Cardiac autonomic neuropathy is a frequent complication of diabetes and often presents as impaired cholinergic regulation of heart rate. Some have assumed that diabetics have degeneration of cardiac cholinergic nerves, but basic knowledge on this topic is lacking. Accordingly, our goal was to evaluate the structure and function of cardiac cholinergic neurons and nerves in C57BL/6 mice with streptozotocin-induced diabetes. Electrocardiograms were obtained weekly from conscious control and diabetic mice for 16. weeks. Resting heart rate decreased in diabetic mice, but intrinsic heart rate was unchanged. Power spectral analysis of electrocardiograms revealed decreased high frequency and increased low frequency power in diabetic mice, suggesting a relative reduction of parasympathetic tone. Negative chronotropic responses to right vagal nerve stimulation were blunted in 16-week diabetic mice, but postjunctional sensitivity of isolated atria to muscarinic agonists was unchanged. Immunohistochemical analysis of hearts from diabetic and control mice showed no difference in abundance of cholinergic neurons, but cholinergic nerve density was increased at the sinoatrial node of diabetic mice (16. weeks: 14.9 ± 1.2% area for diabetics versus 8.9 ± 0.8% area for control, P< 0.01). We conclude that disruption of cholinergic function in diabetic mice cannot be attributed to a loss of cardiac cholinergic neurons and nerve fibers or altered cholinergic sensitivity of the atria. Instead, decreased responses to vagal stimulation might be caused by a defect of preganglionic cholinergic neurons and/or ganglionic neurotransmission. The increased density of cholinergic nerves observed at the sinoatrial node of diabetic mice might be a compensatory response.

Baroreflex sensitivity is impaired by diabetes mellitus. Previously, we found that diabetes induces a deficit of central mediation of baroreflex-mediated bradycardia. In this study, we assessed whether diabetes induces degeneration of the nucleus ambiguus (NA) and reduces heart rate (HR) responses to l-Glutamate (L-Glu) microinjection into the NA. FVB control and OVE26 diabetic mice (5-6 months) were anesthetized. Different doses of L-Glu (0.1-5 mM/l, 20 nl) were delivered into the left NA using a multi-channel injector. In other animals, the left vagus was electrically stimulated at 1-40 Hz (1 ms, 0.5 mA, 20 s). HR and mean arterial blood pressure (MAP) responses to L-Glu microinjections into the NA and to the electrical stimulation of the vagus were measured. The NA region was defined by tracer TMR-D injection into the ipsilateral nodose ganglion to retrogradely label vagal motoneurons in the NA. Brainstem slices at - 600, - 300, 0, + 300, and + 600 μm relative to the obex were processed using Nissl staining and the number of NA motoneurons was counted. Compared with FVB control, we found in OVE26 mice that: 1) HR responses to L-Glu injection into the NA at doses of 0.2-0.4 (mM/l, 20 nl) were attenuated (p < 0.05), but MAP responses were unchanged (p > 0.05). 2) HR responses to vagal stimulation were increased (p < 0.05). 3) The total number of NA (left and right) motoneurons was reduced (p < 0.05). Taken together, we concluded that diabetes reduces NA control of HR and induces degeneration of NA motoneurons. Degeneration of NA cardiac motoneurons may contribute to impairment of reflex-bradycardia in OVE26 diabetic mice.

