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Projections of extraocular muscle primary afferent neurons to the trigeminal sensory complex in the cat as studied with the transganglionic transport of horseradish peroxidase
242
Neuroscience Letters, 73 (1987) 242 24~ Elsevier Scientific Publishers Ireland Ltd.
NSL 04391
Projections of extraocular muscle primary afferent neurons to the trigeminal sensory complex in the cat as studied with the transganglionic transport of horseradish peroxidase Kosuke Ogasawara 1, Satoru Onodera 2, Toshihiko Shiwa I, Shuya Ninomiya l and Yutaka Tazawa 1 Departments of 1Ophthalmology and 2Anatomy, School of Medicine, lwate Medical University, Morioka (Japan) (Received 21 July 1986; Revised version received and accepted 10 October 1986)
Key words." Extraocular muscle proprioception; Trigeminal nucleus; Transganglionic axonal transport; Cat The central projections of extraocular muscle primary afferent neurons were examined in the cat by means of transganglionic axonal transport of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Injections of the extraocular muscle with WGA-HRP resulted in transganglionic terminal labeling within the ipsilateral trigeminal sensory complex. Although the density of trigeminal projections varied among cases, labeled axons and terminals were heavily and consistently found within the rostroventral portion of the pars oralis of the spinal trigeminal nucleus. The caudal part of the trigeminal principal sensory nucleus occasionally contained moderate labeling but very few deposits of HRP reaction product were noted in the pars interporalis and pars caudalis of the spinal trigeminal nucleus.
In addition to previous physiological studies demonstrating the projections of extraocular muscle proprioception to various areas of the central nervous system, which include the superior colliculus [1,4], the cerebellum [2, 7, 8] and the visual cortex [3, 5], in several species of animals, recent behavioral and clinical studies may be taken to suggest that extraocular muscle proprioceptive signals contribute to the neural control of orienting eye movement and spatial localization [6, 10, 19]. However, the detailed morphological substrates of the central pathway of extraocular muscle proprioception have not yet been fully understood. The present study is an attempt to examine projecting sites of extraocular muscle primary afferent neurons by means of transganglionic axonal transport of wheat germ agglutinin-conjugated horseradish
peroxidase (WGA-HRP). Preliminary results have appeared elsewhere in abstract form [15]. Correspondence." K. Ogasawara, Department of Ophthalmology, School of Medicine, Iwate Medical University, Morioka 020, Japan. 0304-3940/87/$ 03.50 (~) 1987 Elsevier Scientific Publishers Ireland Ltd.
243
In 9 cats (1.8 4.2 kg) the medial rectus, lateral rectus and/or superior rectus muscles were exposed under i.p. pentobarbital anesthesia ( 3 0 4 0 mg/kg) and each muscle was injected with a total of 5/11 of 4% (w/v) W G A - H R P (Sigma) using a Hamilton microsyringe equipped with a 23-gauge needle. To obtain optimal transganglionic labeling, it was necessary to inject into multiple muscles in each experimental animal. Alter a survival period of 3 4 days, the animals were transcardially perfused under deep anesthesia with a mixed solution of 0.5% paraformaldehyde 2.5% glutaraldchyde in 0.1 M phosphate buffer. The lower brainstem and the trigeminal ganglion were cut transversely at 50/~m on a freezing microtome. Sections were processed for histochemical demonstration of HRP with the tetramethylbenzidine method [9] and counterstained with 0.5% Neutral red for light microscopic examination. As for the retrogradely labeled primary afferent neurons of the extraocular muscles following injections of W G A - H R P into the rectus extraocular muscles, they were located in the ipsilateral trigeminal ganglion and the patterned distribution was consistent with its somatotopic organization which indicated that they were restricted within the ophthalmic subdivision of the ganglion. Labeled neurons were neither observed in the mesencephalic trigeminal nucleus nor in the trigeminal sensory complex. These findings are in good agreement with previous reports [14, 17, 18]. Injections of the rectus extraocular muscles with W G A - H R P resulted in transganglionic axonal and terminal labeling within the ipsilateral trigeminal sensory complex. HRP-labeled axons entered the brainstem and accumulated in the ventral portion of the spinal trigeminal tract. Although the density of trigeminal projections varied among cases, labeling was heavily and consistently observed within the rostroventral portion of the pars oralis of the spinal trigeminal nucleus (Figs. 1 and 2). The caudal part of the trigeminal principal sensory nucleus occasionally contained moderate labeling (Fig. 2) but very few deposits of H R P reaction product were noted in the pars interpolaris and pars caudalis of the spinal trigeminal nucleus.
