JNK/c-Jun signaling pathway mediates arginine vasopressin neuron regeneration by promoting cytoskeleton reconstruction in rats with electrical lesions of the pituitary stalk / 南方医科大学学报

OBJECTIVE@#To investigate the mechanism by which doublecortin promotes the recovery of cytoskeleton in arginine vasopressin (AVP) neurons in rats with electrical lesions of the pituitary stalk (PEL).@*METHODS@#Thirty-two SD rats were randomized into PEL group with electrical lesions of the pituitary stalk through the floor of the skull base (=25) and sham operation group (=7), and the daily water consumption (DWC), daily urine volume (DUV) and urine specific gravity (USG) of the rats were recorded. Four rats on day 1 and 7 rats on each of days 3, 7 and 14 after PEL as well as the sham-operated rats were sacrificed for detection of the expressions of β-Tubulin (Tuj1), doublecortin and caspase- 3 in the AVP neurons of the supraoptic nucleus using immunofluorescence assay and Western blotting.@*RESULTS@#After PEL, the rats exhibited a typical triphasic pattern of diabetes insipidus, with the postoperative days 1-2 as the phase one, days 3-5 as the phase two, and days 6-14 as the phase three. Immunofluorescent results indicated the repair of the AVP neurons evidenced by significantly increased doublecortin expressions in the AVP neurons following PEL; similarly, the expression of Tuj1 also increased progressively after PEL, reaching the peak level on day 7 after PEL. The apoptotic rates of the AVP neurons exhibited a reverse pattern of variation, peaking on postoperative day 3 followed by progressive reduction till day 14. Western blotting showed that the expressions of c-Jun and p-c-Jun were up-regulated significantly on day 3 ( < 0.05) and 7 ( < 0.01) after PEL, while an upregulated p-JNK expression was detected only on day 3 ( < 0.05), as was consistent with the time-courses of neuronal recovery and apoptosis after PEL.@*CONCLUSIONS@#JNK/c-Jun pathway is activated after PEL to induce apoptosis of AVP neurons in the acute phase and to promote the repair of neuronal cytoskeleton by up-regulation of doublecortin and Tuj1 expressions.

Effects of nitric oxide on magnocellular neurons of the supraoptic nucleus involve multiple mechanisms

Physiological evidence indicates that the supraoptic nucleus (SON) is an important region for integrating information related to homeostasis of body fluids. Located bilaterally to the optic chiasm, this nucleus is composed of magnocellular neurosecretory cells (MNCs) responsible for the synthesis and release of vasopressin and oxytocin to the neurohypophysis. At the cellular level, the control of vasopressin and oxytocin release is directly linked to the firing frequency of MNCs. In general, we can say that the excitability of these cells can be controlled via two distinct mechanisms: 1) the intrinsic membrane properties of the MNCs themselves and 2) synaptic input from circumventricular organs that contain osmosensitive neurons. It has also been demonstrated that MNCs are sensitive to osmotic stimuli in the physiological range. Therefore, the study of their intrinsic membrane properties became imperative to explain the osmosensitivity of MNCs. In addition to this, the discovery that several neurotransmitters and neuropeptides can modulate their electrical activity greatly increased our knowledge about the role played by the MNCs in fluid homeostasis. In particular, nitric oxide (NO) may be an important player in fluid balance homeostasis, because it has been demonstrated that the enzyme responsible for its production has an increased activity following a hypertonic stimulation of the system. At the cellular level, NO has been shown to change the electrical excitability of MNCs. Therefore, in this review, we focus on some important points concerning nitrergic modulation of the neuroendocrine system, particularly the effects of NO on the SON.

Whole transcriptome organisation in the dehydrated supraoptic nucleus

The supraoptic nucleus (SON) is part of the central osmotic circuitry that synthesises the hormone vasopressin (Avp) and transports it to terminals in the posterior lobe of the pituitary. Following osmotic stress such as dehydration, this tissue undergoes morphological, electrical and transcriptional changes to facilitate the appropriate regulation and release of Avp into the circulation where it conserves water at the level of the kidney. Here, the organisation of the whole transcriptome following dehydration is modelled to fit Zipf's law, a natural power law that holds true for all natural languages, that states if the frequency of word usage is plotted against its rank, then the log linear regression of this is -1. We have applied this model to our previously published euhydrated and dehydrated SON data to observe this trend and how it changes following dehydration. In accordance with other studies, our whole transcriptome data fit well with this model in the euhydrated SON microarrays, but interestingly, fit better in the dehydrated arrays. This trend was observed in a subset of differentially regulated genes and also following network reconstruction using a third-party database that mines public data. We make use of language as a metaphor that helps us philosophise about the role of the whole transcriptome in providing a suitable environment for the delivery of Avp following a survival threat like dehydration.

