[Effects of tibial second toe free flap bridged with blood flow and nerve in the treatment of severe flexion contracture of the proximal interphalangeal joint]

Objective: To investigate the effects of tibial second toe free flap bridged with blood flow and nerve in the treatment of severe flexion contracture of the proximal interphalangeal joint. Methods: A retrospective observational study was conducted. From March 2013 to October 2019, 9 patients with severe flexion contracture (type Ⅲ) of the proximal interphalangeal joint after trauma operation, conforming to the inclusion criteria, were hospitalized in Suzhou Ruihua Orthopaedic Hospital, including 5 males and 4 females, aged from 17 to 62 years. After the contracture tissue affecting the extension of the proximal interphalangeal joint was cut off, and the scar tissue was resected, the size of the volar wound near the proximal interphalangeal joint in extended position was 2.0 cm×1.0 cm-2.5 cm×1.5 cm, with the length of proper digital artery and nerve defect being 1.0-1.5 cm. A free flap of the same size as the wound was cut from the tibial side of the second toe and transplanted to repair the wound, and the defective proper digital artery and nerve was repaired by bridging with the tibial proper plantar digital artery and nerve of about 1.5 cm in length. The full-thickness skin graft was taken from the proximal tibial side of the lower leg to repair the wound at flap donor site. The wound at skin graft donor site was sutured directly. The survival of flap and skin graft was observed after operation. The patients were followed up, and at the last follow-up, the recovery of the affected finger and the second toe, including the donor and recipient areas were observed, the two-point discrimination distances of the flap repaired site and the pulp of the affected finger were observed and measured at the same time, the blood flow patency of bridged vessel of the affected finger was examined by Allen test, and the function of the proximal interphalangeal joint of the affected finger was evaluated according to Chinese Medical Association's standard for the range of motion of proximal interphalangeal joint. Results: The flaps and skin grafts survived smoothly after operation. The follow-up after operation lasted for 5 to 22 months, with a mean of 10 months. At the last follow-up, the flap repaired site had good shape, good color and texture, with the two-point discrimination distance being 9-12 mm, and the two-point discrimination distance of the pulp of the affected finger was 6-10 mm; the Allen test results of the affected fingers were all negative (i.e., the bridged vessels had good blood flow patency), with no recurrence of flexion contracture, and the function of the proximal interphalangeal joint was evaluated as excellent; the skin graft area of the second toe was not ruptured but was a little pigmented, and the flexion and extension activities of toe were good. Conclusions: The tibial second toe free flap bridged with blood flow and nerve has reliable therapeutic effect in the treatment of severe flexion contracture of the proximal interphalangeal joint, and the color and texture of the flap repaired area are good. Bridging to repair the severely contracted proper digital artery and nerve is beneficial to improve the blood supply of the finger body and rebuild the sensation.

[Comparative study of the effects between second toe tibial dorsal artery flap and second toe tibial plantar proper artery flap in repairing finger skin and soft tissue defects]

Objective: To compare the effects between second toe tibial dorsal artery flap (2-TDAF) and second toe tibial plantar proper artery flap (2-TPPAF) in repairing finger skin and soft tissue defects. Methods: A retrospective cohort study was conducted. From January 2019 to June 2020, 27 patients with skin and soft tissue defects at the fingertips with area of 1.5 cm×1.2 cm-2.6 cm×1.8 cm after debridement who met the inclusion criteria were admitted to Suzhou Ruihua Orthopaedic Hospital, including 21 males and 6 females, aged 19-59 (37±10) years. According to flap repair methods used in the defective fingers, the patients were divided into 2-TDAF group (12 cases) and 2-TPPAF group (15 cases). The area of 2-TDAF ranged from 1.5 cm×1.2 cm to 2.5 cm×1.6 cm, and the area of 2-TPPAF ranged from 1.7 cm×1.3 cm to 2.6 cm×1.8 cm. Full-thickness skin grafts from the medial side of the ipsilateral leg were grafted to the wounds in donor sites, and the wounds in donor sites of skin grafts were directly sutured. Flap arterial diameter, flap excision time, flap survival situation of patients in 2 weeks after operation, and follow-up time were recorded. At the last follow-up, the two-point discrimination distance of flap graft site, total action motion (TAM) of the finger joints, and wound healing of the flap donor site were recorded; the Vancouver scar scale (VSS) was used to score the scar in donor area of the second toe and the recipient area of fingers; the appearance and self-satisfaction subscales of the Michigan hand outcomes questionnaire (MHQ) were used to evaluate the affected finger. Data were statistically analyzed with independent sample t test or Fisher's exact probability test. Results: The flap artery diameter of patients in 2-TDAF group was 0.35-0.80 (0.56±0.14) mm and the flap cutting time was (14.0±2.7) min, which were significantly shorter than 0.80-1.35 (1.02±0.16) mm and (19.7±3.4) min in 2-TPPAF group (with t values of 7.81 and 4.79, respectively, P<0.01). The flaps of patients in the 2 groups in recipient areas survived well in 2 weeks after operation, and the wounds in donor areas of flaps of patients in the 2 groups healed well at the last follow-up. There was no statistically significant difference in the postoperative follow-up time, and two-point discrimination distance of flap graft site, TAM of the finger joints, VSS score of scar in the second toe donor site and the finger recipient site, and the appearance and self-satisfaction of MHQ scores of the affected finger at the last follow-up (P>0.05). Conclusions: Compared with 2-TPPAF, 2-TDAF has a shallower anatomical layer and shorter time for surgical flap removal, which can preserve the proper arteries and nerves at the base of the toes and reduce the damage to the donor site.

[Multiple free homologous superficial peroneal artery perforator flaps of crus for repair of multiple hand wounds]

Objective: To explore the effects of multiple free homologous superficial peroneal artery perforator flaps of crus for repair of multiple hand wounds. Methods: From November 2017 to December 2018, eight cases with eighteen hand wounds were hospitalized in our unit. Among them, wounds were distributed in the forefinger and middle finger in four cases, wounds were distributed in the middle finger and ring finger in two cases, wounds were distributed in the forefinger, middle finger, and ring finger in one case, and wounds were distributed in the middle finger, ring finger, and little finger in one case. The area of skin defect ranged from 1.5 cm×0.8 cm to 4.0 cm×3.0 cm. There were 4 males and 4 females, aged 34-62 years. Wounds of six cases were repaired by two free superficial peroneal artery perforator flaps from homolateral crus, and those of two cases were repaired by three free superficial peroneal artery perforator flaps from homolateral crus. Superficial peroneal artery and its accompanying vein of flap were anastomosed by end to end with digital artery and palmar or dorsal subcutaneous vein of recipient site during the operation. The area of flap ranged from 2.5 cm×1.2 cm to 5.0 cm×4.0 cm. No nerve was harvested during the operation, and donor site was sutured directly. The survival of the flaps and the healing of donor sites were recorded. During follow-up, the recovery of donor and recipient sites was observed. Results: All flaps survived well, donor site healed well. No vascular crisis occurred. Follow-up for 4 to 12 months showed that the appearance of flap was satisfactory with good color, texture, elasticity, and function. Protective sensation of recipient site was recovered. Five months after operation, flap of finger pulp in one case was swollen slightly with two-points discrimination of 10 mm, which received the thinning surgery. Obvious scar formation was not observed in donor site of crus. The appearance of the donor site was good without functional damage. Conclusions: The application of multiple free homologous superficial peroneal artery perforator flaps of crus to repair the multiple hand wounds has advantages of easy acquisition, easy operation, little effect on donor sites, and satisfactory clinical effects.

