RESUMO
Objective:To construct a rat model of hypothalamic obesity by two point electrical damage to the ventromedial hypothalamus and arcuate nucleus.Methods:Twenty adult male SD rats of SPF grade were randomly divided into experimental group and sham operation group.A 25GA (0.45 mm) solid iron needle was used, the needle was coated with an insulating layer, and the tip exposed a 0.5 mm conductive area.With reference to The Rat Brain in Stereotaxic Coordinates and using the stereotactic instrument (AP: -2.6 mm, ML: ± 0.6 mm, DV: -9.6 mm) as the coordinate, 1.5 mA current was continuously applied for 25 s, the ventromedial nucleus (VMH) and arcuate nucleus (ARC) of bilateral brain in SD rats was damaged.During the experiment, the body weight(BW), food intake(FI) and water intake(WI) of the two groups were recorded regularly.The rats were sacrificed on the 28th day after the operation, and the changes of periprenal fat mass and body length were measured.The changes of liver and adipose tissue were detected by HE staining method, leptin by ELISA, leptin receptor(LEPR) by Western blot.Results:(1) The body weight of rats in the experimental group ((427.5±17.7)g) and weight gain ((208.5±14.8)g) were significantly increased compared with the rats in the control group((349.2±17.7)g), ((136.2±21.4)g)on the 28th day after operation ( t=7.661, 6.806, both P<0.001). (2) The daily food intake of rats in the experimental group ((44.2±6.6)g) on the 28th day after surgery was significantly higher than that in the control group ((23.0±3.6)g) ( t=6.918, P<0.001). There was no significant difference of the daily drinking water of rats between experimental group((37.5±12.1)ml) and the control group ((35.0±11.8)ml) ( t=0.361, P=0.726). (3) Perikidney fat mass of experimental group rats ((13.4±2.7)g) significantly increased 28 days after operation compared with control group rats((6.3±0.9)g)( t=4.250, P<0.05). The naso-anal length of experimental group((21.8±0.4)cm) was significantly decreased compared with the control group ((23.4±0.2)cm) ( t=-6.788, P<0.01). The Lee index of the experimental group (348.9±8.5) was significantly higher than that of the control group(305.5±4.3)( t=7.898, P<0.01). (4) The serum leptin content ((8 324.10±159.00)μg/L) of the experimental group rats at 28 days after surgery was significantly higher than that of the control group((2 705.31±407.10)μg/L) ( t=25.712, P<0.001). The lateral hypothalamus area (LHA) LEPR protein expression (1.3±0.1) in the experimental group was significantly higher than that in the control group (0.9±0.1) ( t=4.932, P<0.01). Conclusion:Two-point electrical damage to bilateral VMH and ARC of rats can establish hypothalamic obese rat model.
RESUMO
OBJECTIVE@#To investigate the mechanism by which doublecortin promotes the recovery of cytoskeleton in arginine vasopressin (AVP) neurons in rats with electrical lesions of the pituitary stalk (PEL).@*METHODS@#Thirty-two SD rats were randomized into PEL group with electrical lesions of the pituitary stalk through the floor of the skull base (=25) and sham operation group (=7), and the daily water consumption (DWC), daily urine volume (DUV) and urine specific gravity (USG) of the rats were recorded. Four rats on day 1 and 7 rats on each of days 3, 7 and 14 after PEL as well as the sham-operated rats were sacrificed for detection of the expressions of β-Tubulin (Tuj1), doublecortin and caspase- 3 in the AVP neurons of the supraoptic nucleus using immunofluorescence assay and Western blotting.@*RESULTS@#After PEL, the rats exhibited a typical triphasic pattern of diabetes insipidus, with the postoperative days 1-2 as the phase one, days 3-5 as the phase two, and days 6-14 as the phase three. Immunofluorescent results indicated the repair of the AVP neurons evidenced by significantly increased doublecortin expressions in the AVP neurons following PEL; similarly, the expression of Tuj1 also increased progressively after PEL, reaching the peak level on day 7 after PEL. The apoptotic rates of the AVP neurons exhibited a reverse pattern of variation, peaking on postoperative day 3 followed by progressive reduction till day 14. Western blotting showed that the expressions of c-Jun and p-c-Jun were up-regulated significantly on day 3 ( < 0.05) and 7 ( < 0.01) after PEL, while an upregulated p-JNK expression was detected only on day 3 ( < 0.05), as was consistent with the time-courses of neuronal recovery and apoptosis after PEL.@*CONCLUSIONS@#JNK/c-Jun pathway is activated after PEL to induce apoptosis of AVP neurons in the acute phase and to promote the repair of neuronal cytoskeleton by up-regulation of doublecortin and Tuj1 expressions.