Absence of gp130 in dopamine beta-hydroxylase-expressing neurons leads to autonomic imbalance and increased reperfusion arrhythmias.

Inflammatory cytokines that act through glycoprotein (gp)130 are elevated in the heart after myocardial infarction and in heart failure. These cytokines are potent regulators of neurotransmitter and neuropeptide production in sympathetic neurons but are also important for the survival of cardiac myocytes after damage to the heart. To examine the effect of gp130 cytokines on cardiac nerves, we used gp130(DBH-Cre/lox) mice, which have a selective deletion of the gp130 cytokine receptor in neurons expressing dopamine beta-hydroxylase (DBH). Basal sympathetic parameters, including norepinephrine (NE) content, tyrosine hydroxylase expression, NE transporter expression, and sympathetic innervation density, appeared normal in gp130(DBH-Cre/lox) compared with wild-type mice. Likewise, basal cardiovascular parameters measured under isoflurane anesthesia were similar in both genotypes, including mean arterial pressure, left ventricular peak systolic pressure, dP/dt(max), and dP/dt(min). However, pharmacological interventions revealed an autonomic imbalance in gp130(DBH-Cre/lox) mice that was correlated with an increased incidence of premature ventricular complexes after reperfusion. Stimulation of NE release with tyramine and infusion of the beta-agonist dobutamine revealed blunted adrenergic transmission that correlated with decreased beta-receptor expression in gp130(DBH-Cre/lox) hearts. Due to the developmental expression of the DBH-Cre transgene in parasympathetic ganglia, gp130 was eliminated. Cholinergic transmission was impaired in gp130(DBH-Cre/lox) hearts due to decreased parasympathetic drive, but tyrosine hydroxylase immunohistochemistry in the brain stem revealed that catecholaminergic nuclei appeared grossly normal. Thus, the apparently normal basal parameters in gp130(DBH-Cre/lox) mice mask an autonomic imbalance that includes alterations in sympathetic and parasympathetic transmission.

Neuronal nitric oxide mediates cerebral vasodilatation during acute hypertension.

Parasympathetic nerves from the pterygopalatine ganglia provide nitroxidergic innervation to forebrain cerebral blood vessels. Disruption of that innervation attenuates cerebral vasodilatation seen during acute hypertension as does systemic administration of a non-selective nitric oxide synthase (NOS) inhibitor. Although such studies suggest that nitric oxide (NO) released from parasympathetic nerves participates in vasodilatation of cerebral vessels during hypertension, that hypothesis has not been tested with selective local inhibition of neuronal NOS (nNOS). We tested that hypothesis through these studies performed in anesthetized rats instrumented for continuous measurement of blood pressure, heart rate and pial arterial diameter through a cranial window. We sought to determine if the nNOS inhibitor propyl-L-arginine delivered directly to the outer surface of a pial artery would (1) attenuate changes in pial arterial diameter during acute hypertension and (2) block nNOS-mediated dilator effects of N-methyl-D-aspartate (NMDA) delivered into the window but (3) not block vasodilatation elicited by acetylcholine (ACh) and mediated by endothelial NOS dilator. Without the nNOS inhibitor arterial diameter abruptly increased 70+/-15% when mean arterial pressure (MAP) reached 183+/-3 mm Hg while with nNOS inhibition diameter increased only 13+/-10% (p<0.05) even when MAP reached 191+/-4 mm Hg (p>0.05). The nNOS inhibitor significantly attenuated vasodilatation induced by NMDA but not ACh delivered into the window. Thus, local nNOS inhibition attenuates breakthrough from autoregulation during hypertension as does complete interruption of the parasympathetic innervation of cerebral vessels. These findings further support the hypothesis that NO released from parasympathetic fibers contributes to cerebral vasodilatation during acute hypertension.

Phenotype dependent differential effects of interleukin-1beta and amyloid-beta on viability and cholinergic phenotype of T17 neuroblastoma cells.