[Clinical effects of extra-long lateral femoral supercharged perforator flaps in repair of foot and ankle wounds]

Objective: To investigate the clinical effects of extra-long lateral femoral supercharged perforator flaps in repair of ankle and foot wounds. Methods: From March 2014 to October 2018, 16 patients with foot and ankle injuries were admitted to our hospital and left large area of wounds on foot and ankle after emergency treatment. There were 13 males and 3 females, with age of 27 to 60 years. The area of the wounds ranged from 14 cm×10 cm to 40 cm×17 cm. The wounds were repaired with extra-long lateral femoral supercharged perforator flaps. The widths of flaps in 8 patients were longer than 8 cm, and the bilobed flaps were designed to repair the wounds. The area of the flaps ranged from 12 cm×5 cm to 40 cm×9 cm. During the operation, 54 perforators were detected, with an average of 3.2 perforators in each flap, and 36 source arteries of perforators were detected. The blood vessel trunk of 15 patients was descending branch of the lateral femoral circumflex artery, and their supercharged mode was anastomosis of the bulky perforator of descending branch of the lateral femoral circumflex artery with the oblique branch of the lateral femoral circumflex artery and/or medial femoral circumflex artery or the descending branch of superficial illiac circumflex artery. The blood vessel trunk of 1 patient was oblique branch of the lateral femoral circumflex artery, and the supercharged mode of the patient was anastomosis of the oblique branch of the lateral femoral circumflex artery with the bulky perforator of the descending branch of the lateral femoral circumflex artery. The wounds were covered with the flaps after supercharged blood vessel anastomosis, and blood vessels in the donor sites were anastomosed with those in the recipient sites. The donor site was sutured directly. The survival of the flap after the operation and healing time of the wound, and the flap condition, the two-point discrimination distance of flap in patients who were reconstructed with sensation, the recovery of the ankle function, and the appearance of the donor site during follow-up were recorded. Results: A total of 17 flaps in 16 patients were designed, including 8 bilobed flaps and 9 non-lobulated flaps. Sixteen flaps in 15 patients survived. Vascular crisis occurred in the flap of one patient, and the flap survived when the vascular crisis was relieved by the second operation. The healing time of foot and ankle wounds ranged from 12 to 90 days. All the lateral femoral donor sites healed completely. During follow-up of 8 to 48 months, flaps in 2 patients were slightly bloated and were trimmed in 6 months after the operation. The other flaps were with good appearance, soft texture, good elasticity, and no rupture or ulceration. The two-point discrimination distances of flaps ranged from 7 to 16 mm in 8 patients who were reconstructed with sensation, and the other flaps recovered protective sensation. The flexion and extension function of ankle joint recovered well, and the walking function was not affected significantly. All donor sites formed linear scar, with no deep tissue infection such as osteomyelitis. Conclusions: The application of extra-long lateral femoral supercharged perforator flaps to repair the large area of wounds in foot and ankle can significantly reduce damage to donor sites and has advantages of rich blood supply and good safety, thus it has satisfactory clinical effects.

[The relationship between fragmented QRS complex and coronary collateral circulation in patients with chronic total occlusion lesion without prior myocardial infarction]

Objective: To explore the relationship between fragmented QRS complex(fQRS) and coronary collateral circulation(CCC) in patients with chronic total occlusion(CTO)lesion without prior myocardial infarction. Methods: This retrospective study analyzed 238 consecutive patients with CTO lesion in one of the major coronary arteries from May 2014 to October 2015 in our department. Patients were divided into poor CCC group (grade 0 and 1, 58 cases) and good CCC group(grade 2 and 3, 180 cases) based on Rentrop's classification of CCC. The fQRS was defined as the presence of an additional R wave or notching of R or S wave or the presence of fragmentation in two contiguous electrocardiogram leads corresponding to a major coronary artery territory. Multivariate logistic regression was used to analyze the relationship between CCC and fQRS on electrocardiogram. Results: Compared with good CCC group, patients in poor CCC group had older age((65.2±8.9)years old vs. (60.3±10.1) years old, P=0.03), higher plasma glucose ((7.22±3.00) mmol/L vs.(6.31±1.83)mmol/L, P=0.04), and lower left ventricular ejection fraction ((45.2±11.4)% vs. (51.2±13.5)%, P=0.02). None of patients had Rentrop grade 0, the presence of fQRS on ECG in patients with Rentrop grade 1, grade 2, and grade 3 CCC was 69.0% (40/58), 48.6% (35/72) , and 19.4% (21/108), respectively (P<0.01). The presence of fQRS were higher in poor CCC group than in good CCC group (69.0%(40/58)vs. 31.1%(56/180), P<0.01), and number of leads with fQRS were higher in poor CCC group than in good CCC group (3(0, 4)vs.0(0, 3), P<0.01). Multivariate logistic regression analysis demonstrated that poor CCC growth in patients with CTO lesion without prior myocardial infarction was independently related to the presence of fQRS (OR=3.659, 95%CI 1.619-8.217, P<0.01). Conclusion: Poor CCC in patients with CTO lesion without prior myocardial infarction is independently related to the presence of fQRS on electrocardiogram.

Generation of cloned transgenic cats expressing red fluorescence protein

A method for engineering and producing genetically modified cats is important for generating biomedical models of human diseases. Here we describe the use of somatic cell nuclear transfer to produce cloned transgenic cats that systemically express red fluorescent protein. Immature oocytes were collected from superovulating cat ovaries. Donor fibroblasts were obtained from an ear skin biopsy of a white male Turkish Angora cat, cultured for one to two passages, and subjected to transduction with a retrovirus vector designed to transfer and express the red fluorescent protein (RFP) gene. A total of 176 RFP cloned embryos were transferred into 11 surrogate mothers (mean = 16 +/- 7.5 per recipient). Three surrogate mothers were successfully impregnated (27.3%) and delivered two liveborn and one stillborn kitten at 65 to 66 days of gestation. Analysis of nine feline-specific microsatellite loci confirmed that the cloned cats were genetically identical to the donor cat. Presence of the RFP gene in the transgenic cat genome was confirmed by PCR and Southern blot analyses. Whole-body red fluorescence was detected 60 days after birth in the liveborn transgenic (TG) cat but not in the surrogate mother cat. Red fluorescence was detected in tissue samples, including hair, muscle, brain, heart, liver, kidney, spleen, bronchus, lung, stomach, intestine, tongue, and even excrement of the stillborn TG cat. These results suggest that this nuclear transfer procedure using genetically modified somatic cells could be useful for the efficient production of transgenic cats.

Ethanol modulates GABA(B) receptor expression in cortex and hippocampus of the adult rat brain

Using in situ hybridization, RNase protection assay and Western blot, we studied the effects of ethanol on the expression levels of GABA(B) receptor mRNA and protein in the cortex and hippocampus from adult rat brain. The results showed that ethanol significantly increased GABA(B1) and GABA(B2) receptor protein expression in the cortex, whereas only GABA(B2) was increased in the hippocampus. GABA(B) receptor agonist baclofen could partially reverse the effect of ethanol. Further studies of the mRNA levels defined that GABA(B1) mRNA levels were significantly increased in the hippocampus, with no significant changes of GABA(B2) mRNA levels. Moreover, GABA(B1) and GABA(B2) receptor mRNA levels were increased on 3-week ethanol treatment. Finally, GABA(B) agonist baclofen and antagonist phaclofen showed significant decreasing effects on GABA(B1) receptor mRNA levels in the cortex, but not in the hippocampus. These results were further confirmed by in situ hybridization. Thus, the present results showed the effects of ethanol on GABA(B) receptors in the cortex and hippocampus, implying the possible role of GABA(B) receptor in ethanol effects. The effects of GABA(B) receptor agonist and antagonist suggested that the possible mechanisms underlying that GABA(B) receptor modulated the behavioral effect induced by ethanol.

Esters of chlorambucil with 2-substituted 1,4-dihydroxy-9,10-anthraquinones as multifunctional anticancer agents

Novel twelve esters of chlorambucil with 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinone were synthesized and tested for their antitumor activity in mice bearing S-180 ascitic cells as well as cytotoxic activity against L1210 cells. Eight of them were highly cytotoxic on L1210 cells (ED(50), <6 microg mL(-1)) and derivatives 1 and 12 (T/C, 200 and 205%) appeared more active in vivo than chlorambucil (T/C, 168%).

[Changes in the state of phosphorylation of DARPP-32 of gerbil striatum during ischemia]

Using the mongolian gerbil model of transient forebrain ischemia by bilateral carotid arteries occlusion, the levels of phosphorylation and the amount of DARPP-32 in striatum were measured by back-phosphorylation and Western-blotting assay in vitro. Transient forebrain ischemia had no effect on the immunoreaction of DARPP-32 in striatum, but the state of phosphorylation of DARPP-32 showed a significant change. The [32P] phosphate incorporation in DARPP-32 decreased after 2, 7 or 10 min of ischemia, but increased after a 5-min ischemia. In contrast, the result of back-phosphorylation in vivo was opposite to that obtained in vitro.

Effect of dopamine depletion on DARPP-32 protein in ischemic rat striatum

AIM

To study the effects of dopamine depletion on the phosphorylation level, intracellular distribution, and mRNA expression of DARPP-32 in the ischemic striatum and to elucidate the mechanisms underlying the ischemic injury.

