Sympathetic Nerve Transection Research Articles

Voluntary Corn Oil Ingestion Increases Energy Expenditure and Interscapular UCP1 Expression Through the Sympathetic Nerve in C57BL/6 Mice.

Previously, it has been found that corn oil ingestion activates both the gustatory system and brain reward system, stimulating motivation for eating. In the present study, the effect of voluntary corn oil ingestion on body weight gain and energy metabolism in mice is investigated. Voluntary corn oil ingestion with normal chow feeding does not lead to higher body weight than that of only the chow-fed control group. Mice that ingested corn oil have a higher total caloric intake and energy expenditure than did mice in the control group. Further, voluntary corn oil ingestion significantly upregulates Ucp1 mRNA and protein in interscapular brown adipose tissue (IBAT). Finally, the sympathetic nerve connected to IBAT was surgically transacted, then the body weight is measured for 8 weeks. IBAT sympathetic nerve transection surgery does not affect the body weight gain and food intake; however, when mice ingested corn oil, it induces significant body weight gain without changing the total caloric intake. IBAT sympathetic nerve transection surgery significantly suppresses UCP1 upregulation by corn oil ingestion. The present data suggest that corn oil ingestion activates IBAT through the sympathetic nerve, upregulating UCP1 expression and increasing energy expenditure.

Sympathetic Neurotransmission Increases Local TGF-beta-2 in the Eye and Supports Ocular Inflammation (P07.250)

Objective: To investigate the role of local sympathetic neurotransmission in ocular inflammation. Background We recently demonstrated that surgical transection of sympathetic nerves to the eye leads to a complete disruption of ocular immune privilege in association with a significant reduction in the intraocular expression of the immunosuppressive cytokine transforming growth factor beta (TGF-β). Here we test the hypotheses that expression of intraocular TGF-β is regulated by sympathetic nerves through the stimulation of adrenergic receptors, and that this interaction modifies the course of local inflammation. Design/Methods: Adult male mice were used for all experiments. TGF-β2 (the predominant TGF-β ocular isoform) gene expression was quantified by EvaGreen RT-PCR, while the corresponding protein level was quantified by ELISA. Adrenergic receptors able to induce TGF-β2 expression were identified through a combination of topical and systemic administration of adrenergic agonists and antagonists, and similar treatments of explants and primary cells in culture. The co-expression of adrenergic receptors and TGF-β in the eye was investigated by two-color tissue immunofluorescence. Finally, we tested the clinical significance of our findings using murine endotoxin-induced uveitis (EIU), a well-described model of acute ocular inflammation. Results: Alpha-1 adrenergic receptor stimulation in vivo and in vitro led to a significant up-regulation of TGF-β2 in ocular tissues and cells. Immunofluorescence studies determined that alpha-1 adrenergic receptors are found on the surface of TGF-β-producing cells in the vicinity of the anterior chamber, including corneal endothelial, iris pigment epithelial, and lens capsule cells. Importantly, induction of TGF-β2 by alpha-1 adrenergic agonists exacerbated EIU. Conclusions: Stimulation of α1 adrenergic receptors in the eye results in the increased expression of TGF-β2, which paradoxically supports inflammation. These findings suggest that sympathetic dysfunction and systemic sympathomimetic medications could play an important role in inflammatory diseases of the eye. Supported by: Startup funds from the Herbert Wertheim College of Medicine. Disclosure: Dr. Vega has received personal compensation for activities with Excel Medical Education. Dr. Fatmi has nothing to disclose. Dr. Masli has nothing to disclose. Dr. Turpie has nothing to disclose. Dr. Agoulnik has nothing to disclose. Dr. Bowden has nothing to disclose. Dr. Montero has nothing to disclose.