The presence of vasoactive intestinal polypeptide (VIP) has been analyzed in fibers and neurons within the guinea pig intrinsic cardiac ganglia and in fibers innervating cardiac tissues. In whole-mount preparations, VIP-immunoreactive (IR) fibers were present in about 70% of the cardiac ganglia. VIP was co-localized with neuronal nitric oxide synthase (nNOS) in fibers innervating the intrinsic ganglia but was not present in fibers immunoreactive for pituitary adenylate cyclase-activating polypeptide, choline acetyltransferase (ChAT), tyrosine hydroxylase, or substance P. A small number of the intrinsic ChAT-IR cardiac ganglia neurons (approximately 3%) exhibited VIP immunoreactivity. These few VIP-IR cardiac neurons also exhibited nNOS immunoreactivity. After explant culture for 72 h, the intraganglionic VIP-IR fibers degenerated, indicating that they were axons of neurons located outside the heart. In cardiac tissue sections, VIP-IR fibers were present primarily in the atria and in perivascular connective tissue, with the overall abundance being low. VIP-IR fibers were notably sparse in the sinus node and conducting system and generally absent in the ventricular myocardium. Virtually all VIP-IR fibers in tissue sections exhibited immunoreactivity to nNOS. A few VIP-IR fibers, primarily those located within the atrial myocardium, were immunoreactive for both nNOS and ChAT indicating they were derived from intrinsic cardiac neurons. We suggest that, in the guinea pig, the majority of intraganglionic and cardiac tissue VTP-IR fibers originate outside of the heart. These extrinsic VIP-IR fibers are also immunoreactive for nNOS and therefore most likely are a component of the afferent fibers derived from the vagal sensory ganglia.

The nucleus of the solitary tract (NTS) receives viscerosensory information from the vagus nerve to regulate diverse homeostatic reflex functions. The NTS projects to a wide network of other brain regions, including the paraventricular nucleus of the hypothalamus (PVN). Here we examined the synaptic characteristics of primary afferent pathways to PVN-projecting NTS neurons in rat brainstem slices. Expression of the Transient Receptor Potential Vanilloid receptor (TRPV1+ ) distinguishes C-fiber afferents within the solitary tract (ST) from A-fibers (TRPV1-). We used resiniferatoxin (RTX), a TRPV1 agonist, to differentiate the two. The variability in the latency (jitter) of evoked excitatory postsynaptic currents (ST-EPSCs) distinguished monosynaptic from polysynaptic ST-EPSCs. Rhodamine injected into PVN was retrogradely transported to identify PVN-projecting NTS neurons within brainstem slices. Graded shocks to the ST elicited all-or-none EPSCs in rhodamine-positive NTS neurons with latencies that had either low jitter (<200 µs – monosynaptic), high jitter (>200 µs - polysynaptic inputs) or both. RTX blocked ST-evoked TRPV1 + EPSCs whether mono- or polysynaptic. Most PVN-projecting NTS neurons (17/21 neurons) had at least one input polysynaptically connected to the ST. Compared to unlabeled NTS neurons, PVN-projecting NTS neurons were more likely to receive indirect inputs and be higher order. Surprisingly, sEPSC rates for PVN-projecting neurons were double that of unlabeled NTS neurons. The ST synaptic responses for PVN-projecting NTS neurons were either all TRPV1+ or all TRPV1-, including neurons that received both direct and indirect inputs. Overall, PVN-projecting NTS neurons received direct and indirect vagal afferent information with strict segregation regarding TRPV1 expression.

Vagus nerve stimulation (VNS) currently treats patients with drug-resistant epilepsy, depression, and heart failure. The mild intensities used in chronic VNS suggest that primary visceral afferents and central nervous system activation are involved. Here, we measured the activity of neurons in the nucleus of the solitary tract (NTS) in anesthetized rats using clinically styled VNS. Our chief findings indicate that VNS at threshold bradycardic intensity activated NTS neuron discharge in one-third of NTS neurons. This VNS directly activated only myelinated vagal afferents projecting to second-order NTS neurons. Most VNS-induced activity in NTS, however, was unsynchronized to vagal stimuli. Thus, VNS activated unsynchronized activity in NTS neurons that were second order to vagal afferent C-fibers as well as higher-order NTS neurons only polysynaptically activated by the vagus. Overall, cardiovascular-sensitive and -insen-sitive NTS neurons were similarly activated by VNS: 3/4 neurons with monosynaptic vagal A-fiber afferents, 6/42 neurons with monosynaptic vagal C-fiber afferents, and 16/21 polysynaptic NTS neurons. Provocatively, vagal A-fibers indirectly activated C-fiber neurons during VNS. Elevated spontaneous spiking was quantitatively much higher than synchronized activity and extended well into the periods of nonstimulation. Surprisingly, many polysynaptic NTS neurons responded to half the bradycardic intensity used in clinical studies, indicating that a subset of myelinated vagal afferents is sufficient to evoke VNS indirect activation. Our study uncovered a myelinated vagal afferent drive that indirectly activates NTS neurons and thus central pathways beyond NTS and support reconsideration of brain contributions of vagal afferents underpinning of therapeutic impacts. NEW & NOTEWORTHY Acute vagus nerve stimulation elevated activity in neurons located in the medial nucleus of the solitary tract. Such stimuli directly activated only myelinated vagal afferents but indirectly activated a subpopulation of second- and higher-order neurons, suggesting that afferent mechanisms and central neuron activation may be responsible for vagus nerve stimulation efficacy.

