Localization, morphology, and immunohistochemistry of spinal cord and dorsal root ganglion neurons that innervate the gastrocnemius and superficial digital flexor muscles in cattle.
OBJECTIVE
To determine the location, morphology, and neurochemical code of spinal cord and dorsal root ganglion neurons that innervate the gastrocnemius muscle (GM) and superficial digital flexor muscle (FDSM) in cattle.


METHODS
5 healthy Friesian male calves.


METHODS
2 different types of neuronalretrograde fluorescent tracers (fast blue and diamidino yellow) were injected into the GM and FDSM, respectively. The neurochemical code (substance P, calcitonin gene-related peptide, galanin, and neuronal nuclear protein) of labeled neurons was investigated by immunohistochemistry.


RESULTS
Neurons innervating the GM and FDSM were located along the L6-S2 spinal cord segments and ganglionic levels. A cranial-to-caudal topographic distribution for each muscle was found, indicating that the motor nuclei of the 2 muscles are organized by a somatotopic pattern. The GM and FDSM motoneurons were immunoreactive only for calcitonin gene-related peptide, whereas the afferent neurons were immunoreactive for all of the neurochemical markers considered.


CONCLUSIONS
In our study, location and the extent of neurons that supply the GM and FDSM of cattle were characterized completely. Because the GM and FDSM are involved in spastic paresis of calves and it is thought that spastic paresis results from an excessive activity of the neuromuscular spindle reflex arc, findings in our study may be useful for further electrophysiologic and clinical studies. Knowledge of the neurochemical code of neurons that supply the GM and FDSM in healthy calves could be used to compare chemical alterations in the same neuronal population of affected calves.
Chiocchetti
Roberto
R
Department of Veterinary Morphophysiology and Animal Production, University of Bologna, 40064 Ozzano dell'Emilia, Bologna, Italy.
Grandis
Annamaria
A
Bombardi
Cristiano
C
Clavenzani
Paolo
P
Spadari
Alessandro
A
Gentile
Arcangelo
A
Bortolami
Ruggero
R
D000578:Amidines / Q000378:metabolism; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D019004:Galanin / Q000378:metabolism; D005727:Ganglia, Spinal / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D006614:Hindlimb / Q000294:innervation*; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D008856:Microscopy, Fluorescence / Q000662:veterinary; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism; D013373:Substance P / Q000378:metabolism
D000578:Amidines; D009687:Nuclear Proteins; C031455:diamidino compound 253-50; D013373:Substance P; C037945:diamidino yellow; D019004:Galanin; D015740:Calcitonin Gene-Related Peptide