| Objective:In this study, Shenqi Jieyu formula with the effect of tonifying heart and spleen was used to treat postpartum depression (PPD) model animals, and changes in behavior, pathomorphology of brain, related hormones and receptors in neuroendocrine system, monoamine neurotransmitters and their metabolites were tested. It was expected to explore the pathogenesis of neurobiology of PPD and intervening mechanism of Chinese medical therapeutic method of tonifying heart and spleen. And it was also looked forward to explicit the action pathway of Shenqi Jieyu formula and further improve the theory of tonifying heart and spleen treatment for PPD.Methods:Female SD rats were randomly divided into groups of normal (N), sham operation (SO), model (M), Chinese Medicine (CM), western medicine (WM). All the rats were observed at 1,2,4,6w respectively after preparation. M, CM and WM received continuous estrogen and progesterone injection after castration, and there was no intervention for N and sham operation for SO. Then rats were given intragastric administration of distilled water for N, SO and M, Shenqi Jieyu formula for CM, fluoxetine for WM. All of the rats were observed with behaviors tests containing sucrose water consumption (SWC), open-field test (OFT) and forced swimming test (FST) at 1,2,4,6w respectively. After such tests, correlated indexes were detected as follow:â‘ observing nerve cell damages in prefrontal cortex, hippocampus, hypothalamus in rats by hematoxylin and eosin stain;â‘¡checking serum hormone levels of HPA and HPG axis by ELISA and RIA;â‘¢measuring expressions of ER alpha and beta in prefrontal cortex, hippocampus, hypothalamus in brain through immunohistochemistry;â‘£surveying contents of monoamine neurotransmitters and their metabolites in prefrontal cortex, hippocampus with HPLC.Results:1. Observation of general conditions1.1 Appearance and active state:The spirit and active state of M were worse than N and SO. M manifested such symptoms as dull fur, significantly reduced action of hair combing, less explorement and decreased free movement. These symptoms above worst manifested at 1, 2w and partly improved at 4,6w. However, the main status of M was still worse than N at 6w. After drug intervention, the depressive signs above in CM and WM were improved and nearly returned to normal status at 6w. 1.2 Weight:Weight of rats in M at each time point were lower than N and SO (P<0.01, P<0.05). Weight in CM at 2,4,6w and in WM at each time point were higher than M (P<0.01, P<0.05). The condition of rats' weight in M, CM and WM all showed an increasing trend, however, the growing speed of weight in M was obviously slower than CM and WM.2. Observation of praxiology2.1 SWC:SWC in M was lower than N and SO (P<0.01, P<0.05). SWC in WM at 2w and in CM, WM at 4,6w were higher than M (P<0.01). The volume of SWC in M displayed a gradually declined regularity, however, a gradual upward trend in CM and WM.2.2 OFT:Horizontal and vertical scores in M at each time point were lower than N and SO (P<0.01, P<0.05). Horizontal scores in CM, WM at 2,4,6w as well as vertical scores in CM at 1w and in CM, WM at 2,4w were higher than M (P<0.01, P<0.05). Horizontal scores in M, CM, WM and vertical scores in WM all showed a rising trend, while vertical scores in M and CM manifested a formerly declined and then gradually increased trend.2.3 FST:The immobility time in M at each time point were longer than N and SO (P<0.01, P<0.05), struggling time in M at each time point as well as swimming time at 2,4, 6w were shorter than two groups above (P<0.01). Compared with M, the immobility time in CM and WM at each time point reduced (P<0.01, P<0.05), both groups' struggling time at each time point as well as swimming time at 2,4,6w increased (P<0.01, P<0.05). There was a formerly increased and then reduced trend for immobility time in M, and a decreased tendency forward, by following, with gradually increased then rapidly grew downwards pattern for struggling time, meanwhile, a decreased and then gradually increased trend for swimming time. In CM and WM, the regularity manifested gradually decreased for immobility time, gradually increased and then decreased for struggling time, gradually increased for swimming time.3. Observation for pathological structure of brainCell counts of prefrontal cortex and hippocampus in N and SO were abundant, with well-arranged order, well-stacked hyalomitome and distincted nucleolus. Cells in hypothalamus lined in regularity, with normal shape as well. The pathological changes at three places above in M damaged extremely at 1,2w, with unobvious recovery at 4,6w. Cell counts of prefrontal cortex and hippocampus reduced remarkably and some of these were atrophy, with large gap, arranged in loose disorder, cell lightly stained and asymmetrically colored, additionally, cells in hippocampus also partly appeared vacuolization and pyknosis. Cells in hypothalamus swelled obviously, with nonuniformly colored, some of cells also appeared pyknosis. Compared with M, the damaging status of CM and WM at 1w relieved slightly, ameliorated obviously at 2w, with closely recuperation to normal status at 4,6w. 4. Tests for related hormones of neuroendocrine system4.1 Hormones of HPA axis:Compared with N and SO, CRH, ACTH and Cor in M at each time point were higher (P<0.01, P<0.05). CRH in WM at 4,6w as well as ACTH in CM at 2,4,6w and in WM at 2,6w, additionally, Cor in CM, WM at 2,4,6w were all lower than M (P<0.01, P<0.05). ACTH in CM and WM displayed a gradually decreased tendency. In addition, Cor in M, CM and WM showed a gradually raised and then downgraded trend, however, Cor in M manifested the regularity of rising obviously and decreasing slowly.4.2 Hormones of HPG axis:M's GnRH, FSH at each time point as well as LH at 1w, E2 at 2,4,6w were all lower than N and SO (P<0.01, P<0.05), while LH at 2,4,6w as well as E2 at 1w, P at each time point were higher than two groups above (P<0.01, P<0.05). Furthermore, WM's