Amyloid-beta accumulation in brains of Alzheimer's disease (AD) victims is accompanied by glial inflammatory reactions and preferential loss of cholinergic neurons. Therefore, the aim of this study was to find out whether proinflamatory cytokine interleukin 1beta (IL1beta) modifies effects of amyloid-beta (Abeta) on viability and cholinergic phenotype of septum derived T17 cholinergic neuroblastoma cells. In nondifferentiated T17 cells (NC) Abeta(25-35) (1 microg/ml) caused no changes in choline acetyltransferase (ChAT) activity, acetylcholine (ACh) release, subcellular distribution of acetyl-CoA, but doubled content of trypan blue positive cells. IL1beta (10 ng/ml) increased ACh release (125%) but did not change other parameters of NC. In the presence of Abeta IL1beta also increased ChAT activity (47%), ACh release (100%) but had no effect on acetyl-CoA distribution and cell viability. Differentiation with retinoic acid and dibutyryl cyclic AMP caused over two-fold increase of ChAT activity and ACh content, four-fold increase of ACh release and about 50% decrease of acetyl-CoA level in the mitochondria. In differentiated cells (DC), Abeta decreased ChAT activity (31%), ACh release (47%) and content of acetyl-CoA (80%) in cell cytoplasmic compartment, whereas IL1beta elevated ChAT activity (54%) and ACh release (32%). IL1beta totally reversed Abeta-evoked inhibition of ChAT activity and ACh release and restored control level of cytoplasmic acetyl-CoA but increased fraction of nonviable cells to 25%. Thus, IL1beta could compensate Abeta-evoked cholinergic deficits through the restoration of adequate expression of ChAT and provision of acetyl-CoA to cytoplasmic compartment in cholinergic neurons that survive under such pathologic conditions. These data indicate that IL1beta possess independent cholinotrophic and cholinotoxic activities that may modify Abeta effects on cholinergic neurons.

P2X2 and P2Y1 immunofluorescence in rat neostriatal medium-spiny projection neurones and cholinergic interneurones is not linked to respective purinergic receptor function.

1. The presence of ionotropic P2X receptors, targets of ATP in fast synaptic transmission, as well as metabotropic P2Y receptors, known to activate K(+) currents in cultured neostriatal neurones, was investigated in medium-spiny neurones and cholinergic interneurones contained in neostriatal brain slices from 5-26-day-old rats. 2. In these cells, adenosine-5'-triphosphate (ATP) (100-1000 microm), 2-methylthioadenosine-5'-triphosphate (2MeSATP), alpha,beta-methyleneadenosine-5'-triphosphate (alpha,betameATP, 30-300 microm, each) and adenosine-5'-O-(3-thiotriphosphate (ATPgammaS) (100 microm) failed to evoke P2X receptor currents even when 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 0.1 microm), apyrase (10 U ml(-1)) or intracellular Cs(+) was used to prevent occluding effects of the ATP breakdown product adenosine, desensitisation of P2X receptors by endogenous ATP and an interference with the activation of K(+) channels, respectively. P2X receptor agonists were also ineffective in outside-out patches withdrawn from the brain slice tissue. Muscimol (10 microm) evoked GABA(A) receptor-mediated currents under all these conditions. 3. When used as a control, locus coeruleus neurones responded with P2X receptor-mediated currents to ATP (300 microm), 2MeSATP and alpha,betameATP (100 microm, each). 4. ATP and adenosine-5'-diphosphate (ADP) (100 microm, each) did not activate K(+) currents in the neostriatal neurones. 5. Despite the observed lack of function, P2X(2) and P2Y(1) immunofluorescence was found in roughly 50% of the medium-spiny neurones and cholinergic interneurones. 6. A role of ATP in synaptic transmission to striatal medium-spiny neurones and cholinergic interneurones appears unlikely, however, the otherwise silent P2X and P2Y receptors may gain functionality under certain yet unknown conditions.

Effects of haloperidol on cholinergic striatal interneurons: relationship to oral dyskinesias.

