Chemoanatomical separation of vibrissal trigeminal primary afferents in the rat: a special central representation of supraorbital vibrissae.
A choleratoxin B subunit transganglionic labelling technique and NPY immunohistochemistry were applied in the rat to achieve the chemoanatomical separation of myelinated vibrissal primary afferents, previously considered to be morphologically indistinguishable. Further, a special central representation pattern of supraorbital vibrissae was observed in the trigeminal brainstem nuclear complex: (1) Choleratoxin-labelled supraorbital vibrissal primary afferents terminated densely in their appropriate barrelettes in the trigeminal principal sensory nucleus, in the spinal oral subnucleus, in the caudal part of the spinal interpolar subnucleus, and in lamina IV of the caudal part of the spinal caudal subnucleus. (2) A second population of choleratoxin-labelled vibrissal afferents was also observed, terminating only in lamina III of the caudal subnucleus. (3) After peripheral nerve transection, NPY-immunoreactive supraorbital vibrissal primary afferent fibres appeared in their appropriate barrelettes in the principal sensory nucleus and the caudal part of the interpolar subnucleus, while in the caudal part of the caudal subnucleus NPY-immunoreactive vibrissal primary afferent terminals were found exclusively in the inner part of lamina II, extending over the outer part of lamina III. NPY-immunoreactive supraorbital vibrissal primary afferents were never found in the oral subnucleus. In contrast with the rules of the central representation of the mystacial (infraorbital) vibrissae, the multiple representation of the supraorbital vibrissae in the caudal subnucleus and the dense, barrelette-like terminal arborization of the choleratoxin-labelled supraorbital vibrissal primary afferents in the oral subnucleus apparently indicate an enhanced role of supraorbital vibrissae in reflexes that protect the eyes and the head from damage.
Páli
Jenö
J
Neurobiology Research Group, United Research Organization of the Hungarian Academy of Sciences and Semmelweis University, Budapest. pali@ana.sote.hu
Baldauf
Zsolt A
ZA
Szentpétery
Zsófia
Z
Szabo
Zoltán
Z
Herczeg
Livia
L
Görcs
Tamás J
TJ
D000818:Animals; D002772:Cholera Toxin; D007150:Immunohistochemistry; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D009478:Neuropeptide Y / Q000378:metabolism; D009915:Orbit; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D014276:Trigeminal Nerve / Q000502:physiology*; D014278:Trigeminal Nuclei / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology*
D009478:Neuropeptide Y; D002772:Cholera Toxin