Transcutaneous auricular vagal nerve stimulation (taVNS) is a non-invasive method of activating axons in the auricular branch of the vagus nerve through the concha of the outer ear. taVNS is under investigation as an alternative treatment option for a wide range of disorders. Vagal afferent fibers terminate in the nucleus of the solitary tract (NTS) where information is processed and relayed to higher brain regions influencing sympathetic and parasympathetic systems. Due to extensive neuronal connections, it is likely that taVNS could serve as a treatment option for many disorders, specifically cardiac, migraine, and gastric motility disorders. Human fMRI studies have indicated that taVNS elicits neuronal responses within NTS and spinal trigeminal nucleus (Sp5c). Studies have indicated that caudal NTS (cNTS) has substantial connections with the cardiac system, rostral NTS (rNTS) is relevant for gastric motility, and Sp5c is likely involved in migraine disorders due to meningeal connections. Aberrant neuronal signaling is likely responsible for the development of these disorders, and taVNS has the potential to modulate neuronal activity to reestablish homeostatic signaling. In this study, electrophysiological methods were used to interrogate neuronal activity of 50-70 neurons within cNTS, rNTS, and Sp5c following taVNS. A high-impedance tungsten electrode was placed stereotaxically in 15 male Sprague-Dawley rats anesthetized with chloralose. Changes in neuronal firing rates were investigated during and immediately following taVNS by comparing changes in neuronal activity to baseline levels using the software Spike 2 v9.14. Neurons were classified as negative responders if activity decreased more than 20%, positive responders if activity increased more than 20%, or non-responders if activity changes were less than 20%. Six different taVNS parameters were investigated using three frequencies (20, 100, 250Hz) at two intensity levels (0.5, 1.0mA). Data from this study suggest that taVNS can modulate neuronal activity in a frequency and intensity-dependent manner. The greatest positive activation for all 3 brain regions occurred at 20Hz, 1.0mA stimulation where an average of 46% ± 9% neurons showed increased firing compared to 29% ± 2% positive responders for other paradigms. The greatest negative activation for all 3 regions occurred at 100Hz, regardless of intensity, where an average of 33% ± 1% neurons showed reduced firing compared to 15% ± 2% negative responders for remaining paradigms. Based on what is known about cardiac, migraine, and gastric motility disorders, it is likely that taVNS can be used to modulate activity in NTS and Sp5c to provide beneficial treatment options to patients. Specifically, using paradigms yielding decreased activity in Sp5c could improve migraine symptoms, and paradigms increasing activity in cNTS and rNTS could improve cardiac and gastric motility disorders, respectively.

