Glucocorticoid는 비유기 동물의 유선세포 pro-lactin receptor(PRL-R) 발현을 증가시키며, 전반적인 유선세포의 유합성 작용을 활성시킴으로 유합성 능력을 증진시킨다. 유선세포 PRL-R 발현량 증가는 유생산량 향상과 밀접한 관계를 갖는다. 본 실험은 비유중기의 재래산양의 유합성 능력을 향상시키고자, 0.05. 0.1과 0.2 g hydrocortisone을 5ml의 생리식염수에 현탁하여, 정맥투여하고 유선세포 PRL-R와 $alpha$-유단백 질 mRNAs 발현 량을 조사하였다. 대조구로는 5$mell$의 생리식염수를 정맥투여 하였다. 24시간 후 유선조직을 채취하여 $alpha$-유단백질과 PRL-R mRNA 발현량을 competitive PCR(polymerase chain reaction)로 발현량을 조사하였다. Hydrocortisone 처리 24시간 후 재래산양 유선세포의 PRL-R mRNA 발현량은 대조구의 PRL-R mRNA 발현량과 유의한 차이가 없었다. $alpha$-유단백질 mRNA 발현은 대조구에 비하여 0.05g hydrocortisone투여구는 37%, 0.1g hydrocortisone 투여구는 630%, 0.2g hydrocortisone 투여구는 386% 증가하였다. Hydrocortison 처리에 의한 유선세포 PRL-R mRNA 발현에 변화가 없었으나 $alpha$-유단백질 mRNA 발현 증가는 세포 내 기능성 단백질 발현과 세포 외부로 분비되는 단백질의 시간에 따른 발현양상의 차이인 것으로 사려된다. 본 연구에서 비유중기 재래산양에 hydrocortisone 투여는 $alpha$-유단백질 mRNA 발현을 증가시키는 것으로 나타났다.
Glucocorticoid is activating mammary gland cells for lactating animals, resulting in increasing abilities of the milk synthesis. Expression of the prolactin receptor(PRL-R) in mammary gland cells was closely associated with milk production. To increase lactation ability for the Korean Native Goats at mid-lactation period. 0.05, 0.1. and 0.2 g of hydrocortisone was administrated with 5 $mell$ of saline. and injected into vein. For the control, 5 $mell$ of saline was administrated in to vein. After 24 H, the mammary gland tissue was collected, and mRNA expression rates were investigated for the alpha-casein and PRL-R using competitive PCR(polymerase chain reaction). There was no significant differences between treatment and control groups for the mRNA expression rate of PRL-R in mammary gland cells after 24 h of administration of hydrocortisone. The rate of mRNA expression for the alpha-casein was increased 37%, 630%, and 380% at 0.05, 0.1, and 0.2 g of hydrocortisone administration groups, respectively, comparing with control group. The results suggested that PR L-R mRNA expression of mammary gland cell by administration of hydrocortison was not significant, but increase of the alpha-casein mRNA expression my be differences of expression of functional proteins in the cell and expression patterns of protein secretion time to out of the cell. This study showed increase of alpha-casein mRNA expression by administration of hydrocortisone at mid-lactation period of Korean native goat.
