Intraventricular administration of a FIV-envelope protein induces sleep architecture changes in rats

Fifteen adult male Sprague-Dawley rats were implanted with a set of electrodes for standard sleep recordings. A stainless steel cannula was also implanted into the lateral ventricle of these rats. Fifteen additional rats were implanted with a cannula alone. Rats with electrodes were habituated for 3 days or more to the recording environment, then placed into 3 groups (n = 5). One group received saline (i.c.v.), while the other two groups received either the feline immunodeficiency virus envelope glycoprotein (FIV SU-Env) or a fragment of the Epstein-Barr virus envelope glycoprotein (EB gp 105). Rats were then recorded for electrographic sleep-wake cycle evaluation for the following 4 h. Core temperature was assessed through a thermistor probe inserted into the rectum, immediately before and 1, 2, 3 and 4 h after the i.c.v. treatment condition. Results demonstrated that compared to saline, FIV SU-Env increased wakefulness and decreased REM sleep throughout the 4 h of recording. Likewise, FIV SU-Env decreased SWS2 for 2 h. In addition, EB gp105 administration elicited minor modifications of the sleep-wake cycle, causing only a transient reduction of REM sleep in the first hour of recording. None of the treatments altered body temperature. These findings strongly support and extend studies in FIV-infected cats in which we have found similar sleep abnormalities. In addition, these results are consistent with the hypothesis that the FIV SU-Env proteins are responsible for these neurological disturbances. Immunologic and physiologic similarities reported for FIV and HIV infection as well as virologic properties of FIV indicate that FIV is a suitable model to study AIDS neuropsychiatric disorders and may also be used to asses potential therapeutics.