Diamine oxidase in relation to diamine and polyamine metabolism

Diamine oxidase catalyzes the oxidative deamination of short chain aliphatic diamines, like putrescine, and histamine. The enzyme is rate-limiting in the terminal catabolism of polyamines, which are endogenous polycations important for cell growth and differentiation. This review examines the behavior of diamine oxidase in mammalian tissues in relation to diamine and polyamine metabolism under physiological and pathological conditions. The role of diamine oxidase in the control of putrescine levels in growing tissues and the known mechanisms responsible for the enzyme expression are also described.     

Receptors involved in the nervous system regulation of polyamine metabolism in rat salivary glands

Polyamines are important for protein synthesis and tissue growth. In rat salivary glands, the activity of ornithine decarboxylase (ODC), the enzyme catalysing the formation of putrescine, and the content of putrescine, spermidine, spermine and N1-acetylspermidine were assayed after parasympathetic or sympathetic nerve stimulation in the presence of various autonomic receptor blockers. Increases in ODC activity occurred on activation of non-adrenergic and non-cholinergic receptors in response to parasympathetic nerve stimulation and on activation of alpha(alpha 1)- as well as of beta(beta 1)-adrenoceptors in response to sympathetic nerve stimulation. Moreover, in parotid glands, a beta(beta 1)-adrenoceptor-mediated inverse pathway for putrescine formation seemed to exist: from spermidine via N1-acetylspermidine.     

Substance P and vasoactive intestinal peptide influence polyamine metabolism in salivary glands of the rat

In parotid, sublingual and submaxillary glands stimulated by continuous intravenous infusion of the neuropeptides substance P or vasoactive intestinal peptide at various doses for 3 h, the concentrations of the polyamines putrescine, spermidine, spermine and N1-acetylspermidine as well as the activity of ornithine decarboxylase were determined. This enzyme catalyses the synthesis of putrescine and is the key enzyme in polyamine formation. Vasoactive intestinal peptide induced the most marked effects, and the most conspicuous findings were made in the sublingual glands, where the ornithine decarboxylase activity was found to have increased more than 100-fold, accompanied by an increased level of putrescine in those glands which were removed immediately after the end of the infusion. When, instead, the glands were removed 5 h after the end of the infusion there was no longer any increase in the activity of ornithine decarboxylase or in putrescine concentration, but now spermidine and spermine were found to be increased. Interestingly, the parasympathetic non-adrenergic, non-cholinergic regulation of polyamine metabolism in the major salivary glands of the rat is most predominant in the sublingual glands.     

Developmental changes of sugar occurrence and distribution in the rat submandibular and sublingual glands

 The developmental expression of salivary glycoconjugates was investigated in the rat submandibular and sublingual glands by conventional and lectin histochemistry. By the time of the first differentiation of secretory structures, in spite of similar morphological features, a different histochemical reactivity was detected, accounting for a relevant content of neutral glycoconjugates in the submandibular gland and the occurrence of both neutral and acidic glycoconjugates in the sublingual one. The use of lectins allowed the main changes of secretory components to be noted around gestational day 18. DBA and WGA lectins seemed to act as pre- and post-natal development markers while Con A lectin was indicative of post-natal differentiation. Taken together, data from lectin histochemistry indicated the transitional occurrence of glycoconjugates, probably involved in temporally restricted functions, as well as the co-existence of different secretory components that might also reflect maturational changes of single products. Accepted: 31 July 1998     

The fine structural localization of acetylcholinesterase activity in the rat parotid and sublingual glands

The fine structural localization of acetylcholinesterase activity was studied in the rat parotid and sublingual glands. In both glands, reaction product was found in association with the axolemmae of stromal axons invested by Schwann cells and between the contact with effector cells. In the sublingual gland, reaction product was also found in association with surface vesicles and pits and the rough endoplasmic reticulum of myoepithelial cells.     

A comparison of the effects of bilateral sections of the chorda tympani nerve and extirpation of the submaxillary and sublingual salivary glands on the eating and drinking patterns of the rat

