Brain Research Bulletin,
All rights of reproduction
Vol. I, pp. 493-494, 1976. Copyright 0 ANKHO International in any form reserved. printed in the U.S.A.
Inc,
BRIEF COMMUNICATION Optic Nerve Sectioning in Rats’ CURT P. RICHTER Psyc~obio~o~ca~ Laboratoty, Johns Hopkins U~i~ers~~ School of Medicine and Hospital, Baltimore, MD 21205 (Received 31 March 1976)
RICHTER,
C. P. Optic nerve sectioning
in rats. BRAIN
RES. BULL.
l(5)
493-494,
1976. - A simple certain method
was described for blinding rats with a minimum of trauma by sectioning of the optic nerves. Optic nerves
Blinding
FOR MANY behavior experiments, especially involving effects of light on various periodic phenomena of rats and other rodents, it becomes necessary either to keep the animals in constant darkness in light-proof boxes or to blind them. The high degree of light sensitivity of rats and other ‘dark’ active rodents make it very difficult to service animals in the boxes without affecting their 24-hr clocks; also it is difficult to monitor the boxes for presence of light leaks, Blinding by enucleation or sectioning of the optic nerves thus become the only certain methods of eliminating light. In early experiments, I enucleated the eyes by cutting above a ligature placed around the protruded bulb. This technique had several technical and esthetic shortcomings: it usually involved much bleeding, even though temporary; it occasionally left enough retinal tissue at the end of the nerve stump to maintain full light reactions; and finally, the animals with enucleated eyes may have been under some stress. After many dissections I devised the following operation which eliminated all the shortcomings of earlier attempts. The fine drawings made by Mr. P. D. Malone in Fig. 1 illustrate the various steps involved in this operation. Here are the instructions for this operation: (1) Place well-narcotized rat (nembutal) on its side; with fingers push skin apart on both sides of orbit to make it protrude; slip open paper clip (opening slightly smaller than diameter of orbit) under protruding orbit (see ‘B’). (2) Exert slight pressure on orbit with one arm of clip to hold orbit steady. (3) With a fine strong pair of forceps in one hand pick up the sclera near junction with orbit; with a fine pair of forceps in the other hand tease sclera away from orbit as near as possible to its insertion (see ‘A’). This prevents
FIG. 1. Illustrates various steps involved in sectioning of the optic nerves in rats.
1Part of study carried on under a grant (MH-00576) from National Institutes of Mental Health. 493
RICHTER
494
bleeding from vessels located lower down and fully frees sclera from choroid. (4) After freeing sclera from over half of orbit (see ‘B’) allow freed lip of sclera to slip under front arm of paper clip (see ‘C’). (5) Pick up lip of sclera under paper clip and exert slight pull rotating orbit by pressure from front arm of clip exposing under surface of orbit and optic nerve. For best exposure of optic nerve keep paper clip perpendicular to axis of head.
(6f With wing scissors cut optic nerve in full view away from orbit. With practice both nerves can be cut in five to ten minutes without any loss of blood. This operation leaves the orbit intact in its normal place. Sectioning of optic nerves in hundreds of rats has not resulted in an infection in a single animal. This method of blinding has been used in a variety of experiments on the L4-hr and other clocks of rats and hamsters [ 1, 2, 3 1.
REFERENCES I.
2.
Richter, C. P. Biological Clocks In ~edj~i?le and Psychiatry. Springfield, IL: Charles C. Thomas, 1965. Richter. C. P. Sleeo and activitv: Their relation to the 24hour clock. In: Sleep and Altered States of Consciousness. Association for Research in Nervous and Mental Disease, Volume XLV, Baltimore, MD: The Williams and Wilkens Company, 1967, pp. 8-29.
3.
Richter, C. P. Deep hvDothermia and its effects on the 24hour clock of rats and han%ers. Johns Hopkins Med. J. 136: l-10, 1975.
All rights of reproduction
Vol. I, pp. 493-494, 1976. Copyright 0 ANKHO International in any form reserved. printed in the U.S.A.
Inc,
BRIEF COMMUNICATION Optic Nerve Sectioning in Rats’ CURT P. RICHTER Psyc~obio~o~ca~ Laboratoty, Johns Hopkins U~i~ers~~ School of Medicine and Hospital, Baltimore, MD 21205 (Received 31 March 1976)
RICHTER,
C. P. Optic nerve sectioning
in rats. BRAIN
RES. BULL.
l(5)
493-494,
1976. - A simple certain method
was described for blinding rats with a minimum of trauma by sectioning of the optic nerves. Optic nerves
Blinding
FOR MANY behavior experiments, especially involving effects of light on various periodic phenomena of rats and other rodents, it becomes necessary either to keep the animals in constant darkness in light-proof boxes or to blind them. The high degree of light sensitivity of rats and other ‘dark’ active rodents make it very difficult to service animals in the boxes without affecting their 24-hr clocks; also it is difficult to monitor the boxes for presence of light leaks, Blinding by enucleation or sectioning of the optic nerves thus become the only certain methods of eliminating light. In early experiments, I enucleated the eyes by cutting above a ligature placed around the protruded bulb. This technique had several technical and esthetic shortcomings: it usually involved much bleeding, even though temporary; it occasionally left enough retinal tissue at the end of the nerve stump to maintain full light reactions; and finally, the animals with enucleated eyes may have been under some stress. After many dissections I devised the following operation which eliminated all the shortcomings of earlier attempts. The fine drawings made by Mr. P. D. Malone in Fig. 1 illustrate the various steps involved in this operation. Here are the instructions for this operation: (1) Place well-narcotized rat (nembutal) on its side; with fingers push skin apart on both sides of orbit to make it protrude; slip open paper clip (opening slightly smaller than diameter of orbit) under protruding orbit (see ‘B’). (2) Exert slight pressure on orbit with one arm of clip to hold orbit steady. (3) With a fine strong pair of forceps in one hand pick up the sclera near junction with orbit; with a fine pair of forceps in the other hand tease sclera away from orbit as near as possible to its insertion (see ‘A’). This prevents
FIG. 1. Illustrates various steps involved in sectioning of the optic nerves in rats.
1Part of study carried on under a grant (MH-00576) from National Institutes of Mental Health. 493
RICHTER
494
bleeding from vessels located lower down and fully frees sclera from choroid. (4) After freeing sclera from over half of orbit (see ‘B’) allow freed lip of sclera to slip under front arm of paper clip (see ‘C’). (5) Pick up lip of sclera under paper clip and exert slight pull rotating orbit by pressure from front arm of clip exposing under surface of orbit and optic nerve. For best exposure of optic nerve keep paper clip perpendicular to axis of head.
(6f With wing scissors cut optic nerve in full view away from orbit. With practice both nerves can be cut in five to ten minutes without any loss of blood. This operation leaves the orbit intact in its normal place. Sectioning of optic nerves in hundreds of rats has not resulted in an infection in a single animal. This method of blinding has been used in a variety of experiments on the L4-hr and other clocks of rats and hamsters [ 1, 2, 3 1.
REFERENCES I.
2.
Richter, C. P. Biological Clocks In ~edj~i?le and Psychiatry. Springfield, IL: Charles C. Thomas, 1965. Richter. C. P. Sleeo and activitv: Their relation to the 24hour clock. In: Sleep and Altered States of Consciousness. Association for Research in Nervous and Mental Disease, Volume XLV, Baltimore, MD: The Williams and Wilkens Company, 1967, pp. 8-29.
3.
Richter, C. P. Deep hvDothermia and its effects on the 24hour clock of rats and han%ers. Johns Hopkins Med. J. 136: l-10, 1975.