In a subset of rats, typical antipsychotic drugs (tAPD) produce oral dyskinesias called vacuous chewing movements (VCMs) that resemble tardive dyskinesia (TD), a behavioral side effect seen in a subset of people following tAPD treatment. Morphological changes within the striatum following tAPD have been correlated to VCMs in animal models. The cholinergic system has been implicated in expression of TD. To test the hypothesis that the striatal cholinergic system is perturbed after haloperidol treatment, rats were administered haloperidol for three weeks and tested for VCMs; the striata were then processed for the immunocytochemical localization of choline-acetyltransferase (ChAT). Neuronal density measures of ChAT-labeled neurons showed a 22% decrease in haloperidol-treated versus controls rats and a 37% reduction in the lateral portion of the striatum only in rats with VCMs. These findings further support evidence of the possible involvement of the cholinergic system and the ventrolateral striatum in VCMs, and possibly TD.

Environment-spatial conditional learning in rats with selective lesions of medial septal cholinergic neurons.

Cholinergic medial septal neurons may regulate several aspects of hippocampal function, including place field stability and spatial working memory. Monkeys with damage to septal cholinergic neurons are impaired in visual-spatial conditional learning tasks; however, this candidate function of septal cholinergic neurons has not been studied extensively in the rat. In the present study, rats with selective lesions of cholinergic neurons in the medial septum and vertical limb of the diagonal band of Broca (MS/VDB), made with 192 IgG-saporin, were tested on a conditional associative learning task. In this task, which we term "environment-spatial" conditional learning, the correct location of a spatial response depended on the array of local environmental cues. MS/VDB-lesioned rats were impaired when the two parts of the conditional problem were presented concurrently, but not when one environment had been learned before the full conditional problem was presented. Our findings suggest that cholinergic MS/VDB neurons participate in some aspects of conditional associative learning in rats. They may also shed light on the involvement of cholinergic projections to the hippocampus in modulating and remodeling hippocampal spatial representations.

Quantitative immunohistochemical investigation of the intrinsic vasodilator innervation of the guinea pig lingual artery.

The vasculature of the guinea pig tongue is supplied by parasympathetic vasodilator nerve fibres of intrinsic origin. Here, we investigated first to what extent neuropeptides and the synthesizing enzymes of NO, CO and acetylcholine are contained and colocalized within periarterial lingual vasodilator axons of intrinsic origin. Then it was determined whether perivascular innervation by these fibre types changes with vascular diameter, in particular in comparison with the sensory substance P (SP)-positive and sympathetic noradrenergic vascular innervation. To this end, single, double and triple labelling histochemical techniques were performed on control tongues and tongues kept in short-term organotypic culture to induce degeneration of extrinsically originating nerve fibres. Cell bodies of intrinsic microganglia and their periarterial axons contained, simultaneously, NO synthase, vasoactive intestinal peptide and the acetylcholine-synthesizing enzyme choline acetyltransferase. Additionally, neuropeptide Y (NPY) was observed in a small percentage (12%) of neurons that increased to 39% after 36 h of organotypic culture. The CO synthesizing enzyme heme oxygenase-2 was detected only in perikarya but not in periarterial axons. Intrinsic vasodilator fibres were invariably present at arteries down to a luminal diameter of 150 microm, and reached 65% of section profiles of smallest arterioles, while noradrenergic and substance P-positive axons reached 80% of arteriolar profiles. These findings show that the intrinsic lingual vasodilator innervation of the guinea pig is far extending although slightly less developed than that by sensory and sympathetic axons, and differs both in this aspect and in patterns of colocalization from that reported for other organs, e.g. lung and pelvic organs.

Selective immunolesions of CH4 cholinergic neurons do not disrupt spatial memory in rats.

Adult male Long-Evans rats were subjected to bilateral lesions of the cholinergic neurons in the nucleus basalis magnocellularis (NBM) by injection of 0.2 or 0.4 microg 192-IgG-saporin in 0.4 microl phosphate-buffered saline. Control rats received an equivalent amount of phosphate-buffered saline. Starting 2 weeks after surgery, all rats were tested for locomotor activity in their home cage, beam-walking performance, T-maze alternation rates (working memory), reference and working memory performance in a water-maze task, and memory capabilities in the eight-arm radial maze task using uninterrupted and interrupted (delay of 2 min, 2 h and 6 h after four arms had been visited) testing procedures. Histochemical analysis showed a significant decrease of acetylcholinesterase (AChE)-positive reaction products (30-66%) in various cortical regions at the 0.2-microg dose. At the dose of 0.4 microg, there was an additional, although weak, damage to the hippocampus (17-30%) and the cingulate cortex (34%). The behavioral results showed only minor impairments in spatial memory tasks, and only during initial phases of the tests (reference memory in the water maze, working memory in the radial maze). The behavioral effects of the dramatic cholinergic lesions do not support the idea of a substantial implication of cholinergic projections from the NBM to the cortex in the memory processes assessed in this study, but they remain congruent with an involvement of these projections in attentional functions.