The chorda tympani nerve (CT) innervates the fungiform papillae on the tip of the tongue and has been considered an important nerve for the sense of taste. The CT also contains the parasympathetic supply to the submaxillary and sublingual salivary glands. Therefore, changes in taste or feeding behavior following bilateral sections of CT are caused by both degeneration of fungiform papillae and the inevitable partial desalivation of the rat. In the present experiments we compared the effects of bilateral chorda tympani nerve sections with extirpation of submaxillary and sublingual glands on daily home cage eating and drinking patterns in the rat. Before and after surgery we analyzed the daily eating and drinking patterns, including such measures as intake, bout number, bout length, interbout interval and rate of consumption during bouts. The results of desalivation and bilateral CT sections were indistinguishable. The most profound change was that eating bout duration was increased following surgery. Since food intake did not increase, the results indicate a marked loss in eating efficiency over the daily ingestion periods. Although the eating patterns of desalivated and chorda tympani sectioned rats are quite similar, the evidence is not compelling that they have the same physiological basis. A second experiment was designed to test the hypothesis that the atypical eating patterns observed following bilateral sectioning of CT were the direct result of partial desalivation resulting from the denervation of the salivary glands. In this experiment a unilateral section was made of one CT and it was shown that the eating behavior was not affected. Then the contralateral submaxillary and sublingual salivary glands were removed. This resulted in a six-fold increase in feeding bout length. In all cases a unilateral CT section combined with extirpation of the contralateral salivary glands resulted in rats whose eating behavior was indistinguishable from the earlier data following either the bilateral CT sections or bilateral desalivations. The conclusion is drawn that the eating irregularities noted following bilateral CT sections result from this partial desalivation. CT sections were verified by taste bud counts in the fungiform papillae and histological examinations were made of salivary glands in rats receiving CT sections.     

The effect of reserpine treatment on choline acetyltransferase activity in rat submaxillary glands

Rats were treated daily with a low dose of reserpine (0.1 mg kg-1) injected subcutaneously for 3 weeks. In the submaxillary glands the noradrenaline content was reduced by about 95%. The total activity of the acetylcholine-synthesizing enzyme choline acetyltransferase remained unchanged. However, the activity of this enzyme was found to be increased when the reserpine treatment was followed by surgical sympathetic denervation and the glands were analysed 3 weeks post-operatively. The enzyme activity also increased in the glands when the surgical sympathetic denervation was performed on the day of the start of the reserpine treatment. The lack of effect of reserpine on choline acetyltransferase activity in the glands seems to exclude the possibility that it is the depletion of neuronal noradrenaline stores that initiates the events giving rise to increases in choline acetyltransferase activity after sympathetic denervation.     

The action of physalaemin on electrolyte excretion by the mandibular and sublingual salivary glands of the rat

The effect of physalaemin, an undecapeptide belonging to a family known collectively as the tachykinins, on water and electrolyte excretion of the mandibular and sublingual salivary glands of the rat has been investigated and compared to that of acetylcholine. Drugs were administered intravenously or by close-arterial infusion. Physalaemin is a powerful stimulant of fluid secretion by both glands although less potent than acetylcholine. The Na and K excretion patterns in physalaemin-evoked saliva resembled, but were by no means identical to those evoked by acetylcholine and other parasympathomimetic drugs: saliva evoked by physalaemin was considerably poorer in Na and K at all secretory rates. The HCO₃ excretion curves, on the other hand, seemed to be identical to those evoked by parasympathomimetic drugs. From an analysis of the Na and K excretion patterns, it can be concluded, both for the mandibular and the sublingual glands, that physalaemin stimulates Na reabsorption and K secretion across the gland duct epithelium, whereas acetylcholine has the opposite effect. These findings agree nicely with what has previously been demonstrated in vitro in the isolated perfused main excretory duct of the rat mandibular gland.     

In vitro metabolism of putrescine by diamine oxidase in tissues of the pregnant rat

The metabolism of¹⁴C-putrescine by diamine oxidase was tested on the 19th day of pregnancy in different organs of rats. The highest turnover was found in maternal placenta and uterus where 94% of the reaction product was identified as ¹-pyrroline. Considerable deamination rates were also observed in ovary, liver and fetal placenta where, however, -aminobutyric acid was the predominant product. In the kidney only a small diamine oxidase activity was measured. No formation of spermidine or spermine from¹⁴C-putrescine was detected.     

三叶因子2在大鼠下颌下腺内的表达及其与实验性胃溃疡愈合的关系

目的 探讨大鼠实验性胃溃疡自愈期间三叶因子2(TFF2)在大鼠下颌下腺的表达及其与胃溃疡愈合的关系. 方法 48只雄性SD大鼠分为溃疡组和正常组,采用免疫组织化学和RT-PCR法,检测溃疡组和正常组大鼠下颌下腺中TFF2肽和基因的表达情况. 结果 TFF2免疫反应阳性物质主要位于纹状管、闰管和小叶间导管、颗粒曲管少颗粒细胞的胞质,管腔内亦有阳性物质表达,近腔面处较多.和正常组相比,溃疡1d时TFF2阳性物质面密度和积分吸光度明显增高,2d时最低,4、6d时逐渐升高(P<0.01),10～23d时均维持在较高水平(P<0.05).溃疡1、2、4、6、10、14、23d TFF2/GAPDH吸光度比值除2d溃疡组略有增高外,其他各溃疡组明显高于正常对照组(P<0.01或P<0.05). 结论 大鼠下颌下腺中TFF2参与了胃溃疡愈合过程的调节.