Endomorphin 1 (10, 30, 100 nmol/kg) administered intravenously (i.v.) to urethane-anesthetized rats consistently and dose-dependently lowered heart rate (HR) and mean arterial pressure (MAP); the decrease in blood pressure recovered faster as compared to the HR. The effects of endomorphin 2 were qualitatively similar. Naloxone (2 mg/kg, i.v.) completely antagonized the bradycardia and hypotension caused by endomorphin 1. Pretreatment of the rats with atropine methylnitrate, atropine sulfate (2 mg/kg, i.v.) or bilateral vagotomy nearly abolished the bradycardia and attenuated the hypotensive effect of endomorphin 1. Our studies suggest that the bradycardia effect following systemic administration of the new opioid peptide may be explained by activation of vagal afferents and the hypotensive effect may be secondary to a reduction of cardiac output and/or a direct vasodilation.

No description available.

This study examined the linkages between marital harmony and conflict and infants' emotional and physiological regulation abilities and developmental status at six- and nine-months of age. Participants included 93 first-time mothers and their infants (43 males, 50 females) from a Mountain West community. Mothers were asked to complete a battery of questionnaires, including a demographic measure and Braiker and Kelly's (1979) marital quality questionnaire. The revised Bayley Scales of Infant Development (BSID II) and Behavior Rating Scales (BRS) 2nd Edition were administered at six- and nine-months to measure infants' mental and motor development status and emotional regulation abilities. Infants' heart rate was also measured at six- and nine-months to measure their physiological regulation abilities. While correlations were found between high levels of marital conflict and infants' emotional regulation abilities at six-months, these correlations were not found at nine-months. However, this study was able to tease apart the direction of affect between marital conflict and infants' emotional and physiological regulation. Based on previous literature, it was hypothesized that marital conflict at six-months would predict infants' regulatory abilities at nine-months. However, the results from this study suggest that infant variables at six-months predict marital quality at nine-months. Specifically, infants' low emotional and physiological regulation abilities at six-months predicts higher levels of marital conflict at nine-months. Overall, these findings present a new perspective and offer new insights into the relationship between marital conflict and infants' regulation abilities. These findings have important implications for understanding the impact that infants' poorer regulation abilities can have on a marriage. Additional research is needed to further investigate the long-term consequences of infants' regulatory abilities on marital functioning and vice versa.

Seit drei Jahrzehnten eröffnet die elektrische Stimulation des Nervus vagus (N. X) neue Möglichkeiten in der Therapie chronischer Erkrankungen wie Epilepsie oder rheumatoider Arthritis. Hierfür erfolgt die chirurgische Implantation einer Elektrode am cervicalen Anteil des N. X. Therapeutische Nebenwirkungen treten bei zwei von drei Patienten auf (Giordano et al. 2017), während bei einem Viertel der behandelten Patienten kein therapeutischer Nutzen messbar ist (Englot et al. 2011). Ultraschall wird zur Beurteilung der Morphologie und zur Messung der Nervenquerschnittsflächen des N. X eingesetzt. Bis heute ist jedoch unklar, wie präzise der Ultraschall den N. X im Kontext der Stimulationstherapie