금식에 의한 시상하부-뇌하수체-성장호르몬 축의 변화 : 암, 수 쥐간의 차이에 관한 연구 Study on the Differences between Male and Female Rats

손숙진,이민아,박승준 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.4

연구배경: 포유동물에서 금식은 성장호르몬의 합성과 분비에 큰 영향을 미침이 알려져 있다. 금식에 의한 성장호르몬 축의 변화의 연구에는 수컷 쥐가 주로 사용되어져 왔다. 그러나 성장호르몬의 합성과 분비 양상은 성에 따른 차이를 보임이 알려져 있다. 본 연구는 금식에 대한 성장호르몬 축의 변화가 성에 따른 차이를 보이는지 알아보기 위해 행해졌다. 방법: 암·수 Sprague-Dawley 쥐 (8∼9주; 5마리/군)를 72시간 동안 금식시키거나 음식물을 자유로이 공급하였다. 혈청 상장호르몬과 IGF-I 농도는 방사면역측정법을 통해 측정하였다. 시상하부 GHRH, SRIF, NPY, 그리고 뇌하수체 성장호르몬의 mRNA는 RNA 소화효소 보호분석법을 통해 측정하였다. 뇌하수체 GHRH 수용체, GHS 수용체, 그리고 SRIF 수용체 mRNA는 역전사-중합효소연쇄반응을 통해 측정하였다. 결과: 금식에 의해 암·수 쥐에서 체중은 각각 18.0%와 17.0% 감소하였다. 금식시킨 수컷 쥐에서는 성장호르몬과 IGF-I 농도가 감소하였으며, 시상하부 GHRH mRNA의 현저한 감소와 NPY mRNA의 현저한 증가를 보였다. GHRH의 감소에도 불구하고 뇌하수체 성장호르몬 mRNA는 금식에 의한 변화를 보이지 않았으며, 오히려 GHRH-R와 GHS-R의 발현은 금식에 의해 현저한 증가를 보였다. 반면에 SRIF 수용체아형 2와 4의 발현은 금식에 의해 현저한 억제를 보였다. 금식에 의한 암컷 쥐에서의 성장호르몬 축의 변화는 대체로 수컷 쥐와 비슷하였으나 다음의 두 가지 중요한 차이를 보였다. 첫째, 성장호르몬 농도는 금식에 의해 저하되지 않았다. 둘째, sst2와 sst4 mRNA의 발현은 금식에 의한 변화를 보이지 않았다. 결론: 수컷 쥐에서 금식에 의한 시상하부 뉴로?타이드, 뇌하수체 GHRH-R, sst2의 발현 변화 등은 기존에 보고된 결과와 일치하는 결과를 얻었다. 금식에 의한 뇌하수체 GHS-R의 발현 증가는 금식시 역시 증가되는 ghrelin과 함께 GHRH에 대한 뇌하수체의 반응성을 증가시키는데 기여할 것으로 사료된다. 이러한 변화는 기전의 일환으로 작용할 가능성도 있는 것으로 보여진다. 수컷 쥐에서 보이는 성장호르몬 농도의 억제가 암컷 쥐에서 관찰되지 않은 이유는 아마도 암컷 쥐에서의 이러한 보상성 기전이 더 우세하게 일어나 결과일 수도 있다고 사료된다. Background: Fasting has a profound impact on GH synthesis, and is released in all mammalian species that have been studied. The male rat has long been used as a model to determine the mechanism on how fasting mediates these changes. However, many aspects of GH synthesis, release and function are known to be gender-dependent. This study was conducted in order to determine if changes in the GH-axis, in response to fasting, differs between the sexes. Methods: Male and female rats(8∼9 weeks; n=5/group) were fasted for 72h, or supplied food ad libitum. The mean circulating serum GH and IGF-I concentrations were measured by radioimmunoassay. The levels of hypothalamic GH-releasing hormone (GHRH), somatostatin (SRIF), neuropeptide Y (NPY) and pituitary GH mRNA were measured using an RNase protection assay. The levels of pituitary GHRH receptor (GHRH-R), GH secretagogue (GHS) receptor (GHS-R) and SRIF receptor (sst 1-5) mRNA were measured by reverse transcription-polymerase chain reaction (RT-PCR). Results: Fasting resulted in a comparable weight loss in both the males and the females, (18.0±0.9%) and (17.0%±0.85), respectively. In the fasted males, there was a characteristic decrease in the serum GH (98±60 vs. 7±4ng/mL) and IGF-I (367±35 vs 152±12ng/mL), associated with a decrease in the hypothalamic GHRH, and an increase in the NPY mRNA, levels of 52±6% and 138±6%, respectively, compared to those of the fed controls (p<0.05). In spite of the reduction in the GHRH, fasting did not alter the levels of the pituitary GH mRNA, and in fact increased the expression of the pituitary receptors, GHRH-R and GHS-R, to 185±15 and 169±25%, respectively, to those of the fed controls. In contrast to the positive impact of fasting on the GH-stimulatory receptors, fasting led to a dramatic decrease in the expressions of the somatostatin receptor subtypes, sst2 (29±5% of Fed) and sst4 (60±7% of Fed). Fasting had comparable effects on the GH-axis of the female rats, with two notable exceptions; first, fasting did not suppress the mean circulating GH levels (16±3 vs. 38±28ng/mL) and second, did not alter the sst2 and sst4 expressions. Conclusion: These results corroborate the other reports regarding the effects of fasting on the expressions of hypothalamic neuropeptides, pituitary GHRH-R and sst2, in male rats. This is the first report demonstration that fasting stimulates the expression of pituitary GHS-R in both sexes. This is of great interest given the fact that ghrelin and GHS-R ligand, is also elevated by fasting. We propose that the upregulation of both ghrelin and GHS-R may play important roles in increasing the sensitivity of the pituitary to GHRH, in that these GH-stimulatory systems work synergistically. These changes may compensate for the fasting-induced suppression of hypothalamic GHRH input. We might speculate that such compensatory mechanisms are dominant in the female rat, in that circulating GH levels are not suppressed by fasting (J Kor Soc Endocrinol 17:473∼485, 2002).