Arginine vasopressin (AVP) expressional changes in the hypothalamic paraventricular and supraoptic nuclei of stroke-prone spontaneously hypertensive rats / 대한해부학회지

Arginine vasopressin (AVP) is a neuropeptide with vasoconstrictive, antidiuretic, cardiovascular regulative and hepatic glycogenolysis effects, that also affects other behaviors including modulating learning. A number of studies on AVP regulation have been conducted in various metabolic diseases (disorders). In this study, the immunoreactivities of AVP in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) and mRNA expressions in the hypothalamus were investigated by immunohistochemistry and quantitative real-time PCR (RT-qPCR) in stroke-prone spontaneously hypertensive rats at different ages (i.e., at postnatal months [PM] 1, 8, and 12). Blood glucose levels in the PM 8 group were higher than in the other groups. However, cresyl violet positive neurons were detected in the PVN and SON of all animals, and numbers of cresyl violet positive neurons were similar in all aged groups. In addition, AVP immunoreactivity was detected in the PVN and SON of all age groups, and AVP immunoreactivity and mRNA expression levels were found to be increased in proportion to age by immunohistochemistry and RT-qPCR. These results suggest that the diabetic condition is temporally generated after hypertension has developed. Furthermore, our findings suggest that increased AVP expressions in the hypothalamic PVN and SON are associated with hypertension by age.

Effects of exogenous estrogen on the distribution of nitric oxide synthase positive neurons in supraoptic nuclus of hypothalamus of ovariectomized female rats / 解剖学报

Objective To observe how exogenous estrogen influences the distribution and the expression of NOS positive neurons in the supraoptic nuclei of hypothalamus in the overiectomized female rats. Methods The 2-3-month-old female rats(n=40) were selected as the healthy and nulli-copulatory experimental animals. Rats were divided into following groups: normal control group(n=10), ovariectomized control group(n=10), and two experimental groups that have been injected with estrogen for post-operative 40 days(n=10) and for post-operative 70 days(n=10). Finally, all the animals were infused and the brains were removed. Immunohistochemical (SABC) method was adopted to count the number of NOS poitive neurons and observed the NOS poitive neuronal morphology under the light microscope. The image analysis system was used to test the average gray value of immunoreactivity in NOS positive neurons. Results In the ovariectomized control group, the density of NOS positive neurons in supraoptic nucleus was significantly increased and their shapes were bigger than that of the normal control group(P<0.05). The density and the form of the NOS positive neurons in supraoptic nucleons had no apparent difference between the estrogen for post-operative 40 days group and the ovariectomizeed control group(P>0.05).In the group after estrogen-injection 2 months compared with the normal control group, and the ovariectomized control group, both of the NOS positive neurons' density and the size become significantly decreased, and the staining of cells was lesser in the group injected with estrogen for post-operation 70 days. Conclusion The present results suggest that exogenous estrogen may influence the distribution and the expression of NOS positive neurons in supraoptic nucleus of hypothalamus of ovariectomized female rats.

Morphological Changes in Vasopressin-immunoreactive Neurons in the Hypothalamus of the Aged Rats / 체질인류학회지