METHODS

A complex model of SN lesioning with 6-OHDA to deplete dopamine and four vessels occlusion for inducing forebrain ischemia was constructed in rats. DARPP-32 was investigated with autoradiogram, immunohistochemistry and in situ hybridization.

RESULTS

The [32P]phosphate incorporation of DARPP-32 was reduced in vitro following ischemia. However, the [32P]phosphate incorporation, the numbers of positive neurons, and mRNA expression of DARPP-32 were increased in SN lesioning plus ischemic rats with denervated striatum.

CONCLUSION

Dopamine depletion reduced the DARPP-32 phosphorylation in vivo following ischemia, and protected DARPP-32 immunoreactivity and mRNA expression level against the reduction induced by ischemia.

Relevance between striatal expression of Fos, proenkephalin mRNA, prodynorphin mRNA and rotation induced by l-stepholidine in 6-hydroxydopamine-lesioned rats

AIM

To study that l-stepholidine (SPD) regulates the expression of proenkephalin (PENK) and prodynorphin (PDYN) mRNA and Fos in the striatum after rotational test in the 6-hydroxydopamine (6-OHDA)-lesioned rats.

METHODS

PENK and PDYN mRNA levels were examined with in situ hybridization, and Fos expression was detected with immunocytochemistry. The data were semi-quantified with image analyzer.

RESULTS

(1) Following repeated SPD treatment, the rotation was kept on high activity in the 6-OHDA-lesioned rats. (2) SPD significantly elicited Fos expression in both sides of striatum, particularly in the denervated one. Repeated administration of SPD, Fos expression declined on both sides, particularly in the intact one. (3) In the denervated striatum of 6-OHDA-lesioned rats, the PENK mRNA level was extremely increased vs that in the intact striatum. This high level of PENK mRNA was significantly reduced by 7-d treatments of SPD. SPD also reduced the level of PENK mRNA in the intact striatum. However, the level of PDYN mRNA did not show significant change in both sides of striatum after denervation or SPD treatment.

CONCLUSION

In the 6-OHDA-lesioned rats, the rotation induced by SPD was kept on a high activity, which was in pace with the inducement of Fos expression and the reduction of expression of PENK mRNA in the denervated striatum. But then the lesion and SPD treatment had no remarkable effect on the expression of PDYN mRNA.

Modulation of medical prefrontal cortical D1 receptors on the excitatory firing activity of nucleus accumbens neurons elicited by (-)-Stepholidine

(-)-Stepholidine (SPD), with D1 agonistic action, elicited an excitatory firing activity of nucleus accumbens (NAc) neurons by intravenous administration, but this effect was hardly observed by iontophoresis of SPD into the NAc. The present study intends to determine whether D1 receptors in the medial prefrontal cortex (mPFC) are involved in the action of SPD on the firing activity of NAc neurons in the chloral hydrate-anesthetized male rats. The results showed that the intra-mPFC microinjected SCH-23390 (D1 antagonist, 30 mM), but not the D2 antagonist spiperone (30 mM), significantly attenuated the enhanced firing activity induced by intravenous injection of SPD (2 mg/kg). Similarly, the excitatory firing of NAc neurons was also exhibited by the microinjection of either SPD or D1 agonist SKF-38393 into the mPFC. The SPD-induced excitatory effect was in a dose-dependent way from 277.8 +/- 51.3% (10 mM) to 1105.4 +/- 283.5% (30 mM) of NAc basal firing, which was completely reversed by SCH-23390 (i.v.). Furthermore, the direct D1 agonistic action of SPD on the mPFC neuron was observed with microiontophoresis. These results indicate that SPD possesses a direct agonistic action on the mPFC D1 receptors, by which it modulates the firing activity of NAc neurons.

[Effects of tetrahydroberberine on peripheral vascular dopamine DA1 and DA2 receptor subtypes]

OBJECTIVE

To study the effect of tetrahydroberberine (THB) on the peripheral vascular dopamine DA1 and DA2 receptors.

METHOD

Using isolated vascular rings method.

RESULT

THB(0.1-10 mumol.L-1) shifted the dose-response curves to the right in a nonparallel fashion and decreased the maximal response (Emax) of both the fenoldopam(FODA, a selective DA1 agonist)-induced and the propyl-butyl-dopamine(PBDA, a selective DA2 agonist)-induced vasorelaxation, showing a non-competitive antagonistic action. The pD'2 values of THB for FODA in the renal, pulmonary and mesenteric arteries were 5.29, 5.37 and 5.46, respectively, while for PBDA in the mesenteric and femoral arteries were 5.53 and 5.48, respectively. The potencies of this antagonistic action were weaker than those of SCH23390, a selective DA1 antagonist, domperidone, a selective DA2 antagonist and l-SPD, a mixed DA1/DA2 antagonist, domperidone, a selective DA2 antagonist and l-SPD, a mixed DA1/DA2 antagonist.

CONCLUSION

THB is a mixed peripheral DA, and DA2 receptor antagonist similar to l-SPD.

2-(1 -hydroxyiminoalkyl)-1 ,4-dimethoxy-9,10-anthraquinones: synthesis and evaluation of cytotoxicity

A series of 2-(1-hydroxyiminoalkyl)-1,4-dimethoxy-9,10-anthraquinones (oximes) was synthesized and evaluated for cytotoxicity against L1210 cells and A549 cells. These oximes showed a greater cytotoxic activity compared to those of 2-(1-hydroxyalkyl)-1,4-dimethoxy-9,10-anthraquinones as the hydroxyalkyl bioisosteres. The enhanced cytotoxicity assumed to be due to the improved water solubility of the hydroxyimino group. Moreover, it was found that the cytotoxicity of the oximes decreased with elongation of alkyl groups at the side chain. All of the synthesized compounds showed higher cytotoxicity against L1210 cells than A549 cells.

I-stepholidine facilitates inhibition of mPFC DA receptors on subcortical NAc DA release

AIM

To determine whether the D1 agonistic action of (-)-stepholidine (SPD) on the medial prefrontal cortex (mPFC) neuron is involved in the modulation of evoked subcortical dopamine (DA) release from nucleus accumbens (NAc) of rats.

METHODS

With the microinjection of SPD into the mPFC, the ventral tegmental area (VTA)-stimulated or amphetamine (AMP)-evoked DA efflux in the NAc was detected by microdialysis + HPLC-ECD in the 6-hydroxydopamine (6-OHDA)-lesioned and intact rats.

RESULTS

The depletion of DA in the mPFC did not modify both the basal level and the VTA-stimulated DA efflux in the NAc, but significantly facilitated the AMP (20 mumol.L-1)-evoked DA efflux within the NAc. It indicates that the mPFC DA system is involved in the regulation of evoked DA release in the NAc. Besides, the AMP-evoked increase of the extracellular DA release in the NAc was significantly attenuated by SPD (10, 30 mmol.L-1) microinjection into the mPFC, though this injection of SPD could not alter the response of DA release by the stimulation of the VTA. Furthermore, the inhibitory effect of SPD on the AMP-evoked DA efflux could be partially reversed by intravenous administration of D1 antagonist Sch-23390 (1 mg.kg-1), but not by D2 antagonist spiperone.

CONCLUSION

SPD is capable of enhancing the function of D1 receptors in the mPFC, by which it facilitates the inhibition of DA release in the NAc.

Synthesis and evaluation of the antitumor activity of 2-substituted 1,4-dihydroxy-9,10-anthraquinones

2-(1-Hydroxyiminoalkyl)-1,4-dimethoxy-9,10-anthraquinones were demethylated to produce 2-(1-hydroxyiminoalkyl)-1,4-dihydroxy-9,10-anthraquinones (1,4-dihydroxy-9,10-anthraquinone, DHAQ), oxime hydroxyl groups were in turn acylated to give the corresponding 2-(1-acyloxyiminoalkyl)-DHAQ derivatives. The anti-proliferative activity of 2-(1-hydroxyiminoalkyl)-DHAQ derivatives was found to be dependent on the size of an alkyl chain. Thus, DHAQ analogues with alkyl chains longer than heptyl had negligible anti-proliferative activity, whilst those compounds possessing shorter chains demonstrated moderate anti-proliferative activity (ED50, 2.73-19.21 microM). However, the antitumor activity as expressed by T/C values did not correlate with the anti-proliferative activity; 2-(1-hydroxyiminononyl)-DHAQ with an ED50 value of more than 20 microM exhibited potent antitumor activity (T/C, 166%). Only four of the 2-(1-hydroxyiminoalkyl)-DHAQ analogues showed good antitumor activity (T/C, > 150%); 2-(1-hydroxyiminobutyl)-DHAQ (T/C, 163%), 2-(1-hydroxyiminopentyl)-DHAQ (T/C, 180%) and 2-(1-hydroxyiminononyl)-DHAQ (T/C, 166%). Acylation of the hydroxyl group of these oximes enhanced the anti-proliferative activity and antitumor effects; 2-(1-propanoyloxyiminopropyl)-DHAQ (ED50, 4.41 microM; T/C, 221%) vs. 2-(1-hydroxyiminopropyl)-DHAQ (ED50, 14.64 microM; T/C, 100%) and 2-(1-propanoyloxyiminobutyl)-DHAQ (ED50, 2.65 microM; T/C, 202%) vs. 2-(1-hydroxyiminobutyl)-DHAQ (ED50, 16.43 microM; T/C, 163%).