Induction of neuronal nitric oxide synthase by sympathetic denervation is mediated via α2-adrenoceptors in the jejunal myenteric plexus

Nitric oxide (NO) is an important nonadrenergic, non-cholinergic (NANC) inhibitory neurotransmitter in the gastrointestinal tract. In previous studies, neuronal nitric oxide synthase (nNOS) in the jejunal myenteric plexus, a key enzyme responsible for the release of NO, has been demonstrated to increase after splanchinic ganglionectomy (sympathetic nerve transection). The α2-adrenoceptor is known to be one of the most important receptors which controls intestinal motility. In the present study, we examined the effect of application of the α2-adrenoceptor agonist, clonidine hydrochloride, on nNOS expression in the rat jejunal myenteric plexus after splanchinic ganglionectomy. Clonidine (0.1–1 mg/kg, i.p.) or saline was administered for 5 days after the splanchinic ganglionectomy. The nNOS expression and nNOS mRNA were detected by immunohistochemistry and in situ hybridization for nNOS mRNA, respectively. In the rats treated with vehicle after the splanchinic ganglionectomy, nNOS expression in the myenteric plexus significantly increased compared with sham-operated rats. The increases in nNOS protein and mRNA after splanchinic ganglionectomy were significantly reversed by clonidine treatment. Clonidine-treated naive rats showed no difference in nNOS expression compared with sham-operated rats. These data suggest that nNOS expression in the jejunal myenteric plexus after splanchinic ganglionectomy is regulated by the α2-adrenoceptor and that the α2-adrenoceptor may play an important role in abnormal intestinal motility following splanchinic ganglionectomy in rat jejunum.

Autoinhibitory function of the sympathetic prejunctional neuropeptide Y Y 2 receptor evidenced by BIIE0246

The significance of neuropeptide Y Y 2 receptors in sympathetic nonadrenergic transmission was investigated using the novel selective antagonist BIIE0246 (( S)- N2-[[1-[2-[4-[( R, S)-5,11-dihydro-6(6 h)-oxodibenz[ b, e]azepin-11-yl]-1-piperazinyl]-2-oxoethyl]cyclopentyl]acetyl]- N-[2-[1,2-dihydro-3,5 (4 H)-dioxo-1,2-diphenyl-3 H-1,2,4-triazol-4-yl]ethyl]-argininamide). In anaesthetized pigs pretreated with reserpine, and after transection of sympathetic nerves (depleted of noradrenaline), electrical stimulation of renal and splanchnic sympathetic nerves evoked vasoconstriction in, and overflow of neuropeptide Y-like immunoreactivity from, kidney and spleen, respectively. In the presence of BIIE0246, the nerve-evoked overflows of neuropeptide Y-like immunoreactivity were markedly increased and the splenic vasoconstrictor response prolonged. In addition, BIIE0246 caused splenic vasodilatation per se in this model where basal levels of circulating neuropeptide Y exceed 40 pM. It is concluded that endogenous neurogenical neuropeptide Y regulates its own release via activation of sympathetic prejunctional inhibitory neuropeptide Y Y 2 receptors in both spleen and kidney in the reserpinized pig. Moreover, when circulating levels of neuropeptide Y are moderately increased, activation of neuropeptide Y Y 2 receptors seems to contribute to basal splenic vascular tone.

Pharmacology of H 394/84, a dihydropyridine neuropeptide Y Y 1 receptor antagonist, in vivo