The role of neuropeptides in the central nervous system (CNS) has received increasing attention. Numerous peptide molecules are found in the mammalian CNS and many of them are thought to act as either neurotransmitters or neuromodulators. The neuropeptides found in high concentration in the hypothalamus include vasopressin (VP), vasoactive intestinal polypeptide, somatostatin, and oxytocin. The main approches to assess the involvement of neuropeptides can be focused on functions affecting the aging of the brain. Morphological aging of the CNS has been characterized by degenerative changes of fiber connections and cell loss, although degeneration does not always occur to the same extent throughout various parts of the brain and, moreover, varies for different cell types. Despite of many studies in VP containing neurons , there exist discrepancies in results about the changes of aged rat brain. The aim of the present study is, therefore, to investigative possible changes in the number and morphology of VPimmunoreactive neurons with aging in each area of the hypothalmus of the aged rats. As a result, the number of VP-immunoreactive neurons was decreased in hypothalamus nucleus of aged group. Especially, in VP-immunoreactive neurons of hypothalamus, the size of neuronal cell body and nuclei in aged group is larger than in young group and the fiber density of immunoreactivity neurons of median eminance (ME) in aged group is stronger than in young group. But, the total number of VP-immunoreactive neurons in the suprachiasmatic nucleus (SCN) of the aged group is larger than in the young group. These studies indicate the involvement of VP-immunoreactive neurons in aging process of hypothalamus, and aging process may affect the synthesis of VP in the neurons of hypothalamic nuclei. Whereas, in VP expression, aging process induces an enlargement of the cell size of surviving neurons to compensate.

Effect of Chronic Alcohol Intake on Vasopressin and Oxytocin-containing Neurons in the Paraventricular and Supraoptic Nucleus of the Rat Hypothalamus / 체질인류학회지

Chronic alcohol intake can profoundly modify the neuronal activity and the morphologic structure of hypothalamic nucleus in the rat brain. The aim of the present study is to observe the effects of chronic alcohol intake on expression of vasopressin and oxytocin in the paraventricular and supraoptic nucleus in the rat hypothalamus. Experimental rats (n=14) were divided into control group and chronic alcohol group. Chronic alcohol group was induced via daily liquid alcohol intake for 6 months beginning at 8 weeks of age. As a result, the number of vasopressin and oxytocin-containing neurons was decreased in the paraventricular and supraoptic nucleus in chronic alcohol group. Especially, the number of vasopressin-containing neurons of chronic alcohol group was significantly decreased in the paraventricular nucleus. Chronic alcohol intake produced significant changes in the volume of the cell bodies and their nucleus in neurons of the paraventricular and supraoptic nucleus. Particularly, the size of nucleus of vasopressin-containing neurons in chronic alcohol group was larger than in control group. These results show that chronic alcohol intake may affect the synthesis of vasopressin and oxytocin in the neurons of hypothalamic nuclei. Whereas, chronic alcohol intake induces an enlargement of the cell size of surviving neuron to compensate.

Effects of sodium nitroprusside on glutamate-induced responses of supraoptic nucleus neurons in vitro / 中国药理学通报

Aim To realize the modulatory actions of nitric oxide(NO) on supraoptic nucleus(SON)neurons by observing the effects of NO donor sodium nitroprusside(SNP) on the SON neurons. Methods The cell electrophysiology properties were obtained by the intracellular recording techniques from the SON neurons in adult rat hypothalamic slices. Results Local pressure ejection of glutamate induced depolarizing responses with decrease of input resistance, concentration- and membrane potential-dependent properties in 12 SON neurons. The amplitude and duration of glutamate responses were suppressed by bath of SNP in 67% of tested cells(P

Expressions of NMDAR2 and GLAST in supraoptic nucleus and hippocampal gyrus under sleep deprivation in young rats / 医学研究生学报

Objective: To observe the expressions of NMDAR2 and GLAST in the hippocampal gyrus and supraoptic nucleus(SON) under sleep deprivation in young rats.Methods: The changes in expressions of NMDAR2 and GLAST in SON and hippocampal gyrus under sleep deprivation in younger rats were observed by immunohistochemistry method. Results:The expressions of NMDAR2 and GLAST in SON and the hippocampal gyrus were significantly increased on the 3rd day of sleep deprivation,even more sigificantly on the 5th day,decreased gradually on 7th day,and became similar to those of control group on the 14th day.Conclusion: Sleep deprivation can affect the expressions of NMDAR2 and GLAST in the hippocampal gyrus and supraoptic nucleus,but the effect diminisshes gradually with prolonged time,which may be associated with self-regulation and self-protection of the central nervous system.