Alternative Isoforms of TonEBP with Variable N-termini are Expressed in Mammalian Cells

김효신,손숙진,김선녀,김용덕,김광진,전병화,박진봉,이상도 대한약리학회 2007 The Korean Journal of Physiology & Pharmacology Vol.11 No.3

Hypertonicity imposes a great deal of stress to cells since it causes rise in cellular ionic strength, which can be reduced by the accumulation of compatible osmolytes. TonEBP plays a central role in the cellular accumulation of compatible osmolytes via transcriptional stimulation of membrane transporters and aldose reductase. Alternatively spliced forms of TonEBP mRNA have previously been reported and two of them showed different transcriptional activity. In the present study, isoform-specific antibodies were produced to confirm the translation of the spliced mRNA to protein. TonEBP was immunoprecipitated by using anti-TonEBP antibody and then immunoblotted using anti-TonEBP or isoform specific antibodies to find out the expression profile of TonEBP isoforms in basal or stimulated condition. From these results, we conclude that all TonEBP isoforms are expressed in mammalian cells and their expression patterns are not same in every cells.

소마토스타틴 수용체

김은희,손숙진,이민아,박희순,정지창,박승준 대한내분비학회 2003 Endocrinology and metabolism Vol.18 No.4

성장호르몬방출호르몬에 대한 반응성을 보이는 뇌하수체 GH3 세포에서?G단백 돌연변이에 의한 소마토스타틴 수용체 mRNA의 변화

김은희,정지창,박승준,손숙진,이민아,서상희,주성희,이담,정현주 대한내분비학회 2005 Endocrinology and metabolism Vol.20 No.4

p66shc Adaptor Protein Suppresses the Activation of Endothelial Nitric Oxide Synthase in Mouse Embryonic Fibroblasts

이상기,김영신,김국성,손숙진,유대군,이권호,이상도,박진봉,전병화 대한약리학회 2006 The Korean Journal of Physiology & Pharmacology Vol.10 No.3

G_Sα 돌연변이 유전자를 영구히 발현하는 GH3 세포주에서 소마토스타틴 수용체 유전자 및 G_i2α, pit-1α 유전자의 발현

박철영,양인명,김은희,손숙진,류미숙,우정택,김성운,김진우,김영설,최영길,박승준 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.2

Background: Cyclic AMP stimulates the expression of the somatostatin (SRIF) receptor (sst1-5) and human growth hormone (GH)-secreting pituitary tumors with the gsp oncogene which increases intracellular cAMP levels, and shows a good inhibitory response of the GH to SRIF. Taken together, we hypothesized that the gsp oncogene may increase the SRIF receptor expression or and factors related to the postreceptor signal transduction of the SRIF, in order to enhance its responsiveness to SRIF. To test this hypothesis, we investigated if the gsp oncogene could increase the sst1, sst2, G_i2α, and pit-1α gene expression in GH3 cells. Methods: GH3 cells were permanently transfected with the plasmid expressing Gsα gene, where the arginine of codon 201 was replaced with histidine. Intracellular cAMP levels and GH concentrations were measured by radioimmunoassays. Gene expressions of the sst1, sst2, G_i2α, and pit-1α were determined by RT-PCR. Results: Intracellular cAMP levels and medium GH release were increased by 1.7 and 2.7-fold in GH3 cells expressing the gsp oncogene, respectively. In GH3 cells expressing the gsp oncogene, the sst1 mRNA levels were decreased, whereas those of the sst2, Gi2α and pit-1α mRNA were increased. A 4-h forskolin (10 μM) stimulation remarkably increased the sst1 and sst2 mRNA levels in GH3 cells expressing wild and mutant Gsα. However, forskolin did not affect the G_i2α and pit-1α mRNA levels. In contrast, SRIF (1 μM, 2 h) decreased the sst2 mRNA levels only in GH3 cells expressing the gsp oncogene. Conclusion: These results suggest that higher expressions of sst2, G_i2α, and pit-1α, induced by the gsp oncogene may be a mechanism by which gsp-positive pituitary tumors show a greater response to SRIF. The discrepancy between these and in vivo results should be explored further

Bupivacaine과 ropivacaine이 Xenopus oocyte에 발현된 HERG 전류에 미치는 영향

김국성,이규승,김효신,손숙진,이상도,김광진,전병화,김윤희,박진봉 충남대학교 의과대학 의학연구소 2003 충남의대잡지 Vol.30 No.1

Bupivacaine is an amide-type local anesthetic widely used for regional anesthesia. Ropivacaine is developed as a less cardiotoxic alternatives to bupivacaine. In the present study, we have analyzed the effects of bupivacaine and ropivacaine on HERG currents expressed in Xenopus oocytes. Bupivacaine and ropivacaine(3∼1,000μM) blocked HERG currents in a concentration dependent manner. EC_(50) was 26.1±3.1μM(n_(R) 0.65±0.04) and 43.5±7.9μM(n_(H) 0.99±0.13) in bupivacaine and ropivacaine, respectively. Bupivacaine and ropivacaine did not affect the activation and deactivation kinetics of HERG channels. However, the drugs decreased the slope conductance measured from fully activated current-voltage relationship curves. These results suggest that bupivacaine and ropivacaine have a similarinhibitory effect on HERG channels, which could be a possible cellular mechanism of LQT or ventricular arrythmia by the drugs.