Mircić G M, Beleslin D B, Janković S M
Institute of Pharmacology and Toxicology, School of Medicine, Kragujevac.
Srp Arh Celok Lek. 1998 Mar-Apr;126(3-4):111-8.
Arginine vasopressin is the main hormone involved in the regulation of body fluid osmolality. The hormone is released by the posterior pituitary whenever water deprivation causes an increased plasma osmolality or whenever the cardiovascular system is challenged by hypovolaemia and/or hypotension. The main site of action of this hormone is the renal collecting duct, but vasopressin is also a potent vasopressor and neurotransmitter, it has a role in the secretion of corticotrophin, in the regulation of the cardiovascular system, temperature and other visceral functions. Vasopressin also promotes the release of coagulation factors by vascular endothelium and increases platelet aggregability. In addition to its classical contractile effect on uterine myometrial and mammary glandular myoepithelial cells, oxytocin acts as neurotransmitter, stimulates endometrial prostaglandin production, pituitary prolactin secretion, luteolysis, sperm transport and natriuresis, and may play a role in immune function. Sensorial stimuli arising from the cervix and vagina as well as stimulation of the breast can induce secretion of oxytocin from the posterior pituitary. There are many vasopressin and oxytocin analogues (agonists and antagonists) that are synthetized with the goal of increasing duration of action and selectivity for the receptor subtypes, while non-peptide antagonists are orally active. The oxytocin and the vasopressin V1a, V1b and V2 receptors have recently been cloned and shown to form a sub-family within the large superfamily of G-protein-linked receptors. Renal V2 receptors mediate vasopressin-induced water reabsorption via induction of intracellular cAMP production in collecting duct cells. Most remaining actions of vasopressin on blood vessel constriction, liver glycogenolysis, platelet adhesion, adrenal angiotensin II secretion and certain brain functions are mediated via V1a-type receptors that are coupled to a Gq/11 protein. V1 receptor activation leads to stimulation of phospholipases C, D and A2, and an increase in intracellular calcium. Vasopressin stimulates pituitary corticotrophin release via a third vasopressin receptor type (V1b) which is present in corticotrophs. Oxytocin induces myometrial contraction, endometrial prostaglandin F2a production, mammary gland milk ejection, renal natriuresis and specific sexual, affilitative and maternal behaviours via oxytocin receptors which are also coupled to a G1/11 protein. Although only one oxytocin receptor type has been cloned so far, recent binding studies indicate that uterine endometrial oxytocin receptors may constitute a distinct receptor subtype. Expression of oxytocin receptors have relevant up- and down-regulation by oestrogens and progesterone.
精氨酸加压素是参与调节体液渗透压的主要激素。每当缺水导致血浆渗透压升高，或者心血管系统受到低血容量和/或低血压挑战时，后叶垂体就会释放这种激素。这种激素的主要作用部位是肾集合管，但加压素也是一种强效血管加压剂和神经递质，它在促肾上腺皮质激素的分泌、心血管系统调节、体温调节及其他内脏功能方面发挥作用。加压素还能促进血管内皮释放凝血因子并增加血小板聚集性。除了对子宫肌层和乳腺腺泡肌上皮细胞具有经典的收缩作用外，催产素还作为神经递质发挥作用，刺激子宫内膜前列腺素生成、垂体催乳素分泌、黄体溶解、精子运输和利钠作用，并且可能在免疫功能中发挥作用。来自子宫颈和阴道的感觉刺激以及对乳房的刺激可诱导后叶垂体分泌催产素。有许多加压素和催产素类似物（激动剂和拮抗剂）被合成出来，目的是延长作用持续时间并提高对受体亚型的选择性，同时非肽类拮抗剂具有口服活性。催产素以及加压素V1a、V1b和V2受体最近已被克隆，并显示在G蛋白偶联受体的大型超家族中形成一个亚家族。肾脏V2受体通过诱导集合管细胞内cAMP生成来介导加压素诱导的水重吸收。加压素对血管收缩、肝糖原分解、血小板黏附、肾上腺血管紧张素II分泌及某些脑功能的大多数其余作用是通过与Gq/11蛋白偶联的V1a型受体介导的。V1受体激活会刺激磷脂酶C、D和A2，并增加细胞内钙含量。加压素通过存在于促肾上腺皮质激素细胞中的第三种加压素受体类型（V1b）刺激垂体促肾上腺皮质激素释放。催产素通过同样与G1/11蛋白偶联的催产素受体诱导子宫肌层收缩、子宫内膜前列腺素F2a生成、乳腺射乳、肾脏利钠作用以及特定的性行为、亲和行为和母性行为。尽管到目前为止仅克隆出一种催产素受体类型，但最近的结合研究表明，子宫内膜催产素受体可能构成一种独特的受体亚型。雌激素和孕激素对催产素受体的表达有相关的上调和下调作用。
