Nociceptive Afferents to the Premotor Neurons That Send Axons Simultaneously to the Facial and Hypoglossal Motoneurons by Means of Axon Collaterals

It is well known that the brainstem premotor neurons of the facial nucleus and hypoglossal nucleus coordinate orofacial nociceptive reflex (ONR) responses. However, whether the brainstem PNs receive the nociceptive projection directly from the caudal spinal trigeminal nucleus is still kept unclear. Our present study focuses on the distribution of premotor neurons in the ONR pathways of rats and the collateral projection of the premotor neurons which are involved in the brainstem local pathways of the orofacial nociceptive reflexes of rat. Retrograde tracer Fluoro-gold (FG) or FG/tetramethylrhodamine-dextran amine (TMR-DA) were injected into the VII or/and XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the caudal spinal trigeminal nucleus (Vc). The tracing studies indicated that FG-labeled neurons receiving BDA-labeled fibers from the Vc were mainly distributed bilaterally in the parvicellular reticular formation (PCRt), dorsal and ventral medullary reticular formation (MdD, MdV), supratrigeminal nucleus (Vsup) and parabrachial nucleus (PBN) with an ipsilateral dominance. Some FG/TMR-DA double-labeled premotor neurons, which were observed bilaterally in the PCRt, MdD, dorsal part of the MdV, peri-motor nucleus regions, contacted with BDA-labeled axonal terminals and expressed c-fos protein-like immunoreactivity which induced by subcutaneous injection of formalin into the lip. After retrograde tracer wheat germ agglutinated horseradish peroxidase (WGA-HRP) was injected into VII or XII and BDA into Vc, electron microscopic study revealed that some BDA-labeled axonal terminals made mainly asymmetric synapses on the dendritic and somatic profiles of WGA-HRP-labeled premotor neurons. These data indicate that some premotor neurons could integrate the orofacial nociceptive input from the Vc and transfer these signals simultaneously to different brainstem motonuclei by axonal collaterals

Manual stimulation of the whisker pad after hypoglossal–facial anastomosis (HFA) using a Y-tube conduit does not improve recovery of whisking function

Facial nerve injury is a common clinical trauma involving long-term functional deficits with facial asymmetry leading to associated psychological issues and social hardship. We have recently shown that repair by hypoglossal-facial or facial-facial nerve surgical end-to-end anastomosis and suture [hypoglossal-facial anastomosis (HFA) or facial-facial anastomosis (FFA)] results in collateral axonal branching, polyinnervation of neuromuscular junctions (NMJs) and poor function. We have also shown that another HFA repair procedure using an isogenic Y-tube (HFA + Y-tube) and involving a 10-mm gap reduces collateral axonal branching, but fails to reduce polyinnervation. Furthermore, we have previously demonstrated that manual stimulation (MS) of facial muscles after FFA or HFA reduces polyinnervation of NMJs and improves functional recovery. Here, we examined whether HFA + Y-tube and MS of the vibrissal muscles reduce polyinnervation and restore function. Isogenic Y-tubes were created using abdominal aortas. The proximal hypoglossal nerve was inserted into the long arm and sutured to its wall. The distal zygomatic and buccal facial nerve branches were inserted into the two short arms and likewise sutured to their walls. Manual stimulation involved gentle stroking of the vibrissal muscles by hand mimicking normal whisker movement. We evaluated vibrissal motor performance using video-based motion analysis, degree of collateral axonal branching using double retrograde labeling and the quality of NMJ reinnervation in target musculature using immunohistochemistry. MS after HFA + Y-tube reduced neither collateral branching, nor NMJ polyinnervation. Accordingly, it did not improve recovery of function. We conclude that application of MS after hypoglossal-facial nerve repair using an isogenic Y-tube is contraindicated: it does not lead to functional recovery but, rather, worsens it

Human and climatic impact on mires: a case study of Les Amburnex mire, Swiss Jura Mountains

Modern period long-term human and climatic impacts on a small mire in the Jura Mountains were assessed using testate amoebae, macrofossils and pollen. This multiproxy data analysis permitted detailed interpretations of local and regional environmental change and thus a partial disentanglement of the different variables that influence long-term mire development. From the Middle Ages until a.d. 1700 the mire vegetation was characterised by ferns, Caltha and Vaccinium, but then abruptly changed into the modern vegetation characterised by Cyperaceae, Potentilla and Sphagnum. The cause for this change was most probably deforestation, possibly enhanced by climatic cooling. A decrease in trampling intensity by domestic animals from a.d. 1950 onwards allowed Sphagnum growth and climatic warming in the a.d. 1980s and 1990s may have been responsible for considerable changes in the species composition. The mire investigated is an example of the rapid changes in mire vegetation and peat development that occurred throughout the central European mountain region during the past centuries as a result of changing climate and land-use practice. These processes are still active today and will determine the future development of high-altitude mires