Parasympathetic innervation of the meibomian glands in rats.

PURPOSE: To determine the location of parasympathetic neurons that innervate the meibomian glands in rats. METHODS: The B subunit of cholera toxin (CTB), fast blue, and a retrograde transneuronal tracer, the Bartha strain of pseudorabies virus (PRV-Ba), were injected into the upper eyelids of adult Sprague-Dawley rats after sectioning the ipsilateral branches of the facial nerve and resecting the superior cervical ganglia. Brains and orbital tissues were processed for the immunohistochemical detection of PRV-Ba and CTB. In selected cases, series of brain sections were double labeled for PRV-Ba and tyrosine hydroxylase to determine the relationship between the A5 noradrenergic cell group and superior salivatory nucleus, or for PRV-Ba and choline acetyltransferase to establish the neurochemical phenotype of parasympathetic preganglionic neurons. RESULTS: Labeled ganglionic cells were diffusely distributed within the ipsilateral pterygopalatine ganglion (PPG) and along the more proximal portions of the greater petrosal nerve (GPN). Labeled preganglionic neurons were cholinergic and were located immediately dorsolateral to the rostral-most portion of the facial nucleus and caudal superior olive, where they intermingled with A5 noradrenergic cells. CONCLUSIONS: The meibomian glands and other structures within the lid margin are subject to parasympathetic regulation by ganglion cells diffusely distributed within the PPG and along more proximal portions of the GPN. Cholinergic parasympathetic preganglionic neurons that project to meibomian gland-innervating ganglion cells are located immediately lateral, dorsal, and rostral to the facial motor nucleus in the region commonly referred to as the superior salivatory nucleus.

A protein phosphatase is involved in the cholinergic suppression of the Ca(2+)-activated K(+) current sI(AHP) in hippocampal pyramidal neurons.

The slow calcium-activated potassium current sI(AHP) underlies spike-frequency adaptation and has a substantial impact on the excitability of hippocampal CA1 pyramidal neurons. Among other neuromodulatory substances, sI(AHP) is modulated by acetylcholine acting via muscarinic receptors. The second-messenger systems mediating the suppression of sI(AHP) by muscarinic agonists are largely unknown. Both protein kinase C and A do not seem to be involved, whereas calcium calmodulin kinase II has been shown to take part in the muscarinic action on sI(AHP). We re-examined the mechanism of action of muscarinic agonists on sI(AHP) combining whole-cell recordings with the use of specific inhibitors or activators of putative constituents of the muscarinic pathway. Our results suggest that activation of muscarinic receptors reduces sI(AHP) in a G-protein-mediated and phospholipase C-independent manner. Furthermore, we obtained evidence for the involvement of the cGMP-cGK pathway and of a protein phosphatase in the cholinergic suppression of sI(AHP), whereas release of Ca(2+) from IP(3)-sensitive stores seems to be relevant neither for maintenance nor for modulation of sI(AHP).

Induction of choline acetyltransferase activity in cholinergic neurons by stolonidiol: structure-activity relationship.

The effect of stolonidiol (1), a bioactive marine diterpenoid from the Japanese soft coral Clavularia sp., on choline acetyltransferase (ChAT) activity was examined using cultured cholinergic neurons. Stolonidiol (1) showed potent ChAT inducible activity in primary cultured basal forebrain cells and clonal septal SN49 cells, suggesting that it may act as a potent neurotrophic factor-like agent on the cholinergic nervous system. Further expansion of the structure-activity relationship to include stolonidiol (1) and its derivatives demonstrated that the exo-methylene group and the epoxide group are essential for ChAT-inducing activity. Stolonidiol (1) showed the highest activity among the test samples.