Influence of optic nerve transection on the expression of Nogo A/B and NgR in hypothalamic supraoptic nucleus neurocytes of rats / 解放军医学杂志

Objective To study the influence of bilateral optic nerve transections on the expression of Nogo A/B and NgR in hypothalamic supraoptic nucleus neurocytes of rats in order to elucidate the possible regulatory mechanisms of supraoptic nucleus regeneration.Methods Twelve adult SD rats were randomly assigned into 2 groups(6 each): control group and optic nerve division group(transection of bilateral optic nerves).Sham operation was done in,rats of the control group without transection of sptic nerves.The rats' brains were removed from both groups 7 days after surgery,and then frozen sections of the brains were made.Different antibodies and fluorescent probe dyes were used to label Nogo-A/B and NgR proteins in the hypothalamic supraoptic nucleus neurocytes.And then laser-confocal microscopy was used to observe these proteins.Results No Nogo-A/B and NgR proteins were expressed in neurocytes of hypothalamic supraoptic nucleus in control group.However,Nogo-A/B and NgR proteins were positively expressed around the nuclei of neurocytes in rats of the optic nerve division group 7 days after bilateral optic nerve transection in the said area Conclusions Nogo-A/B and NgR may participate in the regeneration regulation of supraoptic nucleus neurocytes after injury.However,there must be other factors also involved in the regeneration regulation mechanisms.The existence of these factors might explain the strong activity of regeneration of supraoptic nucleus neurocytes after injury even with the existence of the major axon regeneration inhibitor Nogo-A/B and its receptor NgR in the microenvironment.

Inhibitory and excitatory effects of sodium nitroprusside on supraoptic nucleus neurons in vitro / 中国临床药理学与治疗学

AimTo realize the regulatory actions of nitric oxide(NO) on supraoptic nucleus (SON) neurons by observing the effects of NO donor sodium nitroprusside(SNP) on SON neurons. Methods The cell electrophysioloical properties were obtained by the intracellular recording techniques from the SON neurons in adult rat hypothalamic slices. Results In 11 silent cells, superfusion of SNP(1 mmol · L-1) for 3～5 min resulted in the depolarization response with a decrease of membrane resistance and time constant(P＜0.05) in 55% of cells, while hyperpolarization with an increase of membrane resistance in 45 % of neurons. In 73% of tested cells, SNP also decreased the amplitude, overshoot, firing frequency and slope of current-voltage curve, and increased the afterhyperpolarization of action potentials evoked by intracellular depolarizing current pulses(P ＜0.05).However, SNP enhanced the spontaneous firing in 67% of 6 tested cells with spontaneous activities. ConclusionSNP presents an inhibitory or excitatory effect on SON neurons in aneurontype-andfunctionalstate-dependent manner, which suggests that NO may exhibit adverse regulatory actions on SON neurons.

Inhibitory and excitatory effects of sodium nitroprusside on supraopticnucleus neurons in vitro / 中国临床药理学与治疗学

Aim To realize the regulatory actions of nitric oxide(NO) on supraoptic nucleus (SON)neurons by observing the effects of NO donor sodium nitroprusside(SNP) on SON neurons.Methods The cell electrophysioloical properties were obtained by the intracellular recording techniques from the SON neurons in adult rat hypothalamic slices.Results In 11 silent cells, superfusion of SNP(1 mmol?L-1) for 3～5 min resulted in the depolarization response with a decrease of membrane resistance and time constant(P

Effects of hypothalamic supraoptic ADH neurons at different times after hypophysectomy in Wistar rats / 中国病理生理杂志

AIM:To observe the effects of supraoptic ADH neurons and central diabetes insipidus(CDI)in Wistar rats at different times after hypophysectomy.METHODS:Hypophysectomy was undergone by stereotaxic instrument.Water intake,urine output and urine specific gravity(SG)were observed each day.The survival rate of supraoptic ADH neurons was determined by immunofluorescence after hypophysectomy at different times.RESULTS:The rats manifested triphasic CDI after hypophysectomy.The average water intake in experiment group was 73.9 mL vs 30.9 mL in control group(P0.05),but the cellular body hypertrophy appeared.The survival rate at 10th day was 72%(P0.05),but they were all less than the 10th day(P

Effects of Dehydration on Vasopressin and Oxytocin Immunoreactive Neurons of the Hypothalamus in the Mongolian Gerbil / 대한해부학회지