The object of the present paper was to investigate the in vivo pharmacological profile of the dihydropyridine neuropeptide Y Y 1 receptor antagonist 1,4-Dihydro-4-[3-[[[[3-[spiro(indene-4,1′-piperidin-1-yl)]propyl]amino]carbonyl]amino]phenyl]-2,6-dimethyl-3,5-pyridine dicarboxylic acid, dimethylester (H 394/84). The renal vasoconstrictor response to neuropeptide Y in anaesthetized rats was dose-dependently antagonized by H 394/84 (ID 50 value=41±4 nmol/kg/min), whereas the renal vascular responses to noradrenaline and angiotensin II were only slightly affected by H 394/84 (500 nmol/kg/min). In pigs pretreated with reserpine and transection of sympathetic nerves (depleted of noradrenaline), H 394/84 dose-dependently antagonized renal and femoral vasoconstrictor responses evoked by sympathetic nerve activation (neuronally released neuropeptide Y) and exogenous neuropeptide Y. Significant inhibition was seen already at 1.0 nmol/kg/min, when plasma levels of the antagonist reached 29±4 nM. Around 70% of the antagonism remained 90 min after H 394/84 was given. The disposition of H 394/84 fits a biexponential model with initial and terminal half-lives of 2.6 and 48 min, respectively. H 394/84 (100 nmol/kg/min) did not inhibit vascular responses to neuropeptide Y Y 2 receptor-, α−adrenoceptor- or purinoceptor-activation in the pig in vivo. It is concluded that H 394/84 is a potent neuropeptide Y Y 1 receptor antagonist with rather long duration of action in vivo. The selectivity and specificity in vivo is more than 100-fold, and H 394/84 antagonizes vascular responses to exogenous and endogenous, neuronally released, neuropeptide Y with similar potency.

In vivo characterization of the novel neuropeptide Y Y1 receptor antagonist H 409/22.

We studied the effects of the novel neuropeptide Y (NPY) Y1 receptor antagonist H 409/22, and its inactive enantiomer H 510/45, on vascular responses evoked by endogenous and exogenous NPY in the pig in vivo. H 409/22 and H 510/45 were given as 30-min infusions, and the antagonistic effects and circulating plasma concentrations were measured. The initial and terminal half-lives of H 409/22 in plasma were approximately 3 and 30 min, respectively. In pigs pretreated with reserpine and transection of sympathetic nerves (depletion of noradrenaline), sympathetic nerve stimulation evoked nonadrenergic vasoconstrictor responses in kidney and hindlimb, mediated by neuronally released NPY. Significant inhibition of these vasoconstrictor responses, as well as of vascular responses to injections of exogenous NPY, were seen during a low-dose infusion of H 409/22 (1.8 nmol/kg/min), when plasma levels of the antagonist reached 77 +/- 8 nM. Greatest inhibitory effects were seen at the highest dose of H 409/22 (180 nmol/kg/min, giving plasma levels of 7.4 +/- 0.6 microM) when all vascular responses evoked by NPY were strongly attenuated or largely abolished. H 510/45 did not affect any of the vascular responses studied. It is concluded that H 409/22 potently and dose-dependently antagonizes vascular responses to exogenous and endogenous NPY in the pig, and thus represents an interesting tool for studies on NPY Y1 receptor-mediated effects in vivo.

Effects of ouabain on in situ cardiac sympathetic nerve endings

Using dialysis technique, the effects of ouabain on in situ cardiac sympathetic nerve endings were examined in anesthetized cats. Dialysis probes were implanted in the left ventricular myocardium, and the concentration of dialysate norepinephrine (NE) was used as an indicator of NE output at the cardiac sympathetic nerve ending. Locally applied ouabain dose-dependently (1, 10, 100 μM) increased dialysate NE levels. This finding suggested that ouabain causes an increase in NE efflux without any requirement for prior mobilization of NE from vesicular stores. Transection of sympathetic nerves innervating the heart, was without effect on the ouabain (100 μM)-induced increase in NE efflux. Pretreatment with a Ca 2+-channel blocker, ω-conotoxin GVIA (10 μg/kg iv) suppressed the ouabain-induced NE efflux. These data suggested that ouabain opened N-type calcium channels coupled to NE release without centrally mediated neural transmission. Furthermore, ouabain-induced NE efflux was suppressed by pretreatment with desipramine (neuronal NE uptake inhibitor, 100 μM). Our data suggest that the two mechanisms (exocytosis and carrier-mediated outward transport), to the same extent, contributed to the amount of NE efflux evoked by ouabain in in situ cardiac sympathetic nerve endings.