Fig. I. Brighttield photomicrograph of the rostroventral part of the pars oralis of the spinal trigeminal nucleus. Arrowheads show HRP-labeled axons following injection of W G A - H R P into the medial rectus and lateral rectus muscles. Asterisks indicate lrigeminal cells. Bar = 50/Lm.
244
vp
dorsal lateral ~ medial t
ventral
0
0.5ram
Fig. 2. The distribution of HRP reaction products in the trigeminal principal nucleus and pars oralis of the spinal trigeminal nucleus after injection of WGA-HRP into the medial rectus and lateral rectus muscles of cat N2. A series of drawings arranged rostral (upper left, A) to caudal (lower right, D) through levels of the trigeminal motor nucleus (A), the superior olivary nucleus (B and C) and the facial nucleus (D). Vst, spinal trigeminal tract; Vp~ trigeminal principal nucleus: Vo. pars oralis of spinal trigeminal nucleus Vm, trigeminat motor nucleus; 7N. facial nerve: VII. facial nucleus. It m a y not always be possible to preclude uptake o f H R P that m a y have leaked from the injected extraocular muscles in spite o f having a precaution against the diffusion o f H R P to other orbital or periorbital structures, Therefore, to get a confirmation o f H R P uptake by extraocular muscles themselves, 3 cats were used in additional experiments by means o f retrograde transganglionic axonal transport o f H R P , and a small a m o u n t o f W G A - H R P was injected into the pars oralis o f the spinal trigemihal nucleus which was determined as the initial termination site o f the p r i m a r y afferent neurons o f the extraocular muscles. The results show that axons labeled by retrograde transganglionic transport o f H R P were f o u n d a m o n g the extraocular muscle fibers (Fig. 3), which is the first complete d e m o n s t r a t i o n to confirm the projection from the extraocular muscle to the trigeminal sensory nucleus via the trigeminat ganglion. In summary, the present results should provide a basis for further anatomical and physiological studies concerning the projection o f second-order extraocular muscle
245
t
Fig. 3. Brightlield photomicrograph of the medial rectus muscle showing HRP-labeled axons afler injection of W G A - H R P into the pars oralis of the spinal trigeminal nucleus. B a r = 100/tm.
afferent neurons of the cat from the pars oralis of the spinal trigeminal nucleus to the higher brainstem structures such as the superior colliculus [I 1, 13] and the pontine nuclei [12]. On the other hand, it may be noted here that Porter [16] most recently has implicated the pars interpolaris as a recipient zone of the extraocular muscle primary afferents in the monkey. Whether this discrepancy is due to a species difference still remains conjectural. This work has been supported in part by Grant-in-Aid 61480368 for Scientific Research from the Ministry of Education, Science and Culture of Japan. I Abrahams, V.C. and Rose, P.K., Projections ofextraocular, neck muscle and retinal afferents to superior colliculus in the cat: their connection to cells of origin of tectospinal tract, J. Neurophysiol., 38 (1975) I0 18. 2 Batini, C., Buisseret, P. and Kado, R.T., Extraocular proprioceptive and trigeminal projections to the Purkinje cells of the cerebellar cortex. Arch. ltal. Biol., I 12 (1974) 1 17. 3 Buisseret, P. and Maffei, L., Extraoeular proprioceptive projections to the visual cortex, Exp. Brain Res., 28 (1977) 421 425. 4 Donaldson, I.M.L. and Long, A.C., Interactions between extraocular proprioceptive and visual signals in the superior colliculus of the cat, J. Physiol. (London), 272 (1980) 85 110. 5 Enomoto, H., M a t s u m u r a , M. and Tsutsui, J., Projections of extraocular muscle afferents to the visual cortex, Neuro-ophthalmology, 3 (1983) 49 57. 6 Fiorentini, A., Berardi, N. and Maffei, L., Role ofextraocular proprioception in the orienting behavior ofcats, Exp. Brain Res., 48 (1982) [13 120.
