Effects of epinephrine treatment on the rat parathyroid gland, with special reference to the frequency of storage granules

Effects of epinephrine treatment on the rat parathyroid gland were studied morphologically. The mean number of storage granules per cell section (NSG) was rapidly decreased as early as 5 min after an injection of epinephrine and seemed to reach a minimum between 5 and 30 min. During this period, serum calcium levels (SCL) gradually rose and reached a maximum at 30 min. The ultrastructure of chief cells in these epinephrine-injected rats showed no marked difference as compared with that in control rats. In slightly hypocalcemic rats, induced previously by 2% EDTA-treatment, NSG was more rapidly decreased. It was suggested that storage granules may be released promptly by epinephrine treatments in spite of high SCL and that they are more promptly released under hypocalcemia.     

Effects of short-term treatment with calcium on the parathyroid gland of the rat,under particular consideration of the alteration of storage granules

Summary Short-term effects of CaCl₂-treatment on parathyroid cells of the rat, especially on their storage granules, were studied at the ultrastructural level. After an injection of 4% CaCl₂, serum calcium levels (SCL) rapidly increased from 9.1 mg/dl (controls) to a maximum of 14.9 mg/dl at 20 min. At 5 min after the injection, the number of type-I storage granules (large core) [NSG-I] and that of type-II storage granules (small core) [NSG-II] remained unchanged, in spite of elevated SCL (12.4 mg/dl). As soon as SCL rose to 13.2 mg/dl at 7.5 min, NSG-I gradually decreased to a minimum at 30 min; in contrast, NSG-II gradually increased to a maximum at 30 min. Vacuolar bodies also increased together with the augmentation of type-II storage granules. The average diameter of the core of the storage granules decreased significantly after the injection. Protein A-gold method for immunocytochemistry showed that the cores of these granules contain parathormone. Acid-phosphatase activity was occasionally found in storage granules of both types, especially in those of type II. It is concluded (i) that type-I storage granules may be transformed into vacuolar bodies via type-II granules as a result of hydrolysis, and (ii) that these processes may be accelerated during hypercalcemia.     

Freeze-fracture study of the rat parathyroid gland under hypo- and hypercalcemic conditions,with special reference to secretory granules

Summary Freeze-fracture images of the parenchymal cells in the parathyroid gland of rats were observed after vitamin D₂ plus calcium chloride-suppression and EGTA-activation of secretion. In cells of the suppressed glands, large bulges protruded from the Golgi cisternae, and large granules with a stalk, which are identified as storage granules, suggest that, during maturation, some storage granules may be connected by long tubules with the Golgi cisternae and supplied with secretory products from the Golgi cisternae via these tubules.In the activated glands, presumptive exocytotic and endocytotic specializations of intramembranous particles of the parenchymal cell plasma membrane were frequently observed. In addition, elevations and complementary shallow depressions of various shape and extent were occasionally encountered in the intercellular space. From their morphological characteristics it was concluded that these originated from secretory granule cores, which are discharged from the parenchymal cells into the intercellular space by exocytosis, and it was suggested that discharged granule cores may retain their spherical shape until they fuse to form a flat conglomerate.     

迷走神经刺激对记忆的影响

迷走神经刺激(vagus nerve stimulation, VNS)用于终止癫痫发作已经有二十年的历史.期间VNS也用于难治性抑郁的治疗.在治疗过程中研究者发现VNS 对癫痫、抑郁患者的学习和记忆能力有改善作用,这种改善作用在一些动物和人体实验中也得到证实.但VNS在记忆形成的哪个阶段起作用以及如何起作用的具体机制尚不十分清楚.因此,进一步了解VNS对记忆的影响及作用机制有利于探讨记忆形成的生理机制,也为临床治疗特异性记忆障碍和相关神经精神疾病提供新的思路和有益补充.本文综述了近十几年来VNS对记忆的影响及相关机制.     

Histopathologic features of the vagus nerve after electrical stimulation in swine

This paper describes the histological features of the vagus nerve after its stimulation with an electrostimulation system that is being developed for morbid obesity treatment. An electrostimulation system was implanted laparoscopically around the ventral vagal trunk of five Large White female pigs (49.63+/-1.94 kg.). Vagal nerve stimulation was performed by continuous constant voltage current pulses. Thoracic samples of both ventral and dorsal vagal trunks were obtained thoracoscopically one month after implantation. Animals were sacrificed one month after thoracoscopic vaguectomy. Tissue samples were then harvested from the vagal nerve at the implantation site, 1cm cranial to it, thoracic portion of ventral and dorsal vagal trunks, sub-diaphragmatic dorsal vagal trunk, left and right vagus nerves. Specimens were analysed with light microscope. The severity of the lesions was graded from 0 to 4 (0: no lesion, 1: mild, 2: moderate, 3: severe and 4: extremely severe), taking into account fibrosis, vascularization, necrosis, fiber degeneration and inflammation. Electrode implantation resulted in thickened epineurium and endoneural connective tissue. The greatest lesion score was evidenced at the leads implantation site in the ventral vagal trunk, followed by, in order of decreasing lesion severity, left vagus nerve, thoracic portion of ventral vagal trunk, subdiaphragmatic dorsal vagal trunk, thoracic portion of dorsal vagal trunk and right vagus nerve. The stimulation device used in this study caused connective tissue growth, greatest in the samples located closer to the implantation site. However, there was no sign of altered vascularization in any studied specimen.     