REORGANIZATION OF SOMATO-URETHRAL REFLEXES FOLLOWING SPINAL CORD INJURY IN THE RAT

It is known that reflex activity of the urinary bladder can be inhibited or facilitated by perineal cutaneous stimulation. This study was undertaken to examine the urethral striated (EUS) and smooth muscle responses evoked by perineal cutaneous stimulation in the rat. Urethral perfusion pressure and EUS-EMG were monitored in urethane-anesthetized normal and chronic spinal rats (4-5 weeks after T(8-9) spinalization) of either sex. Somatic perineal stimulation was performed by tactile or pinch stimulation to the perineum. In both normal and chronic spinal rats, perineal stimulation elicited a transient increase in EUS-EMG activity which was abolished following neuromuscular blockade with alpha-bungarotoxin i.v. In normal rats treated with alpha-bungarotoxin perineal stimulation did not elicit a detectable urethral smooth muscle response. However, in chronic spinal rats perineal stimulation increased urethral pressure by smooth muscle contraction in males and decreased urethral pressure by smooth muscle relaxation in females. The evoked urethral smooth muscle contraction in males was significantly reduced or abolished by atropine i.v., but not by sympathetic nerve transection or prazosin i.v., whereas the relaxation in females was significantly reduced or abolished by N-nitro-L-arginine methyl ester (a nitric oxide synthase inhibitor, i.v.). These data indicate that spinal cord injury unmasks somato-urethral smooth muscle reflexes mediated by lumbosacral parasympathetic efferent pathways. The reflexes consist of a nitric oxide-mediated urethral relaxation in females and an atropine-sensitive urethral contraction in male rats.

Reflex pathways controlling urethral striated and smooth muscle function in the male rat.

The organization of vesicourethral reflex mechanisms in the male rat was studied by monitoring intraurethral pressure and the external urethral sphincter (EUS) electromyogram. EUS striated and urethral smooth muscle activities were elicited by reflex isovolumetric bladder contractions evoked by bladder filling or electrical stimulation of nerves in the bladder wall. Evoked EUS bursting activity in normal rats was eliminated in chronic spinal rats and replaced by tonic activity. Reflex urethral smooth muscle activity mediated by an increase in urethral pressure after paralysis of the EUS with alpha-bungarotoxin occurred in normal and chronic spinal rats. The response was significantly larger in chronic spinal (21.3 +/- 3.0 cmH2O) than in normal rats (4.2 +/- 0.7 cmH2O). NG-nitro-L-arginine methyl ester (a nitric oxide synthase inhibitor, 20 mg/kg i.v.) increased the smooth muscle response in normal (5.9 +/- 1.3 cmH2O) and chronic spinal rats (6.9 +/- 1.8 cmH2O). This increase in urethral pressure was not changed by sympathetic nerve transection or prazosin (0.2-0.3 mg/kg i.v.) but was abolished by hexamethonium and reduced 74-89% by atropine. These results indicate that coordinated EUS function (bursting activity) in the male rat is dependent on supraspinal pathways and that the urethral smooth muscle response during voiding is composed of a predominant cholinergic, atropine-sensitive contraction as well as a nitric oxide-mediated relaxation. Both are mediated by activation of parasympathetic pathways and are maintained or significantly larger after spinal cord injury, indicating that they are dependent on spinal reflex pathways.

Repeated renal and splenic sympathetic nerve stimulation in anaesthetized pigs: maintained overflow of neuropeptide Y in controls but not after reserpine

