College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, 010018, China.
Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, 010018, China.
Exp Brain Res. 2020 Apr;238(4):1085-1095. doi: 10.1007/s00221-020-05793-z. Epub 2020 Mar 25.
Ghrelin is an orexigenic agonist that acts directly on neurons in the hypothalamus, controlling appetite and energy balance. Although its role in appetite-associated neurons has been described, the relationship between peripheral ghrelin stimulation and oxytocin expression in the paraventricular nucleus is not fully understood. We evaluated the suppressive function of ghrelin in oxytocin-positive paraventricular nucleus neurons in ovariectomized C57BL/6 mice 2 h after ghrelin injection. The results showed that, in intact mice, peripheral ghrelin stimulation activated estrogen receptor alpha-expressing neurons during the estrous cycle and that agouti-related peptide mRNA expression was remarkably increased. Agouti-related peptide neuron axons co-localized with oxytocin neurons in the paraventricular nucleus. Moreover, the response of oxytocin-positive paraventricular nucleus neurons to ghrelin was suppressed in the proestrus period, while ghrelin decreased the serum concentration of estradiol in the proestrus phase. These data suggest that ghrelin may suppress oxytocin-positive neuron expression via the arcuate nucleus agouti-related peptide circuit, with the possible influence of estradiol in the murine estrous cycle. Unraveling the mechanism of ghrelin-induced oxytocin expression in the hypothalamus paraventricular nucleus broadens the horizon for ghrelin-related appetite research.
Ghrelin 是一种促食欲肽激动剂，它直接作用于下丘脑神经元，控制食欲和能量平衡。尽管已经描述了其在与食欲相关的神经元中的作用，但外周 ghrelin 刺激与室旁核催产素表达之间的关系尚未完全阐明。我们评估了 ghrelin 在卵巢切除的 C57BL/6 小鼠注射 ghrelin 后 2 小时对催产素阳性室旁核神经元的抑制作用。结果表明，在完整的小鼠中，外周 ghrelin 刺激在发情周期中激活了雌激素受体 alpha 表达神经元，并且 agouti 相关肽 mRNA 的表达显著增加。Agouti 相关肽神经元轴突与室旁核中的催产素神经元共定位。此外，ghrelin 对催产素阳性室旁核神经元的反应在发情前期受到抑制，而 ghrelin 降低了发情前期的血清雌二醇浓度。这些数据表明，ghrelin 可能通过弓状核 agouti 相关肽回路抑制催产素阳性神经元的表达，而雌激素在小鼠发情周期中可能有影响。揭示 ghrelin 诱导下丘脑室旁核催产素表达的机制，拓宽了 ghrelin 相关食欲研究的视野。
