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
