Effect of hyperglycaemia on muscarinic M3 receptor expression and secretory sensitivity to cholinergic receptor activation in islets

2014 ◽  
Vol 16 (10) ◽  
pp. 947-956 ◽  
Author(s):  
A. C. Hauge-Evans ◽  
C. Reers ◽  
A. Kerby ◽  
Z. Franklin ◽  
S. Amisten ◽  
...  
Keyword(s):  
Cholinergic Receptor ◽  
Receptor Activation ◽  
Receptor Expression ◽  
M3 Receptor

Cholinergic modulation of synaptic inhibition in the guinea pig hippocampus in vitro: excitation of GABAergic interneurons and inhibition of GABA-release

1993 ◽  
Vol 69 (2) ◽  
pp. 626-629 ◽  
Author(s):  
J. C. Behrends ◽  
G. ten Bruggencate
Keyword(s):  
Guinea Pig ◽  
Synaptic Transmission ◽  
Pyramidal Neurons ◽  
Gaba Release ◽  
Cholinergic Receptor ◽  
Receptor Activation ◽  
Release Mechanism ◽  
Gabaergic Interneurons ◽  
Gamma Aminobutyric Acid

1. The effect of cholinergic receptor activation on gamma-aminobutyric acid (GABA)-mediated inhibitory synaptic transmission was investigated in voltage-clamped CA1 pyramidal neurons (HPNs) in the guinea pig hippocampal slice preparation. 2. The cholinergic agonist carbachol (1-10 microM) induced a prominent and sustained increase in the frequency and amplitudes of spontaneous inhibitory postsynaptic currents (IPSCs) in Cl(-)-loaded HPNs. The potentiation of spontaneous IPSCs was not dependent on excitatory synaptic transmission but was blocked by atropine (1 microM). 3. Monosynaptically evoked IPSCs were reversibly depressed by carbachol (10 microM). 4. The frequency of miniature IPSCs recorded in the presence of tetrodotoxin (0.6 or 1.2 microM) was reduced by carbachol (10 or 20 microM) in an atropine-sensitive manner. 5. We conclude that, while cholinergic receptor activation directly excites hippocampal GABAergic interneurons, it has, in addition, a suppressant effect on the synaptic release mechanism at GABAergic terminals. This dual modulatory pattern could explain the suppression of evoked IPSCs despite enhanced spontaneous transmission.

scholarly journals Endothelin, sex, and pregnancy: unique considerations for blood pressure control in females

2016 ◽  
Vol 310 (8) ◽  
pp. R691-R696 ◽  
Author(s):  
Ellen E. Gillis ◽  
Jennifer M. Sasser ◽  
Jennifer C. Sullivan
Keyword(s):  
Blood Pressure ◽  
Sex Differences ◽  
Blood Pressure Control ◽  
Pressure Control ◽  
Receptor Activation ◽  
Receptor Expression ◽  
Young Females ◽  
Potential Benefits ◽  
Important Pathway ◽  
Potent Vasoconstrictor

Endothelin-1 (ET-1) is a potent vasoconstrictor, and dysregulation of the endothelin (ET) system has been implicated in the development of hypertension. Sex differences in the ET system have been identified in ET receptor expression and activation, levels of ET-1, and downstream mediators of the ET system. More specifically, males have greater ET-1/ETA receptor activation, whereas females exhibit greater ETB receptor activation. These differences have been suggested to contribute to the sex differences observed in blood pressure control, with greater ETB receptor activation in females potentially acting as an important pathway contributing to the lower prevalence of hypertension in young females compared with age-matched males. This hypothesis is further supported by studies in pregnancy; the role of the ET system is enhanced during pregnancy, with dysregulation of the ET system resulting in preeclampsia. Further research is necessary to elucidate the relative roles of the ET system in blood pressure control in both sexes and to further explore the potential benefits of pharmacological ET blockade in women.

