Exercise-Induced Changes of Endorphin Contents in Hypothalamus, Hypophysis, Adrenals and Blood Plasma

Abstract

Changes of α-, β-, and γ-endorphin contents were determined in hypothalamus, hypophysis, adrenals and blood plasma in Wistar rats. Four hours of swimming in water at 32 ± 1 °C caused a decrease of the β-endorphin content in hypophysis and hypothalamus. In adrenals, β-endorphin did not change. Changes of α- and γ-endorphins were not parallel to alterations of β-endorphin. In blood plasma, levels of both α- and γ-endorphins were elevated. After 7 days of swim training, 4 hours of swimming caused a slight increase of α-, β- and γ-endorphin levels in hypophysis as well as a pronounced increase of α- and β-endorphins in adrenals. In hypothalamus, β-endorphin content was decreased, but α-endorphin content was on the level of sedentary controls, γ-endorphin content doubled. The levels of endorphins in blood were higher than after a single swimming bout. It was concluded that during acute exercise the activation of the opioid system is mainly based on the augmented release of β-endorphin. In daily repeated exercise the production of β-endorphin increases and exceeds the elevated release in hypophysis and adrenals.

Key words

Adrenals - endorphin - exercise - hypophysis - hypothalamus - training