Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), 05508-000 São Paulo/SP, Brazil.
Edison Biotechnology Institute and Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA.
Brain Res. 2022 Sep 15;1791:147995. doi: 10.1016/j.brainres.2022.147995. Epub 2022 Jun 30.
Growth hormone (GH)-responsive neurons regulate several homeostatic behaviors including metabolism, energy balance, arousal, and stress response. Therefore, it is possible that GH-responsive neurons play a role in other responses such as CO/H-dependent breathing behaviors. Here, we investigated whether central GH receptor (GHR) modulates respiratory activity in conscious unrestrained mice. First, we detected clusters of GH-responsive neurons in the tyrosine hydroxylase-expressing cells in the rostroventrolateral medulla (C1 region) and within the locus coeruleus (LC). No significant expression was detected in phox2b-expressing cells in the retrotrapezoid nucleus. Whole body plethysmography revealed a reduction in the tachypneic response to hypoxia (FiO = 0.08) without changing baseline breathing and the hypercapnic ventilatory response. Contrary to the physiological findings, we did not find significant differences in the number of fos-activated cells in the nucleus of the solitary tract (NTS), C1, LC and paraventricular nucleus of the hypothalamus (PVH). Our finding suggests a possible secondary role of central GH action in the tachypneic response to hypoxia in conscious mice.
生长激素（GH）反应神经元调节多种稳态行为，包括代谢、能量平衡、觉醒和应激反应。因此，GH 反应神经元可能在其他反应中发挥作用，如 CO/H 依赖性呼吸行为。在这里，我们研究了中枢 GH 受体（GHR）是否调节清醒、不受约束的小鼠的呼吸活动。首先，我们在表达酪氨酸羟化酶的细胞中检测到 GH 反应神经元簇在延髓腹外侧（C1 区）和蓝斑内（LC）。在位于梯形核中的 phox2b 表达细胞中未检测到明显的表达。全身呼吸描记法显示，低氧（FiO=0.08）时的呼吸急促反应减少，而基线呼吸和高碳酸血症性通气反应没有改变。与生理发现相反，我们没有发现孤束核（NTS）、C1、LC 和下丘脑室旁核（PVH）中 fos 激活细胞的数量有显著差异。我们的发现表明，中枢 GH 作用在清醒小鼠低氧性呼吸急促反应中可能发挥次要作用。