246 7 Fuchs, A.F. and Kornhuber, H.H., Extraocular muscle afferent to the cerebellum of the cat, J. Physiol~ (London), 200 (1969) 713-722. 8 Maekawa, K. and Kimura, M., Mossy fiber projections to the cerebellar flocculus from the extraocular muscle afferents, Brain Res., 191 (1980) 313-325. 9 Mesulam, M.-M., Tetramethytbenzidine for horseradish peroxidase neurohistochemistry: a non-carcinogenic blue reaction product with superior sensitivity for visualizing neural afferents and efferents, J. Histochem. Cytochem., 26 (1978) 106-117. I0 Mitsui, Y. and Tamura, O., Proprioception and exodeviations, Br. J. Opthalmol., 65 (1981) 578-584. I 10gasawara, K.. Trigeminotectal projections in cats and the pathway of extraocular muscle proprioception, Neuro-ophthalmology, 1 ( 1981) 219-230. 12 Ogasawara, K. and Hashikawa, T., Trigeminopontine projection in the cat as studied with anterograde and retrograde tracing methods, Soc. Neurosci. Abstr., 12 (1986) in press. 13 Ogasawara, K. and Kawamura, K., Cells of origin and terminations of the trigeminotectal projection in the cat as demonstrated with the horseradish peroxidase and autoradiographic methods, Okajimas Folia Anat. Jap., 58 (1982) 247-263. 14 Ogasawara, K., Onoe, S. and Tazawa, Y., Identification of extraocular muscle afferent neurons in the cat by means of horseradish peroxidase method, Jpn. Rev. Clin. Ophthalmol., 77 (1983) 1182 1185. 15 Ogasawara, K., Shiwa, T. and Tazawa, Y., Morphological substrates for the central pathway of the extraocular muscle proprioception in the cat, Acta Soc. Ophthalmol. Jpn. Suppl. 90 (1986) 163. 16 Porter, J.D., Brainstem terminations of extraocular muscle primary afferent neurons in the monkey, J. Comp. Neurol., 247 (1986) 133-143. 17 Porter, J.D. and Spencer, R., Location and morphology of cat extraocular muscle afferent neurons identified by retrograde transport of horseradish peroxidase, J. Comp. Neurol,, 204 (1982) 56~64. 18 Porter, J.D., Guthrie, B.L. and Sparks, D.L., lnnervation of monkey extraocular muscles: localization of sensory and motor neurons by retrograde transport of horseradish peroxidase, J. Comp. Neurol., 218 (1983) 208 219. 19 Steinbach, M.J. and Smith, D.R., Spatial localization after strabismus surgery: evidence for inflow, Science, 213 (1981) 1407 1409.
Neuroscience Letters, 73 (1987) 242 24~ Elsevier Scientific Publishers Ireland Ltd.
NSL 04391
Projections of extraocular muscle primary afferent neurons to the trigeminal sensory complex in the cat as studied with the transganglionic transport of horseradish peroxidase Kosuke Ogasawara 1, Satoru Onodera 2, Toshihiko Shiwa I, Shuya Ninomiya l and Yutaka Tazawa 1 Departments of 1Ophthalmology and 2Anatomy, School of Medicine, lwate Medical University, Morioka (Japan) (Received 21 July 1986; Revised version received and accepted 10 October 1986)
Key words." Extraocular muscle proprioception; Trigeminal nucleus; Transganglionic axonal transport; Cat The central projections of extraocular muscle primary afferent neurons were examined in the cat by means of transganglionic axonal transport of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Injections of the extraocular muscle with WGA-HRP resulted in transganglionic terminal labeling within the ipsilateral trigeminal sensory complex. Although the density of trigeminal projections varied among cases, labeled axons and terminals were heavily and consistently found within the rostroventral portion of the pars oralis of the spinal trigeminal nucleus. The caudal part of the trigeminal principal sensory nucleus occasionally contained moderate labeling but very few deposits of HRP reaction product were noted in the pars interporalis and pars caudalis of the spinal trigeminal nucleus.
In addition to previous physiological studies demonstrating the projections of extraocular muscle proprioception to various areas of the central nervous system, which include the superior colliculus [1,4], the cerebellum [2, 7, 8] and the visual cortex [3, 5], in several species of animals, recent behavioral and clinical studies may be taken to suggest that extraocular muscle proprioceptive signals contribute to the neural control of orienting eye movement and spatial localization [6, 10, 19]. However, the detailed morphological substrates of the central pathway of extraocular muscle proprioception have not yet been fully understood. The present study is an attempt to examine projecting sites of extraocular muscle primary afferent neurons by means of transganglionic axonal transport of wheat germ agglutinin-conjugated horseradish
peroxidase (WGA-HRP). Preliminary results have appeared elsewhere in abstract form [15]. Correspondence." K. Ogasawara, Department of Ophthalmology, School of Medicine, Iwate Medical University, Morioka 020, Japan. 0304-3940/87/$ 03.50 (~) 1987 Elsevier Scientific Publishers Ireland Ltd.
