Brainstem origin of duodenal vagal preganglionic parasympathetic neurons. A WGA-HRP study in the ferret (Mustela Putorius Furo), a human model

The projections of vagal brainstem neurons to the duodenal segment of the gastrointestinal tract were studied in the ferret using the WGA-HRP neurohistochemical technique. Fourteen adult ferrets with weights ranging from 800 gm to 1500 gm were used for the study. The muscular wall of the duodenum of six ferrets was injected with 0.1 ml of 5 WGA-HRP in 0.5 M sodium chloride. The eight remaining ferrets were used as controls. Two of these had injections of 0.1 ml normal saline into the muscular wall of the duodenum. The second set of two ferrets was injected with 0.1 ml of 5 WGA-HRP in buffer after bilateral truncal vagotomy. The third set of two ferrets received intraperitoneal injection of 0.1 ml of 5 WGA-HRP while, in the last set, the tracer was injected into the hepatic portal vein. Following the injections, the ferrets were allowed to survive for 48-72 hours after which each ferret was perfused transcardially first with normal saline followed by a fixative containing 1 paraformaldehyde and 1.25 glutaraldehyde in 0.1 M phosphate buffer, pH 7.4 at room temperature and finally with 10 buffered sucrose at 4 degrees C. Transverse serial frozen sections of the brainstem were then taken and processed for WGA-HRP neurohistochemistry and were analyzed under light and dark-field illuminations. The analyses of the sections taken from the six ferrets injected with WGA-HRP revealed neurons labelled with the tracer in the dorsal motor nucleus of the vagus nerve (DMNV). Sections taken from the control ferrets did not reveal any WGA-HRP labelled neurons in the brainstem

Modulated intra-train spike responses in the cat superior cervical ganglion in vivo

Se encontró el conocido patrón de dos etapas de facilitación y depresión de las respuestas posganglionares a estimulación de alta frecuencia (24 Hz) de los nervios preganglionares. Se observó que la etapa de depresión estaba exagerada bajo bloqueo parcial con hexametonio, pero que no la afectaba la sección transversa parcial del tronco preganclionar. A frecuencia baja (8 Hz) el reclutamiento normal se tornaba en el patrón familiar de dos etapas bajo dosis moderadas de hexametonia. La evolución de la depresión bajo los efectos del antagonista nicotínico competitivo dihidro-ß-eritroidina fue muchísimo más lenta que bajo la acción del hexametonio. Estas observaciones pueden atribuirse al conocido efecto de consumo y dependencia del hexametonio