Expression and distribution of novel peptidehormones in memory and learning system of cephalopod brain

从章鱼脑中克隆了一个与促性腺激素释放肽（GnRH）同源的孤儿受体。在非洲爪蟾卵母细胞中表达的受体可通过应用oct-GnRH引起Cl^-电流，而脊椎动物GnRH不能触发该电流。利用该检测系统，对章鱼脑提取物进行了HPLC分级，并对纯化后的产物进行了鉴定。因此，克隆的受体被去孤儿化为oct-GnRH受体（oct-GnRHR）。Oct-GnRHR mRNA在中枢和外周神经系统、颊肌、唾液腺、生殖器、直肠、主动脉、心脏、卵巢、睾丸等组织中广泛表达。这些结果表明，oct-GnRH是一种多功能肽，除了作为一种激素在外周发挥作用外，还在神经传递和神经调节中发挥重要的中枢作用。Oct-GnRH免疫反应阳性神经元和纤维分布于食管下前块（手臂运动），后食管下肿块（内脏运动和虹吸运动）、视束叶和基底叶（姿势控制）、嗅叶、上级颊叶（味觉和触觉的较高中心），下额叶（较高的触觉中心）、上级额叶（较高的视觉中心）和垂直叶（较高的视觉和触觉中心）。这些高级中心被认为与海马和大脑皮层同源。章鱼加压素，催产素/加压素超家族中的章鱼肽，在垂直叶中也具有免疫反应性。可以认为这些肽具有重要的作用，包括进食、记忆、学习、运动和自主功能。

An orphan receptor homologous to gonadotropin-releasing peptide (GnRH) was cloned from the brain of octopus (Octopus vulgaris). The receptor expressed in Xenopus oocyte caused Cl^--current by application of oct-GnRH, however, vertebrate GnRHs failed to trigger the current. Using this assay system, the octopus brain extract was fractionated by HPLC, then, the purified material was identified to oct-GnRH. Thus, the cloned receptor was deorphaned to be the oct-GnRH receptor (oct-GnRHR). Oct-GnRHR mRNA was widely expressed in the central and peripheral nervous system, the tissues such as buccal muscle, salivary gland, crop, rectum, aorta, heart, ovary, testis, etc. Oct-GnRH caused contractions of buccal muscle and exhibited the synthesis and release of sex steroids from the ovary and testis. These results suggested that oct-GnRH is a multifunctional peptide with important central roles in neurotransmission and neuromodulation in addition to the peripheral role as a hormone.The distribution of oct-GnRH in the brain was further studied. Oct-GnRH-immunoreactive neurons and fibers were distributed in the anterior subesophageal mass (movement of arms), posterior subesophageal mass (visceral movement and siphon movement), optic tract lobe and basal lobe (posture control), olfactory lobe, superior buccal lobe (higher center of taste and touch), inferior frontal lobe (higher center of touch), superior frontal lobe (higher center of vision), and vertical lobe (higher center of vision and touch). These higher centers are believed to be homologous to hippocampus and cerebral cortex. Octopressin, an octopus peptide in the oxytocin/vasopressin-superfamily, was also immunoreactive in the vertical lobe. It can be proposed that these peptides have important roles, including feeding, memory, learning, movement, and autonomic functions.