Reduced renal dopamine D1 receptor function in streptozotocin-induced diabetic rats

2004 ◽  
Vol 286 (3) ◽  
pp. F451-F457 ◽  
Author(s):  
Aditi Marwaha ◽  
Anees Ahmad Banday ◽  
Mustafa F. Lokhandwala
Keyword(s):  
Atpase Activity ◽  
Sodium Excretion ◽  
Type I Diabetes ◽  
Receptor Activation ◽  
Diabetic Rats ◽  
D1 Receptor ◽  
Skf 38393 ◽  
Receptor Expression ◽  
Type I ◽  
Renal Dopamine

Dopamine, via activation of renal D1 receptors, inhibits the activities of Na-K-ATPase and Na/H exchanger and subsequently increases sodium excretion. Decreased renal dopamine production and sodium excretion are associated with type I diabetes. However, it is not known whether the response to D1 receptor activation is altered in type I diabetes. The present study was designed to examine the effect of streptozotocin-induced type I diabetes on renal D1 receptor expression and function. Streptozotocin treatment of Sprague-Dawley rats caused a fourfold increase in plasma levels of glucose along with a significant decrease in insulin levels compared with control rats. Intravenous administration of SKF-38393, a D1 receptor agonist, caused a threefold increase in sodium excretion in control rats. However, SKF-38393 failed to produce natriuresis in diabetic rats. SKF-38393 caused a concentration-dependent inhibition of Na-K-ATPase activity in renal proximal tubules of control rats. However, the ability of SKF-38393 to inhibit Na-K-ATPase activity was markedly diminished in diabetic rats. D1 receptor numbers and protein abundance as determined by [3H]SCH-23390 ligand binding and Western blot analysis were markedly reduced in diabetic rats compared with control rats. Moreover, SKF-38393 failed to stimulate GTPγS binding in proximal tubular membranes from diabetic rats compared with control rats. We conclude that the natriuretic response to D1 receptor activation is reduced in type I diabetes as a result of a decrease in D1 receptor expression and defective receptor G protein coupling. These abnormalities may contribute to the sodium retention associated with type I diabetes.

scholarly journals The Therapeutic Effect of Active Vitamin D Supplementation in Preventing the Progression of Diabetic Nephropathy in a Diabetic Mouse Model

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Nakhoul Nakhoul ◽  
Tina Thawko ◽  
Evgeny Farber ◽  
Inbal Dahan ◽  
Hagar Tadmor ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Vitamin D ◽  
Diabetic Nephropathy ◽  
Vitamin D Receptor ◽  
Receptor Activation ◽  
Receptor Expression ◽  
Active Vitamin ◽  
Active Vitamin D ◽  
Vitamin D Analog

Background. Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes and is the leading cause of end-stage renal disease (ESRD) and replacement therapy worldwide. Vitamin D levels in DN patients are very low due to the decrease in the synthesis and activity of 1-α hydroxylase in the proximal tubule cells and decrease in the vitamin D receptor abundance. To date, few studies have shown the antioxidant effects of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] on hyperglycemia-induced renal injury. The selective activator of the vitamin D receptor, paricalcitol, reduces proteinuria and slows the progression of kidney injury. The precise mechanism through which vitamin D affects diabetic status and provides kidney protection remains to be determined. Methods. Diabetes mellitus (DM) was induced in 94 8-week-old DBA/2J mice by intraperitoneal injection of streptozotocin (STZ). DM mice were randomly divided into receiving vehicle or treatment with paricalcitol, the active vitamin D analog, 1 week after DM induction or paricalcitol treatment 3 weeks after DM induction. An additional control group of healthy wild-type mice was not treated. Urine albumin, blood urea nitrogen, and creatinine levels were measured before and at the end of the paricalcitol treatment. Periodic acid-Schiff, immunohistochemistry staining, and western blot of the renal tissues of vitamin D receptor, villin, nephrin, and podocin expressions, were analyzed. Results. Paricalcitol treatment restored villin, nephrin, and podocin protein levels that were downregulated upon DM induction, and reduced fibronectin protein level. Vitamin D receptor activation by paricalcitol may reduce proteinuria of DN in mice and alleviate high-glucose-induced injury of kidney podocytes by regulating the key molecules such nephrin-podocin. Conclusions. Paricalcitol treatment was associated with improved structural changes in type 1 diabetic mice including upregulation of vitamin D receptor expression, and decreased fibrosis markers such as fibronectin. These effects may contribute to the consistent benefit of vitamin D analog to slow the deterioration in glomerular function and reduce the risk of ESRD in patients with type 1 and 2 diabetes mellitus. Our results suggest that additional use of paricalcitol may be beneficial in treating patients with diabetes under standard therapeutic strategies.

scholarly journals Modulation of phrenic motoneuron excitability by ATP: consequences for respiratory-related output in vitro

2002 ◽  
Vol 92 (5) ◽  
pp. 1899-1910 ◽  
Author(s):  
Gareth B. Miles ◽  
Marjorie A. Parkis ◽  
Janusz Lipski ◽  
Gregory D. Funk
Keyword(s):  
Pyridoxal Phosphate ◽  
Rapid Onset ◽  
Receptor Activation ◽  
Receptor Expression ◽  
P2x Receptor ◽  
Repetitive Firing ◽  
Burst Amplitude ◽  
Inward Currents ◽  
High Level

