show any changes in alpha 2R according to NTS levels. Furthermore, alpha 2R are decreased in SHR as compared with WKY in all NTS subnuclei and in different ages. Surprisingly, alpha 2R impairment was also found in pre-hypertensive stages, specifically in subpostremal subnucleus of 15day-old rats. Finally, alpha 2R decrease from 1 to 90day-old rats in all subnuclei analyzed. This decrease is different between strains in rostral dorsomedial/dorsolateral and caudal subpostremal subnuclei within the NTS. In summary, our results highlight the importance of alpha 2R distribution within the NTS regarding the neural control of blood pressure and the development of hypertension. © 2011 Elsevier B.V.
Carrettiero, D. C., Ferrari, M. F. R., & Fior-Chadi, D. R. (2012). Alpha 2-adrenergic receptor distribution and density within the nucleus tractus solitarii of normotensive and hypertensive rats during development. Autonomic Neuroscience: Basic and Clinical, 166(1–2), 39–46. https://doi.org/10.1016/j.autneu.2011.10.004