243
In 9 cats (1.8 4.2 kg) the medial rectus, lateral rectus and/or superior rectus muscles were exposed under i.p. pentobarbital anesthesia ( 3 0 4 0 mg/kg) and each muscle was injected with a total of 5/11 of 4% (w/v) W G A - H R P (Sigma) using a Hamilton microsyringe equipped with a 23-gauge needle. To obtain optimal transganglionic labeling, it was necessary to inject into multiple muscles in each experimental animal. Alter a survival period of 3 4 days, the animals were transcardially perfused under deep anesthesia with a mixed solution of 0.5% paraformaldehyde 2.5% glutaraldchyde in 0.1 M phosphate buffer. The lower brainstem and the trigeminal ganglion were cut transversely at 50/~m on a freezing microtome. Sections were processed for histochemical demonstration of HRP with the tetramethylbenzidine method [9] and counterstained with 0.5% Neutral red for light microscopic examination. As for the retrogradely labeled primary afferent neurons of the extraocular muscles following injections of W G A - H R P into the rectus extraocular muscles, they were located in the ipsilateral trigeminal ganglion and the patterned distribution was consistent with its somatotopic organization which indicated that they were restricted within the ophthalmic subdivision of the ganglion. Labeled neurons were neither observed in the mesencephalic trigeminal nucleus nor in the trigeminal sensory complex. These findings are in good agreement with previous reports [14, 17, 18]. Injections of the rectus extraocular muscles with W G A - H R P resulted in transganglionic axonal and terminal labeling within the ipsilateral trigeminal sensory complex. HRP-labeled axons entered the brainstem and accumulated in the ventral portion of the spinal trigeminal tract. Although the density of trigeminal projections varied among cases, labeling was heavily and consistently observed within the rostroventral portion of the pars oralis of the spinal trigeminal nucleus (Figs. 1 and 2). The caudal part of the trigeminal principal sensory nucleus occasionally contained moderate labeling (Fig. 2) but very few deposits of H R P reaction product were noted in the pars interpolaris and pars caudalis of the spinal trigeminal nucleus.
Fig. I. Brighttield photomicrograph of the rostroventral part of the pars oralis of the spinal trigeminal nucleus. Arrowheads show HRP-labeled axons following injection of W G A - H R P into the medial rectus and lateral rectus muscles. Asterisks indicate lrigeminal cells. Bar = 50/Lm.
244
vp
dorsal lateral ~ medial t
ventral
0
0.5ram
Fig. 2. The distribution of HRP reaction products in the trigeminal principal nucleus and pars oralis of the spinal trigeminal nucleus after injection of WGA-HRP into the medial rectus and lateral rectus muscles of cat N2. A series of drawings arranged rostral (upper left, A) to caudal (lower right, D) through levels of the trigeminal motor nucleus (A), the superior olivary nucleus (B and C) and the facial nucleus (D). Vst, spinal trigeminal tract; Vp~ trigeminal principal nucleus: Vo. pars oralis of spinal trigeminal nucleus Vm, trigeminat motor nucleus; 7N. facial nerve: VII. facial nucleus. It m a y not always be possible to preclude uptake o f H R P that m a y have leaked from the injected extraocular muscles in spite o f having a precaution against the diffusion o f H R P to other orbital or periorbital structures, Therefore, to get a confirmation o f H R P uptake by extraocular muscles themselves, 3 cats were used in additional experiments by means o f retrograde transganglionic axonal transport o f H R P , and a small a m o u n t o f W G A - H R P was injected into the pars oralis o f the spinal trigemihal nucleus which was determined as the initial termination site o f the p r i m a r y afferent neurons o f the extraocular muscles. The results show that axons labeled by retrograde transganglionic transport o f H R P were f o u n d a m o n g the extraocular muscle fibers (Fig. 3), which is the first complete d e m o n s t r a t i o n to confirm the projection from the extraocular muscle to the trigeminal sensory nucleus via the trigeminat ganglion. In summary, the present results should provide a basis for further anatomical and physiological studies concerning the projection o f second-order extraocular muscle
245
t
Fig. 3. Brightlield photomicrograph of the medial rectus muscle showing HRP-labeled axons afler injection of W G A - H R P into the pars oralis of the spinal trigeminal nucleus. B a r = 100/tm.
