Bannai M, Ichikawa M, Nishihara M, Takahashi M
Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
Brain Res. 1998 Feb 16;784(1-2):305-15. doi: 10.1016/s0006-8993(97)01349-8.
In the ventromedial hypothalamus (VMH), gamma-aminobutyric acid (GABA) plays a role in regulating feeding and running behaviors. The GABA synthetic enzyme, glutamic acid decarboxylase (GAD), consists of two isozymes, GAD65 and GAD67. In the present study, the phosphorothioated antisense oligodeoxynucleotides (ODNs) of each GAD isozyme were injected bilaterally into the VMH of male rats, and food intake, body weight and locomotor activity were monitored. ODNs were incorporated in the water-absorbent polymer (WAP, 0.2 nmol/microliter) so that ODNs were retained at the injection site. Each antisense ODN of GAD65 or GAD67 tended to reduce food intake on day 1 (day of injection=day 0) though not significantly. An injection combining both antisense ODNs significantly decreased food intake only on day 1, but body weight remained significantly lower than the control for 5 days. This suppression of body weight gain could be attributed to a significant increase in locomotor activity between days 3 and 5. Individual treatment with either ODNs did not change locomotor activity. The increase in daily locomotor activity in the group receiving the combined antisense ODNs occurred mainly during the light phase. Neither vehicle (WAP) nor control ODN affected food intake, body weight and locomotor activity. Histological studies indicated that antisense ODN distributed within 800 micron from the edge of the area where WAP was located 24 h after the injection gradually disappeared within days, but still remained within 300 micron m distance even 7 days after the injection. Antisense ODN was effectively incorporated by all the cell types examined, i.e., neurons, astrocytes and microglias. Further, HPLC analysis revealed that antisense ODNs of GAD isozymes, either alone or combined, decreased the content of GABA by 50% in VMH 24 h after the injection. These results indicate that suppression of GABA synthesis by either of the GAD isozymes is synergistically involved in suppressing food intake and enhancing locomotor activity in rat VMH.
在腹内侧下丘脑（VMH）中，γ-氨基丁酸（GABA）在调节进食和奔跑行为中发挥作用。GABA合成酶谷氨酸脱羧酶（GAD）由两种同工酶GAD65和GAD67组成。在本研究中，将每种GAD同工酶的硫代磷酸化反义寡脱氧核苷酸（ODN）双侧注射到雄性大鼠的VMH中，并监测食物摄入量、体重和运动活动。ODN被掺入吸水聚合物（WAP，0.2 nmol/微升）中，以便ODN保留在注射部位。GAD65或GAD67的每种反义ODN在第1天（注射日=第0天）虽未显著降低食物摄入量，但有降低趋势。两种反义ODN联合注射仅在第1天显著降低了食物摄入量，但体重在5天内仍显著低于对照组。体重增加的这种抑制可能归因于第3天至第5天运动活动的显著增加。单独使用任何一种ODN治疗均未改变运动活动。接受联合反义ODN的组中每日运动活动的增加主要发生在光照期。载体（WAP）和对照ODN均未影响食物摄入量、体重和运动活动。组织学研究表明，注射后24小时，反义ODN分布在距WAP所在区域边缘800微米内，数天内逐渐消失，但即使在注射7天后仍保留在300微米距离内。反义ODN被所有检测的细胞类型有效摄取，即神经元、星形胶质细胞和小胶质细胞。此外，高效液相色谱分析显示，GAD同工酶的反义ODN单独或联合使用，在注射后24小时使VMH中的GABA含量降低了50%。这些结果表明，GAD同工酶中的任何一种对GABA合成的抑制协同参与了大鼠VMH中食物摄入的抑制和运动活动的增强。
