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A simple intracranial cannula for the rat
PhysiologyandBehavior,Vol. 7. pp. 281-282. PergamonPress, 1971.Printedin Great Britain
BRIEF COMMUNICATION A Simple Intracranial Cannula for the Rat W. J O S E P H
POTTS
AND
PETER
F. E A S T
Department of Pharmacology, G. D. Searle & Co., Chicago, Illinois 60680, U.S.A. (Received 15 M a r c h 1971)
PorTs, W. J. AND P. F. EAST. A simple intracranial cannulafor the rat. PHYSIOL.BEHAV.7 (2) 281-282, 1971.--A simple cannula is described for introducing chemicals into the brain of the rat. The cannula, which is easily constructed from a disposable hypodermic needle, is small, light weight and durable. Intracerebral injection
Simple cannula
leaving only the stainless steel part of the cannula in contact with animal tissue. In this laboratory cannulae implanted in this manner have proven quite sturdy when used repeatedly for single injections into the ventricles and have only rarely been removed by animals maintained in laboratory cages. Stylets which fit loosely in the cannulae can be tightened
SEVERAL cannula systems have been described which, when implanted stereotaxically, allow the injection of chemicals into specific areas of the brain [1-5]. F o r use in rats, the cannula described by Myers et al. [4] is suitable but is made less useful because of the time required for its construction which is due in part to the drying time of the cement. The cannula described here is more easily constructed and possesses the desirable characteristics of light weight, small size, durability and neglible cost. The outer, or guide cannula was cut from a 21 ga. × 1¼ in. disposable hypodermic needle (Becton-Dickinson) to a length of 15 mm from the middle of the bevelled tip. The internal diameter of the small, tubular terminal lug (No. 1584-2 Keystone Electronics Corporation, New York, N.Y.) was enlarged to 0.033 in. using a No. 66 wire drill. This step was easily accomplished using a small electric hand drill with the lug held in a pin vise. The lug was then slipped onto the 21 ga. needle and soldered, using stainless steel soldering flux, at a point approximately 6 mm from the middle of the bevel. A stylet was formed from 26 ga. stainless steel wire by inserting the wire into the cannula so that it extended to the middle of the bevel. The opposite end of the stylet was then bent at a sharp angle over the top of the cannula to fix its length and thus prevent further insertion into the cannula. The 26 ga. stainless steel stylet wires are available from Becton-Dickinson. Finally an inner, or injector cannula was formed in the same manner as the stylet from a length of 26 ga. stainless steel hypodermic tubing. The bend in the injector cannula fixes its length and allows each injection to be made at the same depth. The completed cannula is shown in diagrammatic cross section in Fig. 1. The cannula when constructed as described above weighs approximately 0.13 g with the stylet in place and is suitable for implantation into the lateral ventricle of the rat using standard stereotaxic techniques. Cranioplast applied around the terminal lug anchors the cannula firmly to the skull
Guide Cannula
FIG. 1. Structure of cannula. The stylet is shown in place with the injector cannula alongside. For details see text. 281
282
POFTS AND EAS l
by bending them slightly to provide a spring tension. This is sufficient to prevent accidental removal of the stylet even during active avoidance procedures. Simultaneous implants of several of these cannulae may be easily achieved because of their small size. Simple modifications to the length of the cannula and the angle of the bevel would allow this cannula to be used for micro-injections into cerebral tissue. For this purpose,
22 ga. needle tubing can be used for the guide cannula and 28 ga. tubing for the injector cannula. In this case the solder lug would be drilled out to 0.028 in. dia. using a No. 70 wire drill. The use of the solder lug in either case, while convenient, is not essential. Replacement could be made with either a ball of solder or a short length of larger diameter tubing sufficient to provide an anchor into the cranioplast cement.
REFERENCES 1. Carmichaei, E., W. Feldberg and K. Fleischhaur. Methods for perfusing different parts of the cats cerebral ventricles with drugs..L PhysioL (Lond.) 173: 354-367, 1964. 2. Feldberg, W. and R. D. Myers. Changes in temperature produced by microinje~tions of amines into the anterior hypothalamus of cats. J. Physiol. (Lond.) 177: 239-245, 1965. 3. Myers, R. D. An intraeranial chemical stimulation system for chronic or self-infusion. J. appl. Physiol. lg: 221-223, 1963.
4. Myers, R. D., G. Casaday and R. B. Holman. A simplified intracranial cannula for chemical stimulation or long-term infusion into the brain. Physiol. Behav. 2: 87-88, 1967. 5. Chisholm, B. and G. Singer. A new type of cannula for central administration of drugs in rats. Physiol. Behav. 5: 1069--1070, 1970.