Distribution, chemical coding and origin of nitric oxide synthase-containing nerve fibres in the guinea pig nasal mucosa.

The distribution, chemical coding and origin of nitric oxide synthase (NOS)-containing nerve fibres in the respiratory mucosa of the nasal septum of the guinea pig were examined using nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry and immunohistochemistry. A rich supply of NADPH-d-positive nerve fibres was observed around blood vessels and in nasal glands where nerve fibres frequently penetrated into the epithelia of acini and intralobular ducts. NADPH-d reactivity was also found in the nerve fibres located under or within the respiratory epithelium. Combined immunofluorescence and histochemical staining of the same preparation demonstrated virtually complete overlapping of NOS immunoreactivity and NADPH-d reactivity in nerve fibres, indicating that NADPH-d can be used as a marker for NOS-containing neurons. Double-labelling using antibodies to vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) revealed that NADPH-d-positive nerve fibres frequently contained VIP or NPY, but not CGRP. Pterygopalatine ganglionectomy significantly reduced the number of NADPH-d-positive nerve fibres innervating the respiratory epithelium as well as blood vessels and nasal glands. Neither superior cervical ganglionectomy nor sensory denervation by capsaicin treatment affected the distribution of NADPH-d-positive fibres. These results indicate that NOS-containing nerve fibres innervating the respiratory epithelium as well as blood vessels and nasal glands in the guinea pig originate mainly from the pterygopalatine ganglion, and suggest that NO may play a significant role as a neurotransmitter and/or neuromodulator in the control of the respiratory epithelium as well as vasculature and nasal glands.

Alterations in spinal cord Fos protein expression induced by bladder stimulation following cystitis.

These studies examined Fos protein expression in spinal cord neurons synaptically activated by stimulation of bladder afferent pathways after cyclophosphamide (CYP)-induced bladder inflammation. In urethan-anesthetized Wistar rats with cystitis, intravesical saline distension significantly (P

Two distinct populations of cholinergic neurons in the septum of raccoon (Procyon lotor): evidence for a separate subset in the lateral septum.

The present study focused on cholinergic neurons in the lateral septal region of the raccoon detected by choline acetyltransferase (ChAT)-immunostaining. For comparison of the cholinergic neurons of the medial and lateral septal nuclei, soma sizes were measured, and several antibodies were applied that differentially characterize these cells in several species: low-affinity neurotrophin receptor p75 (p75(NTR)), calbindin-D(28k) (CALB), and constitutive nitric oxide synthase (cNOS). To compare the basic organization of the raccoon septum with that in other mammals, parvalbumin (PARV) immunocytochemistry and Wisteria floribunda-agglutinin (WFA) lectin histochemistry also were used in double-staining experiments. The ChAT-immunoreactive neurons of the rostral lateral septum are arranged in laminae. Accumulations of cholinergic varicosities, often clearly ensheathing noncholinergic neurons, occupy small territories of the rostral septum. Such regions become larger in the caudal septum. They are assumed to correspond to the septohippocampal and septofimbrial nuclei of the rat. In contrast to the large medial septal cholinergic neurons of the raccoon that contain p75(NTR), CALB, and cNOS, the cholinergic neurons of the lateral septum are smaller and do not express these markers. A further peculiarity is that the region of the lateral septum that contains cholinergic neurons corresponds to WFA-labelled extracellular matrix zones that contain chondroitin sulfate proteoglycans. In addition to clustered thread- or ring-like accumulations of the WFA, sparsely labelled perineuronal nets surround the lateral septal cholinergic neurons. Similar to other species that have been investigated, perineuronal nets are completely absent around cholinergic cells of the medial septum. The PARV-containing neurons of this region, however, are enwrapped by perineuronal nets as they are in the rat. Within the medial septum, the PARV-containing neurons are restricted to ventral bilateral territories that are devoid of cholinergic cells. In this respect, they differ from the more vertically arranged PARV-containing medial septal cells in rodents and primates. Apart from striking differences in numbers and distribution patterns, the raccoon lateral septal cholinergic neurons resemble those detected by Kimura et al. (Brain Res [1990] 533:165-170) in the ventrolateral septal region of rat and monkey. Their participation in the functions of the lateral septum remains to be elucidated.