弱电刺激大鼠迷走神经中枢端在海马CA1区产生周期性theta电振荡

目的：观察弱电刺激迷走神经中枢端对正常大鼠海马细胞放电及场电的影响。方法：雄性成年大鼠45只．分离其颈部左侧迷走神经,结扎外周端,弱电（10Hz,0．5ms,1.5～5.0V,15-20／chain）刺激,每5min一次,共20串：记录右侧海马CAI细胞放电及双侧海马CAI场电。结果：双侧场电出现周期性theta电振荡（38／45,84．4％）,伴有theta—on（n=30）和theta—off（n=5）两种形式的非簇状紧张性细胞放电.结论：弱电刺激迷走神经中枢端激活海马CAI区网络,并对网络内细胞放电有紧张性调制作用.     

Effects of isoproterenol treatment on the parathyroid glands in golden hamsters of different ages, with special reference to the frequency of lipid droplets

The frequency of lipid droplets in the parathyroid glands of young, adult and senile golden hamsters after treatment with isoproterenol was investigated. In the parathyroid glands of the young and senile animals the number of lipid droplets increased gradually by 1 h, and thereafter it remained almost unchanged at 3 h after administration. In the glands of adult animals it increased, at first rapidly and then gradually, by 3 h after administration. It is considered that in the parathyroid glands of the golden hamsters stimulated by isoproterenol there is a relationship between the number of lipid droplets and aging.     

Phosphoinositide metabolism in rat superior cervical ganglion, vagus and phrenic nerve: effects of electrical stimulation and various blocking agents

Abstract— Paired vagus nerves, phrenic nerves or superior cervical ganglia from rats were incubated at 37 C for various times in a simple salt solution containing glucose and ³²P_i. One of the pair was usually stimulated electrically for 30 or 60 min. Stimulation of vagus nerve for 30 min increased phosphate incorporation into all the phospholipids studied but the increase was significant only in the case of triphos-phoinositide and diphosphoinositide. This increase was not accompanied by increased labelling of the nucleotide labile phosphate pool. Tetrodotoxin at concentrations sufficient to block transmission had no effect upon phospholipid labelling in vagus or phrenic nerve. Ouabain at blocking concentration did not affect polyphosphoinositide metabolism in vagus nerve but increased [³²P]labelling of the other phospholipids. Hemicholinium-3 increased the labelling of all three phosphoinositides in the sympathetic ganglia but the increase in phosphatidylinositol labelling due to electrical stimulation was not seen in the presence of this inhibitor.     

Effects of short-term treatment with calcium on the parathyroid glands in golden hamsters of different ages, with special reference to large vacuolar bodies.

The effects of different ages on large vacuolar bodies in the parathyroid glands of golden hamsters after short-term treatment with calcium were investigated. In the parathyroid glands of the young and adult animals 15 min and the senile animals 15 and 60 min after administration of calcium, the percent area occupied by large vacuolar bodies was significantly increased as compared to that of the young, adult and senile control animals, respectively. These findings suggest that the percent area occupied by large vacuolar bodies is increased in response to acute hypercalcemia. It is thought that in the parathyroid glands suppressed by hypercalcemia there is a relationship between the percent area occupied by large vacuolar bodies and aging.     

Effects of diabetes and dietary manipulation on rat parotid gland secretory response to sympathetic nerve stimulation.

1. The effects of streptozotocin-diabetes, bulk-diet, low protein diet (8%) and protein-calorie malnutrition on parotid gland response to sympathetic nerve stimulation were studied in male Wistar rats. 2. Mean body weights were considerably less in diabetic and protein-calorie malnourished rats than in the other groups, but parotid gland weight was reduced only in animals placed on a low-protein diet. 3. Salivary flow rate (microliter/min/g tissue) and total protein output (mg secreted/g tissue) were reduced in diabetic rats. 4. Salivary composition was altered in diabetes and protein-calorie restriction, and the specific changes were unique to each condition. 5. Thus, with the possible exception of gland weight the effects of diabetes on parotid gland structure and function are not related to either hyperphagia or nutritional status.     

Electron-microscopic studies on the threshold value of calcium concentration for the release of storage granules and the acceleration of their degradation in the rat parathyroid gland

Summary To determine both a threshold value of calcium concentration (CC) for the release of storage granules and that for the acceleration of degradation of these granules, the rat parathyroid glands were perfused in situ with HEPES-Ringer solutions containing different concentration of Ca²⁺ for 10 min. With perfusates containing 0.83–1.21 mM Ca²⁺ (equivalent to 8–11 mg/dl serum calcium), the number of type-I storage granules (large core) [NSG-I] and that of type-II storage granules (small core) [NSG-II] remained unchanged. With perfusates containing 0.83 mM Ca²⁺ (7.5 mg/dl) or less, however, both NSG-I and NSG-II decreased remarkably and the former was larger than the latter. On the contrary, with perfusates containing 1.27 mM Ca²⁺ (11.5 mg/dl) or more, NSG-II increased and the ratio of NSG-I to NSG-II was changed reversely. We concluded that a thereshold value of CC required for the release of storage granules may be present between 0.88 and 0.83 mM Ca²⁺ (8 and 7.5 mg/dl) and that a threshold value of CC for accelerating the transformation of type-I granules into type-II, the degradation of storage granules, may be situated at about 1.27 mM Ca²⁺ (11.5 mg/dl). Additionally, it was suggested that both prosecretory and storage granules are not only formed at the innermost Golgi cisterna but also at the trans-Golgi network.