beschreiben kann. Ziel dieser Arbeit war es daher, die im Ultraschall ermittelte Nervenquerschnittsfläche des N. X kritisch im Hinblick auf ihre Bedeutung für die klinische Stimulationstherapie zu beurteilen. Die Abformung mit Epineurium des N. X mit zeichnungsscharfen dentalen Abformmaterialien ermittelt Messwerte, die der Nervenquerschnittsfläche im klinischen Kontext am ehesten entsprechen (Reid 1990; Spuck et al. 2010; Giordano et al. 2017; González et al. 2019; Patil et al. 2001). Bei 12 nativen Körperspendern wurde deshalb die Nervenquerschnittsfläche des N. X im Ultraschall und in der Histologie dargestellt und mit Messwerten aus einer manuellen Abformung des Nervs verglichen. Die Kombination dreier Methoden zur Ermittlung der Nervenquerschnittsfläche des N. X stellt einen neuen und bisher nicht praktizierten Untersuchungsansatz dar und ist Alleinstellungsmerkmal dieser Arbeit. Die Nervenquerschnittsfläche des N. X im Ultraschall war kleiner als in der Abformung mit Epineurium und in der Histologie (1,5±0,4 vs. 3,1±0,9 vs. 2,3±0,7 mm2). Die Berücksichtigung des Epineuriums ergab signifikante Unterschiede in der gemessenen Nervenquerschnittsfläche. Die Messung der Nervenquerschnittsfläche des N. X im Ultraschall führte zu einer systematischen Unterschätzung, während die Ultraschallmessung mit Epineurium zu einer systematischen Überschätzung der Querschnittsfläche im Vergleich zur Messung in der Abformung mit Epineurium führte. Der Ultraschall ist somit wahrscheinlich keine geeignete Messmethode zur präoperativen Einschätzung der Nervenquerschnittsfläche des N. X. In der klinischen Praxis könnte durch eine zu kleine Elektrode die Gefäßversorgung des N. X unterbrochen und die folgende Hypoxie mit partialer axonaler Degeneration die häufig auftretenden Nebenwirkungen erklären. Stimmbandlähmungen wurden in diesem Kontext bereits als Folge der resultierenden Hypoxie beschrieben (Robinson und Winston 2015; Révész et al. 2016). Eine zu große Elektrode könnte in einer insuffizienten Überleitung elektrischer Impulse von der Elektrode auf den Nerv resultieren und erklären, weshalb die Stimulationstherapie bei einigen Patienten keine messbare Wirkung entfaltet. Die Magnetresonanztomographie (MRT) bildet möglicherweise eine Alternative in der Darstellung der Nervenquerschnittsfläche des N. X zum Ultraschall. Zukünftige Arbeiten könnten die Nervenquerschnittsfläche des N. X in der MRT mit Messergebnissen aus einer mechanischen Abformung mit Epineurium vergleichen, um Aussagen über die Anwendung der MRT zur präoperativen Einschätzung der Nervenquerschnittsfläche des N. X treffen zu können. Die Nervenquerschnittsfläche des N. X ist abhängig von der Körperseite (rechts signifikant größer als links). Ursächlich sind wahrscheinlich die Innervationsgebiete des N. X, die sich ebenfalls in Abhängigkeit der Körperseite unterscheiden und seitenspezifische Effekte in der Stimulationstherapie hervorrufen (Howland 2014). Der Body-Mass-Index korreliert signifikant mit der Nervenquerschnittsfläche des N. X und beeinflusst den Anteil des Epineuriums und den Anteil der Axone an der gesamten Nervenquerschnittsfläche. Die Nervenquerschnittsfläche des N. X steht in enger Verbindung mit dem Alter der Probanden. Ursächlich könnten die axonale Degeneration oder die an Häufigkeit zunehmenden pathologischen Prozesse mit steigendem Alter sein. Limitiert werden die Ergebnisse dieser Arbeit durch die geringe Fallzahl und die spezifische Altersgruppe (ø 88,4±8,5 Jahre) der Körperspender. Während der Ultraschall die Nervenquerschnittsfläche des N. X in corpore bestimmt, misst die Methode Abformung