Differential regulation of beta-endorphin in the anterior pituitary, intermediate lobe, hypothalamus and brain stem

The influence of adrenalectomy (adx), betamethasone (BET) and 11-deoxycorticosterone (DOC) on beta-endorphin-like-immunoactivity (beta-END-LI) in plasma, anterior (AP) and neuro-intermediate lobe (N-IL) of pituitary, hypothalamus (HT) and brain stem (BS) was studied in rats. One day or three weeks after adx animals were injected i.m. for five consecutive days with 0.4mg/kg BET or 3.4mg/kg DOC. Six days after adx beta-END-LI was increased in BS and plasma after four weeks there was an elevation in plasma and AP. BET suppressed beta-END-LI in plasma of both sham-adx and adx animals six days after operation and in the N-IL after six days of adx. DOC led to an increase of beta-END-LI in HT after sham-adx and to a reduction in the N-IL after four weeks of adx. These observations demonstrate that beta-END-LI is regulated differently at its sites of synthesis in the AP, N-IL and HT.