Effects of intraventricular beta-endorphin and D-ALA2-methionine-enkephalinamide on behaviour, spectrum power of electrocortical activity and body temperature in chicks.

In chicks (Gallus domesticus) the effects of beta-endorphin and D-Ala-2-methionine-enkephalinamide given into the third cerebral ventricle on behaviour, electrocortical activity and body temperature were studied. Dose-dependent behavioural stuporous state, decrease in painful stimuli and hypothermic effects were observed after both peptides. Electrocortical high-amplitude slow frequency waves occurred during behavioural sedation and stupor. Spectrum power analysis has allowed to quantify the ECoG activity and has revealed an increase in total voltage output with a predominant increase within the lower spectrum frequencies. The hypothermic effects were significantly more marked when chicks were kept at ambient temperature below their thermoneutral range. Behavioural, electrocortical and body temperature effects were rapidly reversed by naloxone showing that these effects are mediated through an activation of specific opioid receptors.