Gastric or coeliac vagotomy decreases drinking after peripheral angiotensin II

After bilateral subdiaphragmatic vagotomy, rats drank later and less in response to peripherally administered angiotensin II [13]. We attempted to localize this deficit neurologically by performing selective gastric, hepatic or coeliac vagotomies. The drinking responses of such selectively lesioned rats to 0.1 and 1.0 mg·kg^?1 angiotensin II (SC) were compared to those of total bilateral vagotomized rats and sham vagotomized rats. Gastric or coeliac vagotomy produced drinking deficits that were similar to those produced by total abdominal vagotomy, but hepatic vagotomy did not. These results demonstrate the importance of abdominal vagal mechanisms in the drinking response to circulating angiotensin II.     

Exaggerated vasopressin secretion and attenuated osmoregulated thirst in human survivors of hyperosmolar coma

Aims/hypothesis. To test the hypothesis that subnormal thirst sensation could contribute to the development of the hypernatraemia characteristic of hyperosmolar coma, we studied osmoregulation in survivors of hyperosmolar coma. Methods. Eight survivors of hyperosmolar coma, eight control subjects with Type II (non-insulin-dependent) diabetes mellitus and eight healthy control subjects underwent water deprivation during which measurements of thirst, plasma osmolality and vasopressin were taken. Results. Water deprivation caused greater peak plasma osmolality in the hyperosmolar coma group (301.7 ± 2.7 mmol/kg) than in Type II diabetic (294.3 ± 3.2 mmol/kg, p < 0.01) or control group (296.9 ± 3.0 mmol/kg, p < 0.01) and a greater increase in plasma vasopressin concentration (hyperosmolar coma, 5.8 ± 1.3 pmol/l, Type II diabetes, 1.8 ± 1.3 pmol/l, p < 0.001, control subjects, 2.2 ± 1.8 pmol/l, p < 0.001). Thirst ratings were lower following water deprivation in the hyperosmolar coma group (3.5 ± 0.8 cm) than in Type II diabetes (7.7 ± 1.6 cm, p < 0.001) or control subjects (7.4 ± 1.3 cm, p < 0.001), and the hyperosmolar group patients drank less in 30 min following water deprivation (401 ± 105 ml) than Type II diabetic (856 ± 218 ml, p < 0.001) or control subjects (789 ± 213 ml, p < 0.001). Conclusion/interpretation. Survivors of hyperosmolar coma have subnormal osmoregulated thirst and fluid intake, which might contribute to the hypernatraemic dehydration typical of the condition. [Diabetologia (1999) 42: 534–538] Received: 22 October 1998 and in final revised form: 10 December 1998     

Inositol may reverse lithium-induced polydipsia but not polyuria

A previous open study suggested that oral inositol 3 g/day ameliorates lithium-induced polyuria–polydipsia as rated subjectively by patients. We designed a double-blind crossover study of 6 g/day oral inositol versus placebo, each given for 2 weeks, in seven patients. Inositol did not reverse lithium-induced polyuria, as measured by 24 h urine volume and urine specific gravity. However, subjects' subjective report of symptomatology was significantly improved on inositol as compared to placebo, possibly due to alleviation of polydipsia. Inositol was previously shown to reverse lithium-induced polydipsia in rats. Such a phenomenon may be mediated by either a central or a peripheral mechanism. In order to study such suggested mechanisms, we injected daily inositol or artificial CSF i.c.v. to rats exhibiting lithium-induced polydipsia. Inositol i.c.v. reversed lithium-induced polydipsia, but kidney inositol levels in Li-treated rats were not different from controls. These findings suggest that inositol may alleviate symptoms of lithium-induced polydipsia via a central effect, but has no direct effect on lithium-induced polyuria. © 1997 John Wiley & Sons, Ltd.     

从脾胃论治糖尿病浅探

糖尿病是临床中常见病和多发病,其发病率呈逐年上升趋势,已严重威胁着我国乃至世界人民的身体健康。糖尿病的发生、发展均与脾胃功能失调有关,通过大量临床观察和查阅文献,发现从脾胃论治糖尿病可收到良好的效果。为进一步阐明其致病机理,探讨治疗方法,更好地防治本病,把观点阐明如下。     

附子理中丸汤剂临床新用

附子理中丸系由《伤寒论》中的理中丸加附子而成,具有温中健脾作用.用于脾胃虚寒、脘腹冷痛,呕吐泻泄,手足不温.本着中医"异病同治"的理念,临床运用附子理中汤加减治疗心下痞、消渴、胸痹伴下肢水肿(慢性心衰)、复发性口腔溃疡伴慢性腹泻、便秘等疾病均取得满意效果,值得临床推广.此文章从上述疾病的病因病机、理法方药等方面进行分析...     

运用《金匮要略》论治糖尿病便秘探析

糖尿病在中医里归于消渴范围内,“消渴”最初是在《黄帝内经》中被提起的,到了东汉张仲景的《金匮要略》对消渴进行更为详细记载。糖尿病便秘是糖尿病患者常见的并发症,张仲景对此也有独特见解。张仲景通过辨证论治,治病求本,谨遵病因病机,通过辨证分型,归纳出不同的有效方剂,为当代中医提供了极大的参考,应当进一步挖掘其学术思想,更好的服务于临床。     

Rational regulation of water-seeking effort in rodents

In the laboratory, animals’ motivation to work tends to be positively correlated with reward magnitude. But in nature, rewards earned by work are essential to survival (e.g., working to find water), and the payoff of that work can vary on long timescales (e.g., seasonally). Under these constraints, the strategy of working less when rewards are small could be fatal. We found that instead, rats in a closed economy did more work for water rewards when the rewards were stably smaller, a phenomenon also observed in human labor supply curves. Like human consumers, rats showed elasticity of demand, consuming far more water per day when its price in effort was lower. The neural mechanisms underlying such “rational” market behaviors remain largely unexplored. We propose a dynamic utility maximization model that can account for the dependence of rat labor supply (trials/day) on the wage rate (milliliter/trial) and also predict the temporal dynamics of when rats work. Based on data from mice, we hypothesize that glutamatergic neurons in the subfornical organ in lamina terminalis continuously compute the instantaneous marginal utility of voluntary work for water reward and causally determine the amount and timing of work.