mit Epineurium die Struktur nach Verletzung der nervalen Integrität. Abschließend handelt es sich bei der histologischen Untersuchung um eine in vitro Messung.:Inhaltsverzeichnis 1. Einleitung 1 1.1 Problemstellung 1 1.2 Klinische Bedeutung der Stimulationstherapie 3 1.2.1 Wirkungsweise der Nervenstimulation für ausgewählte Erkrankungen 3 1.2.2 Implantationsmethodik 5 1.3 Embryologie 6 1.3.1 Entwicklung des N. vagus 6 1.3.2 Entwicklung der Vagina carotica 8 1.4 Morphologie 8 1.4.1 Verlauf des N. X innerhalb der Vagina carotica 8 1.4.2 Relative Position des N. X in der Vagina carotica 10 1.4.3 Durchmesser und NQF des N. X 10 1.4.4 Vaskularisation des N. X 14 1.4.5 Qualitäten und Innervationsgebiete des N. vagus 16 2. Material und Methoden 17 2.1 Untersuchungsmaterial 17 2.2 Das Körperspendewesen des Instituts für Anatomie der Universität Leipzig 19 2.3 Übersicht über den Versuchsaufbau 19 2.3.1 Versuchsprotokoll 21 2.4 Ultraschalluntersuchung 22 2.4.1 Vorbereitungen des Schallgerätes 22 2.4.2 Darstellung des N. X 22 2.4.3 Digitale Dokumentation der NQF 26 2.4.4 Messung der NQF mittels der Software ImageJ 26 2.4.5 Bestimmung der morphologischen Zusammensetzung des N. X 30 2.4.6 Bestimmung der Position des N. X 30 2.4.7 Bestimmung der Nervenform 30 2.5 Makroskopische Präparation des N. X 33 2.6 Die Abformung mit Epineurium des N. X 37 2.6.1 Digitalisierung und Messung der NQF mittels der Software ImageJ 39 2.7 Die histologische Untersuchung des N. X 40 2.7.1 Probenentnahme 40 2.7.2 Fixierung mit Paraformaldehyd 40 2.7.3 Einbettung der Gewebeprobe 40 2.7.4 Herstellung der Gewebeschnitte 43 2.7.5 Färbung der histologischen Schnitte 44 2.7.6 Mikroskopische Untersuchung und digitale Analyse 46 2.8 Literaturrecherche 48 2.9 Statistische Auswertung 49 3. Ergebnisse 52 3.1 Ultraschall, Abformung, Histologie – Gibt es Unterschiede in der ermittelten NQF? 52 3.1.1 Unterschiede zwischen der NQF im Ultraschall und in der Abformung 56 3.1.2 Korrekturfaktor 57 3.1.3 Das Epineurium im Ultraschall – eine Messmethode Abseits der Norm 59 3.1.4 Welchen Einfluss hat die Fixierung des N. X mit Paraformaldehyd? 61 3.2 Morphologische Beobachtungen zum N. vagus 62 3.2.1 Ist die Querschnittsfläche des N. X abhängig von der Körperseite? 63 3.2.2 Ist der N. X eine kreisrunde Struktur? 64 3.2.3 Vaskularisation und Nervenfaszikel 67 3.2.4 Die Position des N. X im Halsbereich 68 3.2.5 Welchen Einfluss hat der BMI auf die Morphologie des N. X? 70 3.2.6 Die Veränderung des N. X im Alter 71 3.3 Wie variabel ist die NQF des N. X? 73 3.4 Die Konsistenz der Bestimmung der NQF – Intraklassen-Koeffizient 73 4. Diskussion 76 4.1 Warum treten signifikante Unterschiede zwischen Ultraschall, Abformung mit Epineurium und Histologie auf? 76 4.1.1 Welche Rolle hat das Epineurium in der Bestimmung der NQF? 77 4.1.2 Ist die Fehleinschätzung der NQF des N. X eine mögliche Ursache für Nebenwirkung bei der Stimulationstherapie? 77 4.1.3 Können Ultraschallmessungen zur NQF des N. X korrigiert werden? 79 4.1.4 Die NQF im Ultraschall in Referenz zur Literatur 79 4.1.5 Alternative bildgebende Verfahren zur Darstellung der NQF des N. X 81 4.2 Die NQF des N. X ist auf der rechten Körperseite größer als links 81 4.3 Einfluss des BMI auf die morphologische Zusammensetzung der NQF des N. X 83 4.4 Der Einfluss des Alters auf die NQF des N. X 84 5. Zusammenfassung 86 6. Literaturverzeichnis 88 7. Abbildungsverzeichnis 95 8. Tabellenverzeichnis 98 9. Anlagen 99 9.1 Ausführliche Informationen zu allen untersuchten Körperspendern 99 10. Eigenständigkeitserklärung 100 11. Lebenslauf 101 12. Publikation 102 13. Danksagung 103