Antiserum to growth hormone decreases sleep in the rat

To determine whether an acute withdrawal of growth hormone (GH) alters sleep, the effects of antiserum to GH (GH-AS) on sleep were studied in the rat. Sleep-wake activity and cortical brain temperature (Tc) were recorded for 2 days after systemic injection of physiological saline. Then, one group of rats (n = 6) received GH-AS whereas another group of rats was injected with normal rabbit serum (n = 6). The injections were given 1 h before light onset, and the rats' behaviors were recorded for 23 h during the subsequent 12-hour light and 12-hour dark period. Sleep and Tc were not altered after normal rabbit serum. The durations of both rapid eye movement sleep (REMS) and non-REMS (NREMS), and the EEG slow-wave activity during NREMS were significantly suppressed during the light period following the injection of GH-AS. Tc tended to decrease for 3 h and a small rise was observed thereafter during the light period, but these changes were not statistically significant. The assay of GH in plasma samples obtained at 30-min intervals for 5 h after injection of normal rabbit serum or GH-AS verified the decreases in plasma GH concentrations in response to GH-AS. It is suggested that GH may promote sleep possibly via some metabolic actions.