On the basis of the high level of P2X receptor expression found in phrenic motoneurons (MN) in rats (Kanjhan et al., J Comp Neurol407: 11–32, 1999) and potentiation of hypoglossal MN inspiratory activity by ATP (Funk et al., J Neurosci 17: 6325–6337, 1997), we tested the hypothesis that ATP receptor activation also modulates phrenic MN activity. This question was examined in rhythmically active brain stem-spinal cord preparations from neonatal rats by monitoring effects of ATP on the activity of spinal C4 nerve roots and phrenic MNs. ATP produced a rapid-onset, dose-dependent, suramin- and pyridoxal-phosphate-6-azophenyl-2′,4′-disulphonic acid 4-sodium-sensitive increase in C4 root tonic discharge and a 22 ± 7% potentiation of inspiratory burst amplitude. This was followed by a slower, 10 ± 5% reduction in burst amplitude. ATPγS, the hydrolysis-resistant analog, evoked only the excitatory response. ATP induced inward currents (57 ± 39 pA) and increased repetitive firing of phrenic MNs. These data, combined with persistence of ATP currents in TTX and immunolabeling for P2X2 receptors in Fluoro-Gold-labeled C4 MNs, implicate postsynaptic P2 receptors in the excitation. Inspiratory synaptic currents, however, were inhibited by ATP. This inhibition differed from that seen in root recordings; it did not follow an excitation, had a faster onset, and was induced by ATPγS. Thus ATP inhibited activity through at least two mechanisms: 1) a rapid P2 receptor-mediated inhibition and 2) a delayed P1 receptor-mediated inhibition associated with hydrolysis of ATP to adenosine. The complex effects of ATP on phrenic MNs highlight the importance of ATP as a modulator of central motor outflows.

scholarly journals Hearing Loss Alters Serotonergic Modulation of Intrinsic Excitability in Auditory Cortex

2010 ◽  
Vol 104 (5) ◽  
pp. 2693-2703 ◽  
Author(s):  
Deepti Rao ◽  
Gregory J. Basura ◽  
Joseph Roche ◽  
Scott Daniels ◽  
Jaime G. Mancilla ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Auditory Cortex ◽  
Sensorineural Hearing Loss ◽  
Pyramidal Cell ◽  
Receptor Activation ◽  
Sensorineural Hearing ◽  
Receptor Expression ◽  
Intrinsic Excitability ◽  
Receptor Subtypes ◽  
Cell Excitability

Sensorineural hearing loss during early childhood alters auditory cortical evoked potentials in humans and profoundly changes auditory processing in hearing-impaired animals. Multiple mechanisms underlie the early postnatal establishment of cortical circuits, but one important set of developmental mechanisms relies on the neuromodulator serotonin (5-hydroxytryptamine [5-HT]). On the other hand, early sensory activity may also regulate the establishment of adultlike 5-HT receptor expression and function. We examined the role of 5-HT in auditory cortex by first investigating how 5-HT neurotransmission and 5-HT2 receptors influence the intrinsic excitability of layer II/III pyramidal neurons in brain slices of primary auditory cortex (A1). A brief application of 5-HT (50 μM) transiently and reversibly decreased firing rates, input resistance, and spike rate adaptation in normal postnatal day 12 (P12) to P21 rats. Compared with sham-operated animals, cochlear ablation increased excitability at P12–P21, but all the effects of 5-HT, except for the decrease in adaptation, were eliminated in both sham-operated and cochlear-ablated rats. At P30–P35, cochlear ablation did not increase intrinsic excitability compared with shams, but it did prevent a pronounced decrease in excitability that appeared 10 min after 5-HT application. We also tested whether the effects on excitability were mediated by 5-HT2 receptors. In the presence of the 5-HT2-receptor antagonist, ketanserin, 5-HT significantly decreased excitability compared with 5-HT or ketanserin alone in both sham-operated and cochlear-ablated P12–P21 rats. However, at P30–P35, ketanserin had no effect in sham-operated and only a modest effect cochlear-ablated animals. The 5-HT2-specific agonist 5-methoxy- N, N-dimethyltryptamine also had no effect at P12–P21. These results suggest that 5-HT likely regulates pyramidal cell excitability via multiple receptor subtypes with opposing effects. These data also show that early sensorineural hearing loss affects the ability of 5-HT receptor activation to modulate A1 pyramidal cell excitability.

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