• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.269-275
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• 1996

Biosynthesis and secretion of anterior pituitary hormones are under the control of specific hypothalamic stimulatory and inhibitory factors. Among them, Growth Hormone Releasing Hormone (GHRH) is the major stimulator of pituitary somatotrophs activating GH gene expression and secretion. Human GHRH is a polypeptide of 44 amino acids initially isolated from pancreatic tumors, and the gene for the hypothalamic form of GHRH is organized into 5 exons spanning over 10 kilobases (kb) on genomic DNA and encodes a messenger RNA of 700-750 nucleotides. Several neuropeptides classically associated with the hypothalamus have been found in the extrahypothalamic regions, suggesting the existence of novel sources, targets and functions. GHRH-like immunoreactivity has been found in several peripheral sites, including placenta, testis, and ovary, indicating that GHRH may also have regulatory roles in peripheral reproductive organs. Furthermore, higher molecular weight forms of the GHRH transcripts were identified from these organs (1.75 kb in testis; 1.75 and >3 kb in ovary). These tissue-specific expression of GHRH gene suggest the existence of unique regulatory mechanism of GHRH expression and function in these organs. In fact, placenta-specific and testis-specific promoters for GHRH transcripts which are located in about 10 kb upstream region of hypothalamic promoter were reported. The use of unique promoters in extrahypothalamic sites could be refered in a different control of GHRH gene and different functions of the translated products in these tissues. Somatotrophs and lactotrophs have been thought to be derived from a common bipotential progenitor, the somatolactotrophs, which give origins to either phenotypes. Although the precise mechanism responsible for the lactotroph differentiation in the anterior pituitary gland has not been yet clalified, there are several candidators for the generation of lactotrophs. In human, the presence of GHRH peptides with different size from authentic hypothalamic form in the normal anterior pituitary and several types of adenoma were demonstrated. Recently our group found the existence of immunoreactive GHRH and its transcript from the normal rat anterior pituitary (gonadotroph> somatotroph> lactotroph), and the GHRH treatment evoked the increased proliferation rate of anterior pituitary cells in vitro. The transgenic mouse models clearly shown that GHRH or NGF overexpression by anterior pituitary cells induced development of pituitary hyperplasia and adenomas particularly GH-oma and prolactinoma. Taken together, we hypothesize that the pituitary GHRH could serve not only as a modulator of hormone secretion but as a paracrine or autocrine regulator of anterior pituitary cell proliferation and differentiation. Interestingly enough, the expression of Pit-1 homeobox gene (the POU class transcription factor) was confined to somatotrophs, lactotrophs and somatolactotrophs in which GHRH receptors are expressed commonly. Concerning the mechanism of somatolactotroph and lactotroph differentiation in the anterior pituitary, we have focused following two possibilities; (1) changes in the relative levels or interactions of both hypothalamic and intrapituitary factors such as dopamine, VIP, somatostatin, NGF and GHRH; (2) alterations of GHRH-GHRH receptor signaling and Pit-1 activity may be the cause of lactotroph differentiation or pituitary hyperplasia and adenoma formation. Extensive further studies will be necessary to solve these complicated questions.

• 한국발생생물학회지:발생과생식
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• 제14권3호
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• pp.199-205
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• 2010

A neurotoxin, 6-hydroxydopamine (6-OHDA) has been widely used to create animal model for Parkinson's disease (PD). The present study was undertaken to examine whether depletion of brain dopamine (DA) stores with 6-OHDA can make alteration in the activities of the testicular steroidogenesis in adult rats. Young adult male rats (3 months old) were received a single dose of 6-OHDA (200 ${\mu}g$ in 10 ${\mu}{\ell}$/animal) by intracerebroventricular (icv) injection, and sacrificed after two weeks. The mRNA levels of steroidogenesis-related enzymes were measured by qRT-PCRs. Serum testosterone levels were measured by radioimmunoassay. Single icv infusion of 6-OHDA significantly decreased the mRNA levels of CYP11A1 (control:6-OHDA group=$1:0.68{\pm}0.14$ AU, p<0.05), CYP17 (control:6-OHDA group=$1:0.72{\pm}0.13$ AU, p<0.05). There were no changes in the mRNA levels of $3{\beta}$-HSD (control:6-OHDA group=$1:0.84{\pm}0.08$ AU) and $17{\beta}$-HSD (control: 6-OHDA group=$1:0.63{\pm}0.20$ AU), though the levels tended to be decreased in the 6-OHDA treated group. Administration of 6-OHDA decreased significantly the mRNA level of StAR when compared to the level of saline-injected control animals (control:6-OHDA group=$1:0.72{\pm}0.08$ AU, p<0.05). Treatment with single dose of 6-OHDA remarkably lowered serum testosterone levels compared to the levels of control group (control:6-OHDA group=$0.72{\pm}0.24:0.13{\pm}0.03ng/m{\ell}$, p<0.05). Taken together with our previous study, the present study demonstrated that the activities of hypothalamus-pituitary-testis hormonal axis could be negatively affected by blockade of brain DA biosynthesis, and suggested the reduced reproductive potential might be resulted in the animals. More precise information on the testicular steroidogenic activities in PD patients and PD-like animals should be required prior to the generalization of the sex steroid hormone therapy to meet the highest standards for safety and efficacy.

• 한국식품과학회지
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• 제38권6호
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• pp.730-737
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• 2006

국내 유통발효식품 중 BAs 함량을 분석하고자 HPLC를 이용한 최적 분석방법을 확립하고, 유통 발효식품 중 BAs 함량을 조사하였다. BAs의 분석에는 0.1N 염산으로 추출한 후 dansyl 유도체를 사용하는 방법이 최적 분석방법으로 선택이 되었고, 검출한계가 0.10 ${\mu}g/mL$ 이하로 나타났다. 식품별 BAs의 함유량은 장류의 경우 한식된장에서 HIS 및 TYR의 함량이 높게 나타났고, 청국장의 경우도 유사하였다. 특히 전통적으로 생산한 된장과 청국장에서 BAs함량이 높게 나타나 종국 및 제조공정의 개선이 필요한 것으로 사료되었다. 간장의 경우 양조간장과 전통간장의 차이가 크지 않았으나, 젓갈류 중에서는 멸치액젓과 까나리 액젓에서 PUT, CAD, TRY, HIS, 및 TYR의 함량이 높게 나타났다. 과실주와 맥주에서는 보통 발효에 관여하는 효모가 BAs 생성능이 없기 때문에 낮은 HIS 수치를 보여주었고, 치즈에서는 TYR의 농도가 약간 높게 나왔을 뿐 전체적인 BAs의 함량은 낮은 수준이었다. 배추김치의 경우 PUT, HIS 및 TYR의 함량이 높게 나타났으나, 김치 제조에 부재료로 들어가는 멸치액젓과 까나리 액젓이 BAs의 함량을 높이는 것으로 추정되었다. 각 식품의 BAs의 함량 결과를 국민건강${\cdot}$영양조사의 일일섭취량에 대입하여 일일섭취량을 조사한 결과 매우 적은 수준으로 나타났으나 TYR의 MAOIs를 복용하는 환자의 경우 BAs가 많이 함유한 식품의 섭취는 가급적 피하는 것이 좋을 것으로 사료된다.