The effects of dehydration on vasopressin and oxytocin immunoreactive neurons in the hypothalamus was investigated by using a immunohistochemistry. Adult Mongolian gerbil[Meriones unguiculates] were deprived of drinking water. Dehydrated animals were sacrificed on the 7th, 14th and 21st day of water retriction. The results are as follows : 1. The body weights were decreased about 1.8% daily. On the 21st day of dehydration, they were shown up to 45% compare to the control. 2. In the hypothalamus of the control group, majority of vasopressin and oxytocin immunoreactive neurons were located in the supraoptic and paraventricular nuclei. 3. Changes due to dehydrated stimulation were mainly observed in vasopressin immunoreactive neurons. And these changes in supraoptic nuclei were more severe than those in paraventricular nucleus. Size of vasopressin immunoreactived cells and of areas were increased as to proceed the dehydration. The numbers of those were increased on the 7th day of dehydration, and then they were continously decreased. 4. Although oxytocin immunoreactive neurons were slightly changed in numbers during dehydration, they were not shown conspicuous changes compare to vasopressin immunoreactive neurons. Thus it is appeared that vasopressin secretory neurons in the hypothalamus of Mongolian gerbil are affected by osmotic stress induced dehydration while oxytocin neurons may be affected by other factors.

The Effect of Stimulation of Supraoptic Nucleus on Analgesia and Electroacupuncture Analgesia in Rats / 第二军医大学学报

The effects of electro-and chemo-stimulating (ES, CS) supraoptic nucleus (SON) on analgesia and electroacupuncture (EA) analgesia were observed using potassium inotophoresis induced tail-flick in rats. The results showed that: different electrical current (12.5 ~ 50 ?A) stimulating SON elevated the PT (P

Changes of Oxytodn Content in Rats upon Electroacupuncture of “Zusanli” / 第二军医大学学报

In this study, radioimmunoassay (RIA) was performed to measure the change of immunoreactive-oxytocin (ir-OT) content in rat brain' nuclei related pain modulation, spinal cord, pituitary, adrenal gland and plasma by electroacupuncture "Zusanli" (EA) for 30rnin or pain stimulation for 2min. In the EA group, OT content was decreased greatly in the hypothalamic supraoptic N., while increased significantly in the hypothalamic ventromedial N., raphe magnus N., globus pallidus, spinal cord and adrenal gland, and there were no significant change in the hypothalamic paraventricular N., raphe dorsal N., locus ceruleus, pituitary arid plasma. There were also significant changes of OT content in rat brain, spinal cord and pituitary in the pain stimulation group, which are different from those of the EA group. The above results suggest that the changes of OT content in the EA group are specific, and provide evidence for involvement of endogenous OT in the central nervous system in acupuncture analgesia

THE MECHANISMS OF ASTROCYTES MODULATING NEURONS IN RAT SUPRAOPTIC NUCLEUS INDUCED BY HYPOTONIC STIMULATION / 解剖学报

Objective To investigate the mechanisms of astrocytes modulating neurons in rat supraoptic nucleus induced by hypotonic stimulation and the effect of 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1dioxide HCl(TAG,a antagonist for taurine) or carbenoxolone(CBX,a gap junction blocker)on the responses of astrocytes and neurons in SON.Methods Adult male Sprague-Dawley rats were divided into four groups: the control group was injected with 5.5ml/kg 0.9% NaCl solution into the caudal vein;the hypotonic group was injected with 5.5 ml/kg hypo-saline(0.83% glucose plus 0.3% NaCl);TAG + hypotonic and CBX + hypotonic groups were injected with TAG(100?mol/L) or CBX(10g/L) into the lateral ventricle respectively,and were injected 2 hours later with hypotonic saline into the caudal vein.With anti-Fos,anti-vasopressin(VP),anti-glycine receptor(GlyR),anti-glial fibrillary acidic protein(GFAP) and anti-connexin43(Cx43) immunofluorescent staining methods,the responses of neurons and astrocytes in SON were studied.Results In control rats,Fos-,VP-,and GlyR-expression in the neurons and GFAP-or Cx43-expression in the astrocytes were lower.In hypotonic rats,GFAP-,Cx43-and GlyR signals were more than those in control rats,while Fos-and VP-signals were less.Compared with those in hypotonic rats in TAG + hypotonic or CBX + hypotonic rats,GFAP-and Cx43-signals in the astrocytes were the same,GlyR-signals in the neurons decreased,and Fos-and VP-signals increased.Conclusion Hypotonic stimulation activates SON astrocytes,which then release taurine through gap junction signaling to the neurons and inhibit the release of VP from the neurons.