Arcuate nucleus of hypothalamus involved in analgesic action of l-THP

AIM

To study the role of the arcuate nucleus of hypothalamus in analgesic action of l-tetrahydropalmatine (l-THP).

METHODS

The horseradish peroxidase (HRP) retrograde tracing, HRP retrograde tracing combined with immunohistochemistry, lesion of nucleus, tail-flick test, and intra-PAG injection were used in the present study.

RESULTS

HRP retrograde tracing results showed that the striatum or accumbens nucleus connect with PAG by two pathways: 1) striatum or accumbens nucleus-->arcuate nucleus-->PAG; 2) striatum or accumbens nucleus-->habenula-->PAG. It was found that neurons in the arcuate nucleus projecting to PAG were mainly beta-endorphin neurons as observed by HRP retrograde tracing combined with immuno-histochemistry. After lesion of the arcuate nucleus, the analgesic action of l-THP (40 mg.kg-1, i.p.) was abolished, while lesion of the habenula had no such effect. Moreover, intra-PAG injection of naloxone (2, 3 micrograms) could markedly attenuate the analgesic action of l-THP (40 mg.kg-1, i.p.) in a dose-dependent manner.

CONCLUSION

beta-Endorphin neurons in the arcuate nucleus play an important role in the analgesic action of l-THP.

Tetrahydroprotoberberines inhibit lipid peroxidation and scavenge hydroxyl free radicals

AIM

To study the effects of tetrahydroprotoberberines (THPB) on rat liver and brain lipid peroxidation (LPO) and oxygen free radicals generation.

METHODS

The malondialdehyde (MDA) levels in rat brain and liver homogenates, induction of MDA by Fe(2+)-Vit C in mitochondria, OH. generation by Fenton reaction, and O2.- generation by pyrogallol oxidation were observed in vitro.

RESULTS

(1) THPB lowered the MDA contents in the liver homogenate and mitochondria, and the IC50 values of l-THPB-18 and l-stepholidine (SPD) in the liver mitochondria were 3.1 and 12.7 mumol.L-1 respectively. SPD decreased the MDA contents in the brain homogenate and mitochondria with IC50 values of 102 and 35.0 mumol.L-1 respectively. (2) THPB scavenged OH., and the IC50 values of l-THPB-18 and SPD were 0.21 and 3.8 mumol.L-1 respectively, but no effect on O2.- was observed.

CONCLUSION

THPB could reduce the MDA contents and scavenge OH. and THPB-18 was the most potent amongst them.

Electrophysiological study on biphasic firing activity elicited by D(1) agonistic-D(2) antagonistic action of (-)-stepholidine in nucleus accumbens

Our previous work has demonstrated that (-)-stepholidine (SPD) has dual action, ie D(1) agonistic-D(2) antagonistic action on DA receptors in the nigra-striatal dopamine (DA) system. The present study attempted to ascertain its dual action on the mesolimbic DA system. The firing activities of the nucleus accumbens (NAc) neurons were extracellularly recorded with intravenous and iontophoretic administration of the drug in 6-hydroxydopamine (6-OHDA)-lesioned and intact rats. The results showed that SPD produced a consistently biphasic firing of NAc neurons during the cumulative doses of 0.02 2 mg/kg, iv. When the rats were pretreated with D(2) antagonist spiperone, SPD only exerted an increasing effect, which was subsequently reversed by the D(1) antagonist SCH-23390. Moreover, SCH-23390 could prevent the rate of increase elicited by SPD at high doses, presumably due to the D(1) agonistic action of SPD on the activity of NAc neuron. On the other hand, the inhibition of NAc firing elicited by either D(2) agonist LY171555 or D(1)/D(2) agonists apomorphine was completely reversed by SPD, suggesting an antagonistic action of SPD to D(2) receptors. In 6-OHDA-lesioned rats, iontophoresis of SPD also had an inhibitory effect in the majority of NAc neurons (91%) as SKF-38393 did. This inhibition could be completely blocked by the ejection of SCH-23390, but not by spiperone. These results indicate that SPD also has a D(1) agonistic-D(2) antagonistic dual action on NAc neuron activity, which may be beneficial to the treatment of schizophrenia.

Behavioral characteristics of olanzapine: an atypical neuroleptic

AIM

To assess the atypical neuroleptic properties of a novel antipsychotic agent, olanzapine (Ola).

METHODS

The action of Ola on apomorpine (Apo)-induced climbing behavior, 5-hydroxy-dl-tryptophan (5-HTP)-induced head twitch response, oxotremorine-induced tremor, and the conditioned avoidance behavior in mice were observed. The catalepsy of mice induced by Ola was also investigated. The single unit extracellular recording technique was used to compare the spontaneous firing rate changes of dopamine (DA) cells in the ventral tegmental area (VTA, A10) and the substantia nigra pars compact (SNC, A9) in rats after i.v. Ola.

RESULTS

Ola antagonized the climbing behavior (ED50 1.8 mg.kg-1, p.o.), head twitch behavior (ED50 0.3 mg.kg-1, p.o.), and tremor (ED50 5.2 mg.kg-1, p.o.) in mice. In a conditioned avoidance paradigm in mice, Ola inhibited the avoidance response with an ED50 of 2.72 mg.kg-1 (p.o.). However, the catalepsy was not induced by Ola in mice even under a very high dose of 100 mg.kg-1 (p.o.). Ola selectively increased the firing rate of DA cells in the VTA, but failed to affect that of SNC DA cells.

CONCLUSION

Ola distinguished itself from the typical neuroleptic (e.g. haloperidol, Hal) and took resemblance of the atypical neuroleptic (e.g. clozapine, Clo) in 3 aspects: 1) the multiple receptor pharmacodynamics involving D1/D2, 5-HT2 and M-ACh receptors; 2) dose-response separation between the block of conditioned avoidance response and catalepsy induction; and 3) the specificity of action sites of firing rates upon acute drug challenge.

Dopamine-glutamate interaction in rat striatal slices: changes of CCDPK II, PKA, and LDH activity by receptor-mediated mechanisms

AIM

To study the effects of dopamine (DA) and glutamate (Glu) and their receptor agonists/antagonists on Ca2+/calmodulin-dependent protein kinase II (CCDPK II), cyclic AMP-dependent protein kinase A (PKA) activities and the LDH release in rat striatal slices, and to examine the interaction between DA and Glu transmitter systems in striatum.

METHODS

The activities of CCDPK II, PKA, and the release of LDH were determined with the 32P-incorporation and colorimetry respectively in rat striatal slices.

RESULTS

(1) Exogenous DA, D1 receptor agonist SKF 38393 and D2 receptor agonist LY 171555 reduced CCDPK II activity in striatal slices; Glu also inhibited CCPPK II activity in a concentration-dependent manner. NMDA receptor antagonist MK-801 could antagonize the inhibitory effect of SKF 38393 and LY 171555 on the CCDPK II activity. D1 and D2 receptor antagonists SCH 23390 and spiperone could also antagonize the decrease of CCDPK II activity induced by Glu; (2) DA and SKF 38393 markedly increased PKA activity in striatal slices, which was reduced by MK-801; (3) DA and Glu increased the release of LDH from the striatal neurons in a concentration-dependent manner. MK-801 antagonized the increase of LDH induced by DA. Spiperone, rather than SCH 23390, could reduce the release of LDH from striatal neuron in the presence of Glu.

CONCLUSION

The interaction between DA and Glu transmitter systems is found in the regulation of the CCDPK II and PKA activities and cell function in the striatum.