The overflow and the arterial vascular effects of neuropeptide Y (NPY) in response to repeated sympathetic nerve stimulation of kidney and spleen were investigated in anaesthetized pigs. The responses under control conditions were compared to those evoked in pigs with tissue stores of noradrenaline (NA) selectively depleted by reserpine pretreatment combined with sympathetic nerve transection. The renal and splenic sympathetic nerves were repeatedly stimulated at 1 h intervals with one 5 Hz stimulation for 48 s and transmitter overflow determined. Between these stimulations, 5 min stimulations with bursts of 20 Hz (for 1 s every 10 s) were given in order to induce a depletion of nerve transmitter. In the control group, overflow of NPY and NA and vasoconstrictor responses were almost identical for the 5 consecutive stimulations in the kidney, whereas in the spleen the parameters showed a slight tendency to be reduced. In the reserpine-treated group, the initial evoked overflow of NPY was increased 8-fold and 3-fold in the kidney and spleen, respectively, compared to the control group. Upon each subsequent stimulation the overflow decreased gradually, in parallel with the evoked vasoconstrictor response. After a 2 h recovery period no change in evoked overflow of NPY compared to the amount released by the previous stimulation was observed. The present study illustrates, the high capacity of maintenance of not only NA but also NPY overflow and vascular responses in control conditions, whereas the enhanced release of NPY in the absence of NA cannot be maintained. It is therefore possible that the NA-mediated prejunctional feedback mechanism is important for the maintenance of a constant NPY release in situations of high sympathetic activation.

Sympathetic control of antral and pyloric electrical activity in the rabbit.

The effects of section and stimulation of the sympathetic nerve trunk on gastric motility were investigated in conscious and decorticate rabbits. In conscious animals after section of the abdominal splanchnic nerve, rhythm of antral and pyloric bursts was enhanced, becoming more regular, and the period of arrest of the rhythmic bursts, which was usually observed at the end of inflation of the antrum in intact rabbits, was shortened to 33.6 +/- 4.0 s from 112.2 +/- 14.6 s observed before the sympathetic nerve transection. Adrenergic agonists, phenylephrine (100 micrograms/kg), clonidine (5 micrograms/kg) and salbutamol (1 mg/kg) inhibited antral and pyloric activity. In decorticate rabbits the major effect of stimulation of the peripheral or the central end of the thoracic sympathetic trunk was inhibition; this was seen both with the spontaneous and vagally induced e.m.g. activity of the antrum and pylorus. Inhibition induced by stimulation of sympathetic efferents was abolished by beta-blocking agents and that induced by stimulation of the sympathetic afferents disappeared after alpha-adrenergic block. Significance of a dual control of the gastric motility by the sympathetic nerve was discussed.

Changes in regional blood flow and cardiodynamics evoked by electrical stimulation of the fastigial nucleus in the cat and their similarity to orthostatic reflexes.

1. Changes in regional blood flow and cardiodynamics were measured in anaesthetized paralysed cats during electrical stimulation of the rostral fastigial nucleus.2. Fastigial stimulation results in a graded, highly reproducible and stereotyped cardiovascular response characterized by (a) increased systolic, diastolic and mean arterial pressures without changes in central venous or occluded vein pressure, (b) decreased blood flow and increased vascular resistance in the axillary, renal, femoral and mesenteric arteries, increased flow without any change in vascular resistance in the common carotid artery, and increase in total peripheral resistance, (c) a small increase in heart rate and myocardial contractile force, decrease in calculated stroke volume, and no change in the cardiac output.3. Changes in regional arterial flow were abolished by transection of sympathetic nerves or blockade of alpha-adrenergic receptors by systemic administration of phentolamine.4. Changes in heart rate and myocardial contractility were abolished by stellate ganglionectomy or blockade of beta-adrenergic receptors by propranolol.5. No changes in pupillary diameter or retraction of the nictitating membrane were seen during fastigial stimulation with stimuli producing substantial changes in blood pressure.6. The fastigial pressor response represents a highly reproducible, stereotyped, graded, and differentiated pattern of activation of sympathetic preganglionic neurones.7. The pattern of cardiovascular effects of fastigial stimulation simulates the compensatory (orthostatic) reflex response to maintenance of an upright posture.8. Fastigial stimulation appears to excite the neural network subserving orthostatic reflexes.

I. Séglas and Heitz. Treatment of epilepsy by the Flechsig method. — Arch. neurology, № 56

Among the numerous methods of treatment of epilepsy, especially three have aroused attention over the past years: surgical intervention in the form of sympathetic nerve transection and pharmacological methods of Bekhterev and Fleksig.