Wang J X, Li P, Peng K M, Jin S H Z
College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, PR China.
Regul Pept. 2011 Feb 25;167(1):50-5. doi: 10.1016/j.regpep.2010.11.009. Epub 2010 Dec 3.
Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). The sequence of ghrelin has been determined in many species ranging from fish to mammals. The ostrich is the largest herbivorous bird in the world. Although the distribution, morphological characteristics, and developmental changes of ghrelin-producing cells in the gastrointestinal tract of African ostrich chicks have recently been determined, the sequence and structure of ghrelin and its expression in the gastrointestinal tract of African ostrich chicks have not been studied. In the present study, the sequence and structure of ghrelin and its expression in the gastrointestinal tract of African ostrich chicks were investigated by reverse-transcriptase polymerase chain reaction (RT-PCR). Results of cDNA cloning revealed that African ostrich ghrelin is composed of 28 amino acid residues and the sequence of the 7 amino acids of the N-terminal region of African ostrich ghrelin was identical with that of other birds. Ninety-day-old female African ostriches were used to investigate the expression of ghrelin in the gastrointestinal tract. The results showed that ghrelin mRNA existed in the proventriculus, gizzard, duodenum, ileum, cecum, and rectum; there was no expression in the jejunum and colon. We observed developmental changes in the ghrelin mRNA expression in the stomach and small intestine of African ostriches. The results of the present study showed that ghrelin mRNA existed on day 1 in the proventriculus, but there was no expression in other tissues. On day 45, ghrelin mRNA existed in the proventriculus, gizzard, and ileum; however, there was no expression in the duodenum and jejunum. On day 90 and 334, we detected ghrelin mRNA in the proventriculus, gizzard, duodenum, and ileum, but there was no expression in the jejunum. The results of the present study clearly demonstrate that ghrelin mRNA exists and the distribution of ghrelin mRNA in the gastrointestinal tract of African ostriches changes with age (from postnatal day 1 to day 334).
胃饥饿素是生长激素促分泌素受体（GHS-R）的内源性配体。胃饥饿素的序列已在从鱼类到哺乳动物的许多物种中确定。鸵鸟是世界上最大的草食性鸟类。尽管最近已确定非洲鸵鸟雏鸡胃肠道中产生胃饥饿素的细胞的分布、形态特征和发育变化，但胃饥饿素的序列和结构及其在非洲鸵鸟雏鸡胃肠道中的表达尚未得到研究。在本研究中，通过逆转录聚合酶链反应（RT-PCR）研究了非洲鸵鸟雏鸡胃饥饿素的序列和结构及其在胃肠道中的表达。cDNA克隆结果显示，非洲鸵鸟胃饥饿素由28个氨基酸残基组成，非洲鸵鸟胃饥饿素N端区域的7个氨基酸序列与其他鸟类相同。使用90日龄的雌性非洲鸵鸟来研究胃饥饿素在胃肠道中的表达。结果表明，胃饥饿素mRNA存在于腺胃、肌胃、十二指肠、回肠、盲肠和直肠中；空肠和结肠中无表达。我们观察到非洲鸵鸟胃和小肠中胃饥饿素mRNA表达的发育变化。本研究结果表明，胃饥饿素mRNA在出生第1天存在于腺胃中，但在其他组织中无表达。在第45天，胃饥饿素mRNA存在于腺胃、肌胃和回肠中；然而，十二指肠和空肠中无表达。在第90天和第334天，我们在腺胃、肌胃、十二指肠和回肠中检测到胃饥饿素mRNA，但空肠中无表达。本研究结果清楚地表明，胃饥饿素mRNA存在，并且非洲鸵鸟胃肠道中胃饥饿素mRNA的分布随年龄（从出生后第1天到第334天）而变化。