Naphthazarin derivatives (V): formation of glutathione conjugate and cytotoxic activity of 2-or 6-substituted 5,8-dimethoxy-1,4-napthoquinones in the presence of glutathione-S-transferase, in rat liver S-9 fraction and mouse liver perfusate

Formation of glutathione (GSH) conjugates with 2- or 6-(1-hydroxymethyl)- and 2-(1-hydroxyethyl)-DMNQ derivatives (DMNQ, 5,8-dimethoxy-1,4-naphthoquone) was carried out in phosphate buffer (pH 7.4), in the presence of glutathione-S-transferase (GST), in rat liver S-9 fraction and by perfusion, and the rates of conjugates formation were compared and correlated to cytotoxicity. The GSH conjugates of 6-(1-hydroxyalkyl)-DMNQ derivatives were formed faster than 2-(1-hydroxyalkyl)-DMNQ derivatives under all of the media, implying that steric hindrance was the cause of lowering the rate of conjugate formation of 2-substituted derivatives. For both isomers, addition of GST did not improve the reaction rate, compared with that in buffer, while the reaction in the S-9 fraction and the perfusate was accelerated to a great extent. The catalytic effect of the S-9 fraction and the perfusion on 2-isomers was greater than on 6-substituted ones, suggesting that S-9 fraction and the perfusate contain an effective system relaxing the steric hindrance of 2-(1-hydroxyalkyl)-DMNQ derivatives. Furthermore, a good correlation between the formation of the GSH conjugates and the cytotoxic activity of both naphthazarin isomers suggests that the steric hindrance is a cause of lowering the cytotoxicity of 2-isomers.

Effect of the aryl substituent on antitumor activity of 2-substituted-1,4-dihydroxy-9,10-anthraquinones and 2-substituted-anthracene-1,4,9,10-tetraones

2-(1-Aryl-1-hydroxymethyl)- and 2-aroyl-DHAQ derivatives (DHAQ, 1,4-dihydroxy-9,10-anthraquinone), and 2-(1-aryl-1-hydroxymethyl)-ATO derivatives (ATO, anthracene-1,4,9,10-tetraone) were synthesized and their antitumor activities were determined. 2-(1-Aryl-1-hydroxymethyl)-DHAQ derivatives showed a stronger cytotoxicity compared to the series of 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinone derivatives. It was suggested that the presence of aryl group at the side chain accelerated the bioreductive activation leading to cell death. 2-Aroyl-DHAQ derivatives, despite their higher electrophilicity, revealed smaller cytotoxicity and antitumor activity (expressed by T/C value) than 2-(1-aryl-1-hydroxymethyl)-DHAQ derivatives. Thus, no consistent relationship between the electronic effect on aromatic side chain and the cytotoxicity was observed. ATO series exhibited a higher antitumor activity (T/C, 125 to approximately 218%), though their cytotoxicity was not further improved compared to that of 2-(1-aryl-1-hydroxymethyl)-1,4-dihydroxy-9,10-anthraquinones. They manifested no correlation between the cytotoxicity and the antitumor activity. In case of 2-[1-hydroxy-1-(4-propylphenyl)-methyl]-ATO, the most bioactive one in vivo among the same series, it showed an ED50 value of 10.2 mg/mL and a T/C value of 218%. It is assumed that the anthracene-1,4,9,10-tetraones after uptake into cellular tissues might be transformed to a cytotoxic metabolite(s).

Antagonistic effect of l-stepholidine on striatal ischemic injury in rat

AIM

To elucidate the protection of l-stepholidine (SPD) on neuronal morphology and function against the striatal ischemic injury in rat.

METHODS

The forebrain ishemia to Sprague Dawley rats was induced with four-vessel occlusion. Histological examination was performed on the dorsolateral striatum with cresylviolet stain. In striatal slices of rat as an in vitro ischemic model, the activity of calcium/calmodulin-dependent protein kinase II (CCDPK) and lactate dehydrogenase (LDH) was examined by the method of 32P-incorporation and colorimetry, respectively.

RESULTS

In the SPD-treated groups, most of the neurons in the striatum kept the normal morphological appearance after 30-min ischemia followed by 6-h or 12-h reperfusion. The number of neurons was much more in SPD groups than that in vehicle group. The sparse and abnormal neurons were observed in the vehicle group. SPD attenuated the ischemic effect on the CCDPK activity in striatal slices. In addition, SPD inhibited the leakage of LDH from neurons induced by ischemia in incubated striatal slices.

CONCLUSION

SPD protected striatal neurons against ischemic injury and antagonized the inhibitory action on CCDPK activity induced by ischemia. SPD reduced the leakage of LDH from striatal neurons induced by ischemia.

Action sites of rotation and unit firing induced by l-stepholidine and DA agonists in basal ganglia of 6-OHDA-lesioned rats

AIM

To elucidate the action sites of l-stepholidine (SPD) in the basal ganglia.

METHODS

Counting the rotations after intra-nucleus microinjection and recording the neuron firing by microiontophoresis of SPD and DA agonists in the basal ganglia of 6-hydroxydopamine (6-OHDA)-lesioned rats.

RESULTS

The DA immunoreactive substance was markedly reduced in the 6-OHDA-lesioned rats. The intra-neostriatum microinjection of apomorphine (Apo, D1/D2), SK&F 38393 (D1), and SPD elicited remarkable rotation, and the characteristics of SK&F 38393-produced rotation were of long latency and long duration. The intra-substantia nigra pars reticulata (SNR) injection of Apo, SK&F 38393, and SPD induced the rotation response, while the selective D2 agonist quinpirole hydrochloride (Ly171555) did not because of scarce D2 receptors in the SNR. The intraglobus pallidus (GP) injection of DA agonists and SPD failed to evoke rotation, but the GP nucleus still had the contribution to rotation elicited by i.p. injection of DA agonists and SPD in the 6-OHDA-lesioned rats with successive kainic acid (KA) lesion. Besides, the successive lesion of entopeduncular nucleus (EP) on rotation was less important than that of GP nucleus. The microiontophoresis of Apo and SPD into the SNR could evoke the neuron firing, but failed to activate the GP neurons, which were activated by sodium glutamate (Glu) and inhibited by gamma-aminobutyric acid (GABA).

CONCLUSION

The action sites of SPD-induced rotation and neuron firing via the D1 receptors are in the neostriatum and SNR instead of GP. The direct neurocircuit through SNR is the most important for rotation of 6-OHDA-lesioned rats.

Comparison of 12-chloroscoulerine enantiomers on animal behavior to dopamine receptors

AIM

To compare the pharmacological characteristics of 12-chloroscoulerine (CSL) enantiomers to dopamine (DA) receptors.

METHODS

Radioligand receptor binding assay with calf striatum and behavioral tests of mice or rats were used.

RESULTS

In the competitive binding assay, the affinities (Ki) of l-CSL to D1 and D2 receptors were 5.7 nmol.L-1, while those of d-CSL for D1 and D2 receptors were 135 and 9150 nmol.L-1, respectively. The Ki of dl-CSL to D1 and D2 receptors were 8.9 and 9.6 nmol.L-1, respectively, which were slightly weaker than that of l-CSL. In the behavioral experiments, CSL enantiomers 5-60 mg.kg-1 antagonized the stereotypy induced by apomorphine in rats, and 5-150 mg.kg-1 produced catalepsy. The enantiomers 10-60 mg.kg-1 reduced the mice jumping behavior induced by amphetamine + levodopa. l-CSL 10-80 mg.kg-1 antagonized the spontaneous locomotor activity of normal or amphetamine-treated mice.

CONCLUSION

CSL enantiomers are antagonists to DA receptors: l-CSL > dl-CSL >> d-CSL.

Supraspinal D2 receptor involved in antinociception induced by l-tetrahydropalmatine

AIM

To study the role of dopamine (DA) receptors in l-tetrahydropalmatine (l-THP)-induced antinociception.

METHODS

The intraperitoneal (i.p.) and intrathecal (ith) injections were used to give the drugs. The tail-flick test was used to assess the nociceptive threshold of rats.

RESULTS

By i.p. injection, l-THP (10, 20, 40 mg.kg-1) as well as D2 receptor antagonist spiperone (1, 2, 3 mg.kg-1) produced dose-dependent antinociceptive effects on the nociception of rats, while D2 receptor agonist quinpirole, D1 receptor agonist SKF38393, and D1 receptor antagonist Sch-23390 showed no antinociception. Moreover, l-THP- or spiperone-induced antinociception was markedly attenuated by quinpirole (2, 3 mg.kg-1) but not SKF38393 or naloxone. On the other hand, ith quinpirole (20, 30, 40 micrograms.kg-1) also induced a dose-dependent antinociception, while ith l-THP, spiperone, SKF38393, and Sch-23390 did not exhibit any antinociception. Furthermore, ith spiperone (20, 30, 40 micrograms.kg-1) but not Sch-23390 dose-dependently antagonised the antinociception induced by quinpirole. l-THP (ith, 100, 200, 300 micrograms.kg-1) also dramatically attenuated the quinpirole-induced antinociception with a dose-dependent relationship.