When animals have two ways to get a resource like water, they tend to choose the way that gets them more water for less work. Neural mechanisms underlying choices involving value comparisons are well studied (1). The reward literature has focused on how the relative subjective value or “utility” of each option is determined by weighing benefits (such as reward magnitude or quality) against costs (such as delay, risk, or effort). The identified neural mechanisms for utility computation mostly involve striatal and limbic reward circuits and dopamine.Much less is known about how animals assess the absolute value of a single, available option to decide whether or not to attempt to harvest a potential reward. In one of the few such studies, when mice were offered only one way to get water at a time, they worked harder during the time blocks when the water reward was larger (2). This makes sense—save energy for when the work will pay off most—but it can’t be the whole story. If motivation were driven entirely by expected reward, animals would be less motivated to work for water during a drought (because they would expect less reward per unit of effort) and might die of thirst. This problem is partly offset by the fact that the perceived value of a reward is normalized according to recent experience, such that rewards that would have been considered small in a rich environment are perceived as large relative to a lean environment (3–5). But normalization would at best equalize motivation between rich and lean environments. If the difficulty of getting water changes slowly compared to the timescale of physiological necessity, animals must invest the most effort to gain it precisely when the reward for that effort is least.To explore how animals adapt to this kind of challenge, we maintained rats in a live-in environment where all their water was earned by performing a difficult sensory task. We varied the reward magnitude and measured rats’ effort output and water consumption. As expected, rats did more trials per day when the reward per trial was smaller, thus maintaining healthy hydration levels regardless of reward size. More surprisingly, however, rats worked for more water per day (and far more than they needed) when it was easier to earn. This suggests that they can regulate their consumption dramatically (up to threefold) to conserve effort when times are lean or cash in during times of abundance. In economic terms, rats show a strong elasticity of demand for water, even though essential commodities without substitutes are expected to be inelastic.Classic animal behavior studies noted both these effects in experiments designed to validate economic utility maximization theory (6–8). Here, we revisit and extend that theoretical framework with the goal of relating utility maximization to behavioral dynamics and candidate neural mechanisms. This study differs from the recent literature on utility maximization in choice behavior in two ways. Behaviorally, we focus here on the choice between action and inaction under a closed economy with closed-loop feedback on value (in which state changes as a function of past choices). Mechanistically, we implicate lamina terminalis, a forebrain circuit which has not been previously linked to utility computations.     

Awareness of Fluid Losses Does Not Impact Thirst during Exercise in the Heat: A Double-Blind,Cross-Over Study

Background: Thirst has been used as an indicator of dehydration; however, as a perception, we hypothesized that it could be affected by received information related to fluid losses. The purpose of this study was to identify whether awareness of water loss can impact thirst perception during exercise in the heat. Methods: Eleven males participated in two sessions in random order, receiving true or false information about their fluid losses every 30 min. Thirst perception (TP), actual dehydration, stomach fullness, and heat perception were measured every 30 min during intermittent exercise until dehydrated by ~4% body mass (BM). Post exercise, they ingested water ad libitum for 30 min. Results: Pre-exercise BM, TP, and hydration status were not different between sessions (p > 0.05). As dehydration progressed during exercise, TP increased significantly (p = 0.001), but it was the same for both sessions (p = 0.447). Post-exercise water ingestion was almost identical (p = 0.949) in the two sessions. Conclusion: In this study, thirst was a good indicator of fluid needs during exercise in the heat when no fluid was ingested, regardless of receiving true or false water loss information.     

Vasopressin: physiology,assessment and osmosensation

Vasopressin (AVP) plays a major role in the regulation of water and sodium homeostasis by its antidiuretic action on the kidney, mediated by V2 receptors. AVP secretion is stimulated by a rise in plasma osmolality, a decline in blood volume or stress. V1a receptors are expressed in vascular smooth muscle cells, but the role of vasopressin in blood pressure regulation is still a matter of debate. AVP may also play a role in some metabolic pathways, including gluconeogenesis, through its action on V1a receptors expressed in the liver. It is now understood that thirst and arginine vasopressin (AVP) release are regulated not only by the classical homeostatic, intero‐sensory plasma osmolality negative feedback, but also by novel, extero‐sensory, anticipatory signals. AVP measurement is time‐consuming, and AVP level in the blood in the physiological range is often below the detection limit of the assays. Recently, an immunoassay has been developed for the measurement of copeptin, a fragment of the pre‐provasopressin molecule that is easier to measure. It has been shown to be a good surrogate marker of AVP.     

亓鲁光教授同病异治糖尿病经验

亓鲁光教授认为,古时消渴三消辨证,目前已很难满足现代临床诊治糖尿病的需要,临床辨证应大胆地突破三消辨证,应辨证辨病相结合,同病异治,异证求同,中西医结合,尤重固本化瘀疏肝之法,综合改善胰岛功能,平稳降低血糖。