The origin of catecholaminergic nerve fibers in the subdiaphragmatic vagus nerve of rat.

It is known that the vagus nerve contains catecholaminergic fibers. However, the origin of these fibers has not been systematically examined. In this study, we addressed this issue using retrograde tracing from the subdiaphragmatic vagus nerve combined with immunocytochemistry. The cervical and thoracic sympathetic trunk ganglia, the nodose ganglia and the dorsal motor nucleus of the vagus nerve were examined following injection of Fluoro-Gold or cholera toxin horseradish peroxidase conjugate into the trunks of the subdiaphragmatic vagus nerve of rats. Numerous retrogradely labeled neurons were seen in the nodose ganglion and the dorsal motor nucleus of the vagus nerve. Very few labeled neurons were found in the sympathetic ganglia (less than 0.06% of the neurons in either superior cervical ganglion or cervicothoracic ganglion were retrogradely labeled). Double labeling with immunofluoresence for catecholamine synthesizing enzymes revealed that: (1) 92% of all Fluoro-Gold retrogradely labeled tyrosine hydroxylase immunoreactive neurons were found in parasympathetic sources (75% in the dorsal motor nucleus of the vagus nerve and 17% in the nodose ganglia), and only 8% in the cervicothoracic sympathetic ganglia; (2) 12% of the retrogradely labeled catecholaminergic neurons in the dorsal motor nucleus of the vagus nerve were also dopamine-beta-hydroxylase immunopositive neurons; (3) 70% of the retrogradely labeled neurons in the sympathetic ganglia were tyrosine hydroxylase immunopositive and 54% of these catecholaminergic neurons contained dopamine-beta-hydroxylase, while 30% of the retrogradely labeled neurons were non-catecholaminergic neurons. These results indicate that catecholaminergic fibers in the abdominal vagus nerve are primarily dopaminergic and of parasympathetic origin, and that only an extremely small number of these fibers, mostly noradrenergic in nature, arise from postganglionic sympathetic neurons.

NO synthase in cholinergic nerves and NO-induced relaxation in the rat isolated corpus cavernosum.

1. In the rat corpus cavernosum (CC), the distribution of immunoreactivity for neuronal and endothelial NO synthase (nNOS and eNOS), and the pattern of NOS-immunoreactive (-IR) nerves in relation to some other nerve populations, were investigated. Cholinergic nerves were specifically immunolabelled with antibodies to the vesicular acetylcholine transporter protein (VAChT). 2. In the smooth muscle septa surrounding the cavernous spaces, and around the central and helicine arteries, the numbers of PGP- and tyrosine hydroxylase (TH)-IR terminals were large, whereas neuropeptide Y (NPY)-, VAChT-, nNOS-, and vasoactive intestinal polypeptide (VIP)-IR terminals were found in few to moderate numbers. 3. Double immunolabelling revealed that VAChT- and nNOS-IR terminals, VAChT- and VIP-IR terminals, nNOS-IR and VIP-IR terminals, and TH- and NPY-IR terminals showed coinciding profiles, and co-existence was verified by confocal laser scanning microscopy. TH immunoreactivity was not found in VAChT-, nNOS-, or VIP-IR nerve fibres or terminals. 4. An isolated strip preparation of the rat CC was developed, and characterized. In this preparation, cumulative addition of NO to noradrenaline (NA)-contracted strips, produced concentration-dependent, rapid, and almost complete relaxations. Electrical field stimulation of endothelin-1-contracted preparations produced frequency-dependent responses: a contractile twitch followed by a fast relaxant response. After cessation of stimulation, there was a slow relaxant phase. Inhibition of NO synthesis, or blockade of guanylate cyclase, abolished the first relaxant phase, whereas the second relaxation was unaffected. 5. The results suggest that in the rat CC, nNOS, VAChT- and VIP-immunoreactivities can be found in the same parasympathetic cholinergic neurons. Inhibitory neurotransmission involves activation of the NO-system, and the release of other, as yet unknown, transmitters.