CONCLUSION

Activating the spinal D2 receptor or blocking the supraspinal D2 receptor produces antinociception. D1 receptor might be not directly involved in the antinociception. l-THP (as a D2 antagonist) as well as spiperone produces antinociception via blocking the supraspinal D2 receptor.

Glutathione conjugates of 2- or 6-substituted 5,8-dimethoxy-1,4-naphthoquinone derivatives: formation and structure

Thirty-four glutathione conjugates of 5,8-dimethoxy-1,4-naphthoquinones (DMNQ) were synthesized and their structure was determined. The yield of GSH conjugate was dependent on size of alkyl group; the longer the size of alkyl group was, the lower was the yield. It was also found that the length of alkyl side chain influenced the chemical shift of quinonoid protons; the quinonoid protons of 2-glutathionyl DMNQ derivatives with R=H to propyl, 6.51-6.59 ppm vs. other ones with R=butyl to heptyl, 6.64-6.68 ppm. This was explained to be due to a folding effect of longer alkyl group. Glutathione (GSH) reacted with DMNQ derivative first to form a 1,4-adduct (2- or 3-glutathionyl-1,4-dihydroxy-5,8-dimethoxynaphthalenes) and then, the adduct was autooxidized to 2- or 3-glutathionyl-DMNQ derivatives. Moreover, GSH reduced DMNQ derivatives to their hydrogenated products. It was suggested that such an organic reaction might play an important role for a study of metabolism or toxicity of DMNQ derivatives in the living cells.

Effect of tetrahydropalmatine analogs on Fos expression induced by formalin-pain

AIM

To study the effect of tetrahydropalmatine (THP) analogs on Fos protein expression induced by formalin-pain and elucidate analgesic mechanism of THP analogs.

METHODS

The pain response to Sprague Dawley rats was induced with formalin injected s.c. into the plantar surface of the right hindpaw. Fos protein expression in brain and spinal cord was investigated with immunohistochemistry. The numbers of Fos-like immunoreactive (FLI) neurons were counted with Leica Q570 image analyzer.

RESULTS

In the groups of THP analogs and D2 antagonist spiperone, FLI neurons induced by intraperitoneal (i.p.) injection of THP analogs and spiperone were mainly located in the striatum and accumbens nucleus, and a few FLI neurons were also in sensorimotor cortex. In the D1 antagonist, D1 agonist, D2 agonist, saline and vehicle groups, FLI neurons were seldom seen in the striatum and accumbens nucleus. Moreover, the Fos protein expression induced by l-THP and spiperone could be prevented by the pre-treatment of the D2 agonist quinpirole but not D1 agonist SKF38393. In the formalin-pain group, FLI neurons were mainly distributed in ascending pain afferent system (APAS) and descending pain modulation system (DPMS). Following i.p. THP analogs, however, the numbers of FLI neurons induced by formalin-pain in the APAS, such as dorsal horn (mainly laminae I, II, IV-VI) were markedly decreased, while the numbers of FLI neurons in the DPMS, such as periaqueductal gray (PAG) and reticular paragigantocellular lateral nucleus (RPLN) were significantly increased.

CONCLUSION

THP analogs enhanced the activity of brainstem DPMS by the blockade of D2 receptors in the striatum and accumbens nucleus, and sequentially inhibited the inputs of peripheral pain afferent message in spinal cord level.

Increased phosphorylation of DARPP-32 by D1 agonistic action of l-stepholidine in the 6-OHDA-lesioned rat striatum

In order to explore the characteristics of l-stepholidine (SPD) activating the postsynaptic D(1) receptors, the effects of SPD on DARPP-32 phosphorylation in vivo with back-phosphorylation assay and on the postsynaptic D(1) receptor densities with radioligand assay were observed in the striatum of 6-OHDA-lesioned rat. The results showed that following subcutaneously administration of 20 or 40 mg/kg SPD for 21 d, (32)P phosphate incorporation into the DARPP-32 protein in the denervated striatum showed a 50% reduction (P<0.01) vs the intact striatum, indicating an increase of DARPP-32 phosphorylation in vivo in the denervated striatum. However,the D(1) receptor B(max) was decreased from 385.0+/-26.1 to 319.7+/-20.1 fmol/mg protein. It is suggested that D(1) agonist action of SPD decreases the D(1) receptor density but increases the phosphorylation of DARPP-32 in the striatum of 6-OHDA-lesioned rat, which may be responsible for the regulation of D(1) receptor signal transduction in brain neurons.

[Antagonistic effect of tetrahydroproberberine homologues on alpha 1-adrenoceptor]

The antagonistic effect of tetrahydroproberberine (THP) homologues on alpha 1-adrenoceptor was studied by combination of radioligand binding assays and measurements of vasoconstriction responses. The results showed that l-tetrahydropalmatine (l-THP), l-stepholidine (l-SPD), THPB-18 and tetrahydroberberine (THB) competitively inhibited the 125I-BE2254 specific binding in rat cerebral cortex with pK1 values of 5.54 +/- 0.36, 5.56 +/- 0.47, 5.75 +/- 0.56 and 6.01 +/- 0.60, respectively, and the Hill efficiency was not significantly different from unity. They inhibited phenylephrine-induced constrictions with pA2 values of 5.48 +/- 0.58, 5.66 +/- 0.54, 5.64 +/- 0.34 and 5.45 +/- 0.76, respectively, and the slopes of Schild plot were not significantly different from unity. The results indicate that the 4 THP homologues are non-subtype selective competitive antagonists for alpha 1-adrenoceptor with similar affinities.

Anthracene-1,4,9,10-tetraone derivatives: synthesis and antitumor activity

A series of 2-alkylated anthracene-1,4,9,10-tetraone (ATO) derivatives were synthesized, and their antitumor action in ICR mice bearing S-180 cells and antiproliferative activity against L1210 cells were evaluated. Overall, the introduction of an alkyl group (C1-C8) at C-2 enhanced the antiproliferative activity. Among 2-(1-hydroxyalkyl)- or 2-(1-acetoxyalkyl)-ATO derivatives, four compounds possessing alkyl chain of an intermediate size (C4-C6) gave T/C values of > 300%. Acetylation at 1'-OH failed to cause an enhancement in the antitumor action, in contrast to a remarkable increase in antiproliferative activity. Although there was no direct relationship between antiproliferative activity and antitumor action, the compounds with lower antiproliferative activity tended to show higher antitumor activity. Further study shows that the antiproliferative activity of ATO derivatives may be explained properly neither by redox cycling nor arylating capacity.

Comparison of (-)-stepholidine and D1 or D2 agonists on unit firing of globus pallidus in 6-hydroxydopamine-lesioned rats

(-)-Stepholidine(SPD), isolated from the Chinese herb Stephania, is demonstrated to be a DA antagonist, but it also shows D1 agonistic action on rotational behavior in unilateral 6-hydroxydopamine (6-OHDA) lesioned rats. The present study further ascertains its D1 agonistic property on firing activity of globus pallidus (GP) in control and 6-OHDA-lesioned rats. In the control rats, the firing activities of the GP neurons elicited by DA agonists (i.v.), such as apomorphine (D1/D2), SKF38393 (D1), and LY171555 (D2), were readily reversed by SPD (4 mg/kg, i.v.); but SPD, per se, induced variable alterations. In the 6-OHDA-lesioned rats, apomorphine, SKF38393 and LY171555 displayed the marked inhibition as well as excitation on the unit firing. The individual firing variations (87.1+/-17.8, 55.1+/-15.7 and 62.1+/-16.7%, respectively) were much larger than those in the control group, and were completely abolished by SPD (2 mg/kg). However, SPD also showed D1 partial agonistic action on the GP neuron firing. Moreover, the pre-blockade of D2 receptors with spiperone (0.5 mg/kg, i.v.), SPD exhibited the D1 agonist action which was reversed by the D1 antagonist SCH23390. These results suggest that SPD has a dual action on the GP neuron firing in the 6-OHDA-lesioned rats, i.e., antagonist to D2 DA receptors and partial agonist to D1 receptors.