afferent neurons of the cat from the pars oralis of the spinal trigeminal nucleus to the higher brainstem structures such as the superior colliculus [I 1, 13] and the pontine nuclei [12]. On the other hand, it may be noted here that Porter [16] most recently has implicated the pars interpolaris as a recipient zone of the extraocular muscle primary afferents in the monkey. Whether this discrepancy is due to a species difference still remains conjectural. This work has been supported in part by Grant-in-Aid 61480368 for Scientific Research from the Ministry of Education, Science and Culture of Japan. I Abrahams, V.C. and Rose, P.K., Projections ofextraocular, neck muscle and retinal afferents to superior colliculus in the cat: their connection to cells of origin of tectospinal tract, J. Neurophysiol., 38 (1975) I0 18. 2 Batini, C., Buisseret, P. and Kado, R.T., Extraocular proprioceptive and trigeminal projections to the Purkinje cells of the cerebellar cortex. Arch. ltal. Biol., I 12 (1974) 1 17. 3 Buisseret, P. and Maffei, L., Extraoeular proprioceptive projections to the visual cortex, Exp. Brain Res., 28 (1977) 421 425. 4 Donaldson, I.M.L. and Long, A.C., Interactions between extraocular proprioceptive and visual signals in the superior colliculus of the cat, J. Physiol. (London), 272 (1980) 85 110. 5 Enomoto, H., M a t s u m u r a , M. and Tsutsui, J., Projections of extraocular muscle afferents to the visual cortex, Neuro-ophthalmology, 3 (1983) 49 57. 6 Fiorentini, A., Berardi, N. and Maffei, L., Role ofextraocular proprioception in the orienting behavior ofcats, Exp. Brain Res., 48 (1982) [13 120.
246 7 Fuchs, A.F. and Kornhuber, H.H., Extraocular muscle afferent to the cerebellum of the cat, J. Physiol~ (London), 200 (1969) 713-722. 8 Maekawa, K. and Kimura, M., Mossy fiber projections to the cerebellar flocculus from the extraocular muscle afferents, Brain Res., 191 (1980) 313-325. 9 Mesulam, M.-M., Tetramethytbenzidine for horseradish peroxidase neurohistochemistry: a non-carcinogenic blue reaction product with superior sensitivity for visualizing neural afferents and efferents, J. Histochem. Cytochem., 26 (1978) 106-117. I0 Mitsui, Y. and Tamura, O., Proprioception and exodeviations, Br. J. Opthalmol., 65 (1981) 578-584. I 10gasawara, K.. Trigeminotectal projections in cats and the pathway of extraocular muscle proprioception, Neuro-ophthalmology, 1 ( 1981) 219-230. 12 Ogasawara, K. and Hashikawa, T., Trigeminopontine projection in the cat as studied with anterograde and retrograde tracing methods, Soc. Neurosci. Abstr., 12 (1986) in press. 13 Ogasawara, K. and Kawamura, K., Cells of origin and terminations of the trigeminotectal projection in the cat as demonstrated with the horseradish peroxidase and autoradiographic methods, Okajimas Folia Anat. Jap., 58 (1982) 247-263. 14 Ogasawara, K., Onoe, S. and Tazawa, Y., Identification of extraocular muscle afferent neurons in the cat by means of horseradish peroxidase method, Jpn. Rev. Clin. Ophthalmol., 77 (1983) 1182 1185. 15 Ogasawara, K., Shiwa, T. and Tazawa, Y., Morphological substrates for the central pathway of the extraocular muscle proprioception in the cat, Acta Soc. Ophthalmol. Jpn. Suppl. 90 (1986) 163. 16 Porter, J.D., Brainstem terminations of extraocular muscle primary afferent neurons in the monkey, J. Comp. Neurol., 247 (1986) 133-143. 17 Porter, J.D. and Spencer, R., Location and morphology of cat extraocular muscle afferent neurons identified by retrograde transport of horseradish peroxidase, J. Comp. Neurol,, 204 (1982) 56~64. 18 Porter, J.D., Guthrie, B.L. and Sparks, D.L., lnnervation of monkey extraocular muscles: localization of sensory and motor neurons by retrograde transport of horseradish peroxidase, J. Comp. Neurol., 218 (1983) 208 219. 19 Steinbach, M.J. and Smith, D.R., Spatial localization after strabismus surgery: evidence for inflow, Science, 213 (1981) 1407 1409.