[Role of opioid peptides in the pathogenesis of vestibulo-autonomic disorders]

The study was carried out using 12 noninbred male cats and 14 white rats. In response to vestibulo-autonomic disorders the rats showed a decrease of beta-endorphin in the midbrain, medulla oblongata and hypothalamus as well as a reduction of met-enkephalin in the hypothalamus and medulla oblongata. The concentration of met-enkephalin in the adrenals increased and that of beta-endorphin in blood did not change. This may be attributed to the intraneuronal redistribution of opioids and their transfer to the pituitary or release into the cerebrospinal fluid. Opioid variations give evidence that vestibuloautonomic disorders in rats do not stimulate the pituitary-adrenal system. The cats were exposed to vestibulo-autonomic disorders and subsequent intracerebroventricular administration of regulatory peptides or injection of opiate receptor blockers into the chemoreceptor trigger zone. It was demonstrated that naloxone, gamma-endorphin and des-Tyr-gamma-endorphin were effective in protecting the vestibular function whereas ICI 154, 129 (a selective antagonist of delta-receptors) was practically ineffective.