D1/D2 dopamine receptor interaction in membrane abolished by 6-hydroxydopamine lesion

D1/D2 interaction in rat striatum was investigated by examining the effect of the D2 antagonist spiperone on the binding of [3H]SCH23390 to D1 dopamine (DA) receptors. In the presence of endogenous DA, spiperone blocked D2 receptors, then caused the increase of the binding of [3H]SCH23390 in rat striatal homogenate. After the 6-hydroxydopamine (6-OHDA) lesion, the increase was not found even if in the addition of exogenous DA. The results suggest that the D2 antagonist can modify the interaction between endogenous DA and D1 receptors labeled with [3H]SCH23390, while 6-OHDA lesion may change the state of D1/D2 interaction operating at the receptor level.

Involvement of dopamine D1 and D2 receptors in Fos immunoreactivity induced by stepholidine in both intact and denervated striatum of lesioned rats

Stepholidine (SPD), a natural product, has been demonstrated in previous studies as a D1 agonist and D2 antagonist. In this work SPD-induced Fos immunoreactivity was examined. In the normal rats, Fos was induced in the striatum by SPD (1-20 mg/kg, i.p.) dose-dependently. The distribution of Fos-positive cells induced by SPD showed a rostral-caudal decline, matching the distribution of D2 dopamine receptors. The Fos-positive cells were mainly found in striatal neurons retrogradely labeled with horseradish peroxidase (HRP) from GP but not from SN, and could be abolished by the pretreatment of a D2 agonist LY171555 (2 mg/kg, i.p.), suggesting that the Fos expression in normal rats was due to the D2 antagonistic action of SPD. In the unilateral 6-hydroxydopamine-lesioned rats, SPD (4 mg/kg, i.p.) induced Fos expression in intact and denervated side of the striatum with different characteristics. Similar to that of normal rats, the Fos expression in intact side possessed the rostral-caudal gradient and could be abolished by the pretreatment of LY171555. However, in the denervated side, the Fos positive cells were widely distributed, and mainly found in striatal neurons retrogradely labeled from SN but not from GP. Furthermore, this expression was prevented by the pretreatment of SCH23390 (0.2 mg/kg, i.p.) but not LY171555, suggesting that the Fos expression in denervated side was due to the D1 agonistic action of SPD. Therefore, we concluded that the Fos expression induced by SPD in intact and denervated striatum was mediated via D2 and D1 receptor respectively, supporting the previous standpoint that SPD possesses the dual action, i.e antagonist to D2 and agonist to D1 receptors. Furthermore, it is suggested that the contralateral turning behavior induced by SPD may result from the D1-mediated excitation of striatonigral neurons of the denervated side of the lesioned rats.

2-(1-Oxyalkyl)-1,4-dioxy-9,10-anthraquinones: synthesis and evaluation of antitumor activity

Fourty eight derivatives of 2-(1-oxyalkyl)-1,4-dioxy-9,10-anthraquinone were synthesized, and their antitumor activity was evaluated. On the whole, 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinones (DHAQ = 1,4-dihydroxy-9,10-anthraquinone) showed stronger cytotoxic activity against L1210 cells than 2-(1-hydroxyalkyl)-1,4-dimethoxy-9,10-anthraquinones(DMAQ = 1,4-dimethoxy-9,10-anthraquinone), implying that free hydroxy groups at C-1 and C-4 of the anthraquinone structure are necessary for the cytotoxic activity. The bioactivity of 2-(1-hydroxyalkyl)-DHAQ derivatives differed according to the size of alkyl group at C-1; while the elongation of alkyl group over 7 carbon atoms failed to enhance the bioactivity, the derivatives possessing alkyl moiety of 1-6 carbon atoms showed an increase in the cytotoxicity and the antitumor activity in Sarcoma-180; 2-hydroxymethyl-DHAQ (ED50, 15 micrograms/ml; T/C, 125%), 2-(1-hydroxyethyl)-DHAQ(1.9 micrograms/ml; 139.2%), 2-(1-hydroxypropyl)-DHAQ (7.2 micrograms/ml; 135.1%), 2-(1-hydroxybutyl)-DHAQ (10.2 micrograms/ml; 125.3%), 2-(1-hydroxypentyl)-DHAQ (23.7 micrograms/ml; 110.1%), and 2-(1-hydroxyhexyl)-DHAQ (58 micrograms/ml; 108%). Next, 2-(1-Hydroxyalkyl)-DHAQ derivatives were acetylated to produce 2-(1-acetoxyalkyl)-DHAQ analogues. Although the acetylation somewhat enhanced the cytotoxicity, but not the antitumor action. In addition, the presence of phenyl group at C-1' enhanced the cytotoxicity and the T/C value, compared to alkyl groups of same size; 2-(1-hydroxy-1-phenyl)-DHAQ (ED50, 5.6 micrograms/ml; T/C, 137%).

Enhancement of (-)-stepholidine on protein phosphorylation of a dopamine- and cAMP-regulated phosphoprotein in denervated striatum of oxidopamine-lesioned rats

AIM

To study effects of (-)-stepholidine (SPD) on the phosphorylation of a dopamine- and cAMP-regulated phosphoprotein (DARPP-32) in the striatum of oxidopamine-lesioned rats.

METHODS

The amount of dephospho-DARPP-32 was measured by a back-phosphorylation assay.

RESULTS

In the striatum of control rats, SPD per se had no effect on the phosphorylation of DARPP-32, but it antagonized the decrease by 28% of dephospho-DARPP-32 induced by the D1 agonist SK&F-38393. In the denervated striatum of oxidopamine-lesioned rats, SPD decreased the amount of dephospho-DARPP-32 by 44%. The effect of SPD was completely counteracted by the concomitant administration of the D1 antagonist Sch-23390.

CONCLUSION

SPD exhibits D1 agonistic action on DARPP-32 phosphorylation in the denervated striatum of oxidopamine-lesioned rats, but it acts as a D1 antagonist in normal striatum.

Tetrahydroberberine blocks membrane K+ channels underlying its inhibition of intracellular message-mediated outward currents in acutely dissociated CA1 neurons from rat hippocampus

In the patch-clamp perforated whole-cell recording mode, tetrahydroberberine (THB), a novel dopamine (DA) receptor antagonist, inhibits not only DA-induced outward K+ currents, but also acetylcholine-, caffeine- or strychnine-induced outward current. However, THB does not affect either GABA- or glycine-induced Cl- currents, or non-NMDA receptor agonist-induced cation currents. As expected for a K+ channel blocker, THB evokes a downward current deflection accompanied by a decrease of conductance. It is concluded that the direct blockade of membrane K+ channels by THB underlies its inhibition of intracellular message-mediated outward currents.

Involvement of receptor reserve in D1 agonistic action of (-)-stepholidine in lesioned rats

(-)-Stepholidine (SPD) is a natural product. Previous studies had demonstrated that SPD displayed D1 agonism in unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats and D1 antagonism in reserpinized rats and normal rats. The aim of the present study was to explain this peculiar pharmacological action based on behavioral and biochemical experiments. In the unilaterally 6-OHDA-lesioned rats, SPD (4 mg/kg, s.c.) induced contralateral rotation as did apomorphine (APO), but the rotation response to SPD was 60% lower than that to APO (0.5 mg/kg, i.p.). Coadministration with APO (0.5 mg/kg, i.p.) and SPD (0.5 to 10 mg/kg, s.c.) produced a biphasic action curve. At low doses (0.5 or 1 mg/kg), SPD potentiated APO action; at high doses (4 or 10 mg/kg), however, SPD suppressed APO. In striatal homogenate of the unilaterally lesioned rats, SPD stimulated cyclic AMP (cAMP) formation and produced a maximal response comparable to that of dopamine (DA) in the denervated striatum, but 70% lower than that of DA in the intact striatum. Coadministration of 10 microM DA with various concentrations of SPD yielded different results, with a biphasic response in the intact side and a synergistic effect in the denervated side. Furthermore, based on the determination of receptor-mediated cAMP formation, the D1 receptor reserve was analyzed in both denervated and intact striatum by using the DA receptor inactivator N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). The results showed that following EEDQ administration, the receptor density [revealed by [3H]R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-be nzazepine ([3H]SCH-23390) binding] and the agonist-stimulated adenylate cyclase (AC) activity (revealed by cAMP formation) were reduced concurrently. In the intact striatum, the reduction in SPD-stimulated AC activity paralleled the receptor loss, indicating the absence of receptor reserve, while in the denervated striatum the reduction in AC activity was less than the receptor loss, indicating a significant level of receptor reserve (estimated 16.4%). By comparison, receptor reserve for DA was 45.7 and 25.3% in the denervated and intact striatum, respectively, representing an 80% increase of receptor reserve. In conclusion, SPD is a D1 partial agonist, and receptor reserve permits SPD to display its D1 agonistic action in the unilaterally 6-OHDA-lesioned rats.