BRIEF COMMUNICATION A Simple Intracranial Cannula for the Rat W. J O S E P H
POTTS
AND
PETER
F. E A S T
Department of Pharmacology, G. D. Searle & Co., Chicago, Illinois 60680, U.S.A. (Received 15 M a r c h 1971)
PorTs, W. J. AND P. F. EAST. A simple intracranial cannulafor the rat. PHYSIOL.BEHAV.7 (2) 281-282, 1971.--A simple cannula is described for introducing chemicals into the brain of the rat. The cannula, which is easily constructed from a disposable hypodermic needle, is small, light weight and durable. Intracerebral injection
Simple cannula
leaving only the stainless steel part of the cannula in contact with animal tissue. In this laboratory cannulae implanted in this manner have proven quite sturdy when used repeatedly for single injections into the ventricles and have only rarely been removed by animals maintained in laboratory cages. Stylets which fit loosely in the cannulae can be tightened
SEVERAL cannula systems have been described which, when implanted stereotaxically, allow the injection of chemicals into specific areas of the brain [1-5]. F o r use in rats, the cannula described by Myers et al. [4] is suitable but is made less useful because of the time required for its construction which is due in part to the drying time of the cement. The cannula described here is more easily constructed and possesses the desirable characteristics of light weight, small size, durability and neglible cost. The outer, or guide cannula was cut from a 21 ga. × 1¼ in. disposable hypodermic needle (Becton-Dickinson) to a length of 15 mm from the middle of the bevelled tip. The internal diameter of the small, tubular terminal lug (No. 1584-2 Keystone Electronics Corporation, New York, N.Y.) was enlarged to 0.033 in. using a No. 66 wire drill. This step was easily accomplished using a small electric hand drill with the lug held in a pin vise. The lug was then slipped onto the 21 ga. needle and soldered, using stainless steel soldering flux, at a point approximately 6 mm from the middle of the bevel. A stylet was formed from 26 ga. stainless steel wire by inserting the wire into the cannula so that it extended to the middle of the bevel. The opposite end of the stylet was then bent at a sharp angle over the top of the cannula to fix its length and thus prevent further insertion into the cannula. The 26 ga. stainless steel stylet wires are available from Becton-Dickinson. Finally an inner, or injector cannula was formed in the same manner as the stylet from a length of 26 ga. stainless steel hypodermic tubing. The bend in the injector cannula fixes its length and allows each injection to be made at the same depth. The completed cannula is shown in diagrammatic cross section in Fig. 1. The cannula when constructed as described above weighs approximately 0.13 g with the stylet in place and is suitable for implantation into the lateral ventricle of the rat using standard stereotaxic techniques. Cranioplast applied around the terminal lug anchors the cannula firmly to the skull
Guide Cannula
FIG. 1. Structure of cannula. The stylet is shown in place with the injector cannula alongside. For details see text. 281
282
POFTS AND EAS l
by bending them slightly to provide a spring tension. This is sufficient to prevent accidental removal of the stylet even during active avoidance procedures. Simultaneous implants of several of these cannulae may be easily achieved because of their small size. Simple modifications to the length of the cannula and the angle of the bevel would allow this cannula to be used for micro-injections into cerebral tissue. For this purpose,
22 ga. needle tubing can be used for the guide cannula and 28 ga. tubing for the injector cannula. In this case the solder lug would be drilled out to 0.028 in. dia. using a No. 70 wire drill. The use of the solder lug in either case, while convenient, is not essential. Replacement could be made with either a ball of solder or a short length of larger diameter tubing sufficient to provide an anchor into the cranioplast cement.
REFERENCES 1. Carmichaei, E., W. Feldberg and K. Fleischhaur. Methods for perfusing different parts of the cats cerebral ventricles with drugs..L PhysioL (Lond.) 173: 354-367, 1964. 2. Feldberg, W. and R. D. Myers. Changes in temperature produced by microinje~tions of amines into the anterior hypothalamus of cats. J. Physiol. (Lond.) 177: 239-245, 1965. 3. Myers, R. D. An intraeranial chemical stimulation system for chronic or self-infusion. J. appl. Physiol. lg: 221-223, 1963.
4. Myers, R. D., G. Casaday and R. B. Holman. A simplified intracranial cannula for chemical stimulation or long-term infusion into the brain. Physiol. Behav. 2: 87-88, 1967. 5. Chisholm, B. and G. Singer. A new type of cannula for central administration of drugs in rats. Physiol. Behav. 5: 1069--1070, 1970.