A rapid and convenient freehand method for the implantation of cerebroventricular cannulae in rats

Abstract

The technique of implantation of permanent cannulae, allowing the acute or chronic infusion of solutions into the ventricular system of animals, has been widely used in studies of central nervous system function. Many methods have been published describing the manufacture of cannula systems suitable for intraventricular or intracerebral drug administration in the rat (Myers, 1971; Sparkes and Spencer, 1971; Ott et al., 1974; Rezek and Havlicek, 1975; Malkinson et al., 1977; Crane and Click, 1979). Although such systems can be economical and simple to manufacture, they all suffer from the disadvantage that the implantation technique, generally using conventional stereotaxic methods, is very time-consuming. This greatly limits the number of animals that can readily be prepared by a single worker, which can seriously restrict the application of intracerebroventricular (icv) administration techniques in experiments requiring relatively large numbers of animals. The procedure for implantation of cannulae actually practiced varies from laboratory to laboratory and it is hard to find useful tips and hints. Rather, the details of technique are determined by tradition and acquired by word of mouth; some methods practiced involve the totally freehand implantation of cannula guides, with accuracy being sacrificed for volume of output. In order to ensure the regular production of a sufficiently large number of cannulated animals for behavioral studies, we have created a simple, semifreehand cannulation method which offers the advantages of good accuracy and reproducibility, while taking much less time than more thorough techniques. In the present paper, we describe this rapid technique in sufficient detail to enable its easy implementation. Results of histological studies are also presented.