GnRH, E2 at each time point and FSH at 2,4,6w, LH at 1w as well as CM's GnRH, FSH at 2,4,6w, E2 at each time point were all higher than M (P<0.01, P<0.05), while LH at 2, 4.6w and P at each time point in CM and WM were totally lower than M (P<0.01, P<0.05). GnRH, FSH and LH in M, CM and WM all showed the gradually increased trend, while E2 and P appeared obviously decreased regularity. These hormones mentioned above could basically recover to normal level through drug intervention.5. Variation of ER expressions5.1 ER alpha:Expressions in prefrontal cortex, hippocampus and hypothalamus in M at 2,4,6w were less than N and SO (P<0.01, P<0.05), while more than the two groups above at 1w (P<0.01, P<0.05). Compared with M, expressions in prefrontal cortex in CM at 4,6w, prefrontal cortex and hypothalamus in WM at 2,4,6w, hippocampus in CM, WM at 2,4,6w, hypothalamus in CM at each time point all increased (P<0.01, P<0.05). Expressions of the three locations above in M, CM and WM all showed a downward tendency, furthermore, with a remarkable downtrend in M.5.2 ER beta:Both expressions in prefrontal cortex at 1w and in hippocampus, hypothalamus at 1,2w in M were all more than N and SO (P<0.01, P<0.05), however, there had a significant reduction in prefrontal cortex and hypothalamus at 4,6w as well as in hippocasmpus at 6w (P<0.01). Compared with M, expressions in prefrontal cortex at 6w and hippocampus at 4,6w in CM, WM as well as hypothalamus at 4,6w in CM and 2,4,6w in WM all increased (P<0.01, P<0.05). Changes for expressions of ER beta at three locations above in each group made a similar regularity with ER alpha.6. Survey of monoamine neurotransmitters and their metabolites6.1 Monoamine neurotransmitters:Contents of 5-HT, NE, DA in prefrontal cortex and hippocampus in M at each time point were all lower than N and SO (P<0.01, P<0.05). Compared with M, contents of 5-HT, NE in prefrontal cortex in CM at 2,4,6w and WM at each time point as well as in hippocampus in CM, WM at each time point all increased (P<0.01, P<0.05), with the same situation for contents of DA in prefrontal cortex in CM at 4, 6w, WM at 2,4,6w as well as in hippocampus in CM at 1,6w, WM at 1w (P<0.01, P<0.05). 5-HT in prefrontal cortex, hippocampus as well as NE, DA in prefrontal cortex in M all showed a downward trend, while NE in hippocampus displayed a significantly decreased and then slightly increased regularity, in addition, DA in hippocampus manifested the opposite tendency, making a status of increasing by degrees and then falling down.5-HT in prefrontal cortex in CM and in hippocampus in CM, WM as well as NE in prefrontal cortex in WM and in hippocampus in CM all manifested a gradually increased trend, while NE in prefrontal cortex in CM displayed a formerly slightly descended then increased situation, furthermore, DA in hippocampus in CM and WM showed a trend of decreasing.6.2 Metabolites of monoamine neurotransmitters:Contents of 5-HIAA in prefrontal cortex, hippocampus in M at 1w were more than N and SO (P<0.O1, P<0.05), while 5-HIAA for other time points and DOPAC at each time point in both two places were lower than the two groups above (P<0.01, P<0.05). Compared with M, contents of 5-HIAA in prefrontal cortex, hippocampus in CM and WM at 1w reduced (P<0.01, P<0.05), however, with a reversed condition for 5-HIAA in prefrontal cortex at 4,6w as well as both 5-HIAA in hippocampus and DOPAC in prefrontal cortex at 2,4,6w (P<0.01, P<0.05).5-HIAA in prefrontal cortex, hippocampus in M all displayed a decreased trend, while with a first gradually descended and then increased regularity for DOPAC in prefrontal cortex. Additionally,5-HIAA in prefrontal cortex and hippocampus in CM, WM showed an obviously grew downwards then gradually increased situation, whereas DOPAC in hippocampus in CM illustrated an opposite trend of formerly increasing and then descending.Conclusions:1. Through suddenly hormones withdraw after continuous injection of estrogen and progesterone to build PPD animal model, PPD rats manifested a series of behavioral changes: active and exploring movements attenuated, interests reduced, the response of struggle to escape out of the despair environment declined. Furthermore, the histomorphology of brain also had the corresponding structural damages. This model, which possesed a well repetitiveness, successfully simulated the status of PPD in etiology, meanwhile, it might also provide a good platform for further exploration for pathogenesis as well as new drug discovery in PPD.2. Shenqi Jieyu formula with the effect of tonifying heart and spleen could not only obviously improve depressive behaviors in PPD rats, but also promote the recovery of pathological injury of brain tissue. Compared with the control drug SSRIs fluoxetine, both interventions had coincidental curative effects for depressive behaviors and pathological harm of brain in model rats, which might provide a theoretical groundwork for tonifying heart and spleen treatment for PPD and also establish the basis for pharmacodynamics study with Shenqi Jieyu formula.3. There existed balanced disorders in serum hormones of HP A and HPG axises, as well as dysfunction in E-specific combinationed ER alpha and beta, furthermore, content reduction of monoamine neurotransmitters and their metabolites in brain in PPD model rats. These alteration mentioned above in each system might be the important neurobiological material base during the occurrence and development in PPD.4. Shenqi Jieyu formula could remarkably improve related hormones'level of the neuroendocrine system and promote ER expressions in brain, additionally, increase the contents of monoamine neurotransmitters and their metabolites. Adjusting each of these independent systems as well as regulating various systems as a whole steady state may the major route for therapeutic effects educing and also play a very important role in the whole process.
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