Evidence suggesting that lateral parabrachial nucleus is responsible for enhanced medullary cholinergic activity in hypertension.

Cholinergic activities in the rostral ventrolateral medulla are enhanced in hypertensive animals, and enhanced cholinergic activity contributes to hypertension. Neurons in the lateral parabrachial nucleus and baroreceptors are suggested to be involved in mediation of acetylcholine release in the rostral ventrolateral medulla. To investigate the hypothesis that the lateral parabrachial nucleus is involved in the increased medullary cholinergic activity in hypertensive rats, we measured choline acetyltransferase activity in the rostral ventrolateral medulla, and examined effects of electrolytic lesioning of the lateral parabrachial nucleus in deoxycorticosterone acetate-salt hypertensive rats. We found that choline acetyl-transferase activity in the medullary region was increased in deoxycorticosterone acetate-salt hypertensive rats. Unilateral lesioning of the lateral parabrachial nucleus abolished the increase in choline acetyltransferase activity in the lesioned side of the medullary region of hypertensive rats, whereas such activity in the medullary region of control rats was unaffected by lesioning. Bilateral lesioning of the lateral parabrachial nucleus inhibited the development of hypertension in hypertensive rats. In contrast, baroreceptor denervation did not inhibit the increase in choline acetyltransferase activity in the medullary region of hypertensive rats. These results are compatible with the hypothesis that the lateral parabrachial nucleus area is involved in mediation of increased medullary cholinergic activity and thus plays a role in the development of hypertension.

The vagal origin of preganglionic fibers containing nitric oxide synthase in the guinea-pig heart.

The origin of nerve fibers projecting to the guinea pig heart that contain nitric oxide synthase (NOS) were studied by unilateral cervical vagotomy. Three kinds of NOS-immunoreactive (NOS-ir) nerve fibers are distributed in the control guinea pig heart: the sparse network covering the right atrium, the basket-like endings around intracardiac neuronal cell bodies in the small ganglia located in the left atrium and the interatrial septum, and the axons situated in the septal region. The sparse network in the right atrium did not change after vagotomy of right or left side. In the whole mount preparations of right atrium, we often traced labeled axons from the somata to join the network covering the right atrium. Therefore, most of this network of labeled fibers must be of intrinsic origin. Because the basket-like endings around neuronal cell bodies in the ganglia in the left atrium and the septum disappeared completely after vagotomy of left side, we conclude that they are parasympathetic preganglionic fibers originating from the left vagus nerve. NOS-ir cell bodies and the positive fibers in the atrioventricular nodal region survived after vagotomy. All of such nerve fibers were unmyelinated axons. Therefore, they seem to be the postganglionic fibers arising from the ganglia located in the left atrium or the septum.

The sympathetic skin response in peripheral autonomic failure--evaluation in pure failure, pure cholinergic dysautonomia and dopamine-beta-hydroxylase deficiency.

The sympathetic skin response (SSR) detects changes in the electrical potential in the skin in response to physiological and electrical stimuli and, therefore, may indicate the integrity of sympathetic cholinergic neural pathways to sweat glands. This has been evaluated in 21 patients with three forms of peripheral autonomic failure. Of these, 15 had pure autonomic failure (PAF) without additional neurological features; investigations indicated both sympathetic and parasympathetic failure. Four patients had pure cholinergic dysautonomia (PCD), with clinical and laboratory features indicating only cholinergic failure. Two siblings had dopamine-beta-hydroxylase (DBH) deficiency with only sympathetic adrenergic failure. None was on drugs affecting cholinergic function. Ten normal individuals were aged-matched with PAF patients and studied as controls. The SSR was recorded from the palmar hand and plantar foot surfaces, using previously described techniques, in response to physiological (auditory, cough and inspiratory gasp) and electrical stimuli. Nerve conduction studies excluded an associated motor or sensory neuropathy. The SSR was present in all normal individuals, and in both patients with DBH deficiency who had preserved cholinergic and sudomotor function, It was absent in all 15 PAF and all four PCD patients with impaired cholinergic function. Therefore, we conclude that the SSR reflected sympathetic cholinergic function in these three different groups with peripheral autonomic failure.