A 16-Channel Automated Rotometer System for Reliable Measurement of Turning Behavior in 6-Hydroxydopamine Lesioned and Transplanted Rats

Abstract

Unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway in rats result in a massive dopamine (DA) denervation of the ipsilateral striatum. Such animals have proven extremely useful as a model for the study of Parkinson's disease, an idiopathic neurodegenerative disorder of humans. Extensive unilateral DA disruption leaves the rat relatively normal in motor behavior; however, the extent of the lesion can be documented by drug-induced rotational behavior. When given an injection of a dopamine agonist, such as apomorphine or d-amphetamine, a lesioned animal will manifest rotational behavior; the number of turns correlates with the degree of unilateral denervation. In order to identify, for various studies, large numbers of animals with specific levels of denervation, the necessity of an automated and reliable rotational counting system (rotometer) becomes obvious. We have developed such a device that allows up to 16 rats to be tested concurrently with one inexpensive computer. This system is more reliable than, and certainly preferable to, more tedious methods such as videotaping and subsequent manual analysis or various other mechanical systems. Plexiglass, formed into large bowls, serve as the rotometer chambers. We have designed a simple, inexpensive, and accurate counting head that can be manufactured from readily available parts and that is very sturdy and reliable. This, together with a thoracic harness, completes the rotometer assembly. The rotational data, from up to 16 separate channels, is collected by a single-chip microprocessor and sent on a serial line to an IBM-type or Macintosh host computer. There, it is graphically displayed on line and subsequently saved to disk with a novel acquisition program. Files generated are in code readable by most spreadsheet software currently available. Therefore, rotational data can be imported to a number of different spreadsheets and macros used for analysis. In summary, the multiple-channel automation for monitoring turning behavior in rats, described here, is a simple, inexpensive and effective system for accurate and rapid data acquisition and analysis.