GTP regulation of (-)-stepholidine binding to R(H) of D1 dopamine receptors in calf striatum

(-)-Stepholidine (SPD) exhibits antagonist effects on normosensitive dopamine (DA) receptors, but it has an agonist action on rotation in unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats. The present work endeavors to further elucidate the mechanism of its agonist action on D1 receptors. [3H]R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-be nzazepine ([3H]SCH-23390) and [3H]spiperone were used, respectively, as radioligands in D1 and D2 DA receptor binding assays in calf striatal membranes. Experimental data were analyzed by a non-linear regression computer program, GraphPAD InPlot 3.15. The competition curves were fitted first by a single-site equation and then by a two-site equation. The results showed that both apomorphine (APO) and SPD competitively inhibited [3H]SCH-23390 binding. Their competition curves fitted best to the two-site equation (P < 0.05) with a high-affinity site (R(H)) and a low-affinity site (R(L)) to DA receptors. The K(H) and K(L) values (nM) were 2.7 +/- 0.45 and 378 +/- 62 for APO, and 3.9 +/- 2.2 and 126 +/- 25 for SPD, respectively. In contrast, the competition curve of SCH-23390, a selective D1 DA receptor antagonist, fitted best to a single-site model with a Ki value of 1.7 +/- 0.5 nM. The R(H) of APO or SPD could be decreased by the addition of 450 microM GTP. In the [3H]spiperone binding test, the APO curve was modeled best by the two-site equation, while the SPD curve fitted best to a single-site model. In the rotational behavior test, APO induced 441 +/- 20 turns/30 min in the 6-OHDA-lesioned rats, and SPD induced 310 +/- 42 turns/30 min, while SCH-23390 antagonized the SPD-induced rotation but did not induce rotational behavior. These results suggest that SPD possesses agonist actions on D1 but antagonist effects on D2 DA receptors.

Characteristics of tetrahydroprotoberberines on dopamine D1 and D2 receptors in calf striatum

AIM

To study the characteristics of tetrahydroprotoberberines (THPB) on dopamine D1 and D2 receptors and elucidate their structure-activity relationship.

METHODS

Radioligand assay in vitro with a two-site model program analysis.

RESULTS

Four THPB with two hydorxyl groups on C2 and C9 or C2 and C10 exhibited RH and RL two binding sites to D1 receptors and guanosine triphosphate regulated the RH binding site of SPD and THPB-132A in competition assay, while eleven THPB including nonhydroxy-THPB, monohydroxy-THPB, and THPB with two hydroxyl groups attaching to C3 and C10 showed one binding site to D1 receptors under the same conditions. However, the tested eleven THPB all manifested one binding site to D2 receptors in competition assay, and the 2-hydroxy-THPB had the most potent affinity for D2 receptors.

CONCLUSION

Dihydroxy-THPB with two hydroxyl groups attaching to C2 and C9 or C2 and C10 possess the intrinsic activity of agonist to D1 receptors, while the other THPB do not. The tested eleven THPB all are the antagonists of D2 receptors.

Effects of tetrahydroprotoberberines on dopamine D2 receptors in ventral tegmental area of rat

AIM

To compare the actions of tetrahydroprotoberberines (THPB) on dopamine (DA) D2 receptors in the ventral tegmental area (VTA) of rat.

METHODS

Extracellular single unit recording technique was used in i.v. gallamine-paralyzed rats.

RESULTS

Eleven THPB analogs tested completely attenuated the apomorphine (Apo, 20 micrograms.kg-1)-induced inhibition on VTA DA cell firing activity. The OH group on C2 at THPB was linked with the reversal of Apo-induced inhibition. Their reversal potencies (ED50, microgram.kg-1) for D2 receptors were: THPB-143 (5.6) > SPD (8.5) > Iso (17.0) > THP (33) > THB (48) > THPB-18 (66) > THPB-1 (179) > THPB-19 (408) > THPB-126 (510) > THPB-104 (1019) > THPB-10 (4815).

CONCLUSION

Among these 11 THPB, the 2-hydroxyl-THPB (THPB-143) showed the strongest antagonistic action on D2 receptors.

Tetrahydroberberine inhibits acetylcholine-induced K+ current in acutely dissociated rat hippocampal CA1 pyramidal neurons

The effects of a novel chemical type of dopamine receptor antagonist, the tetrahydroprotoberberine analogs (THPBs), on acetylcholine (ACh)-induced current were studied in freshly dissociated pyramidal neurons from rat hippocampal CA1 area using the nystatin perforated patch-clamp recording technique. Under voltage clamp conditions, the ACh-induced outward current (IACh) is sensitive to the muscarinic receptor antagonist, atropine and the K+ channel blocker, TEA. The reversal potential of IACh (-84.1 +/- 0.8 mV) is close to the K+ equilibrium potential, indicating that the IACh is mediated by a muscarinic receptor, and is carried mainly by K+. Tetrahydroberberine (THB) markedly reduced the IACh while its chemical analogs, l-stepholidine (l-SPD) or l-tetrahydropalmatine (l-THP), had little effect on the IACh. The half-maximal inhibitory concentration (IC50) of THB was 1.3 x 10(-5) M for a 10(-5) M ACh-induced IACh. THB suppressed the maximum of the ACh concentration-response curve without shifting the Hill coefficient, indicating a non-competitive inhibition. It is concluded that THB non-competitively inhibits the ACh-induced K+ current in a concentration-dependent manner, and that this inhibitory effect provides further evidence that THB plays its pharmacological roles in the central nervous system by effects other than through blockade of dopamine receptors.

(-)-Stepholidine enhances K+ depolarization-induced activation of synaptosomal tyrosine 3-monooxygenase from rat striatum

AIM

To study the mechanism of K+ depolarization-induced activation of synaptosomal tyrosine 3-monooxygenase (TM) in rat striatum and the effect of (-)-stepholidine (SPD) on this activation.

METHODS

The TM was assayed for DOPA by HPLC-ECD; the activities of Ca2+/calmodulin (CaM)-dependent protein kinase (PK II) and Ca2+/phosphoinositide-dependent protein kinase (PKC) were assayed using histidine as substrate.

RESULTS

The incubation of striatal synaptosomes in K(+)-riched (60 mmol.L-1) medium resulted in a marked activation of TM. PKC inhibitor polymyxin B (PMB) completely blocked the activation of K+ 60 mmol.L-1 on TM. Selective D2 receptor agonist quinpirole (QP), Ca2+ removal from incubation medium and CaM antagonist W7 failed to affect the activation. However, SPD enhanced the activation of K+ 60 mmol.L-1 on TM. Meanwhile, the incubation in K+ 60 mmol.L-1 also activated PKC. Neither QP nor SPD affected K+ depolarization-induced activation of PKC.

CONCLUSION

The activation of K+ depolarization on synaptosomal TM is enhanced by SPD and this activation is mediated by PKC rather than by PK II.

Dual actions of (-)-stepholidine on the dopamine receptor-mediated adenylate cyclase activity in rat corpus striatum

(-)-Stepholidine (SPD) is an antagonist of normosensitive dopamine (DA) receptors, but it exhibits D1 agonistic action on rotational behaviour in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra pars compacta (SNC). In the present study, agonistic and antagonistic effects of SPD on the DA receptor-mediated synaptosomal adenylate cyclase (AC) activity in rat striatum were investigated. After blockade of D2 receptors, SPD augmented AC activity dose-dependently. The EC50 value was 41.1 +/- 8.6 micromol/L. At the concentration of 10 micromol/L, SPD increased cAMP formation from a basal level (50.8 +/- 10.3 pmol/mg protein/min) to 133.7 +/- 31.8 pmol/mg protein/min. The SPD-induced stimulation of AC activity was almost completely reversed by 10 micromol/L Sch23390. These results indicate that SPD possesses an agonistic action on the D1 receptor. Forskolin-stimulated adenylate cyclase (FSAC) activity was used as a model to elucidate the effect of SPD on D2 receptors. The results indicate that DA inhibited FSAC activity dose-dependently, while SPD partially restored FSAC activity. Taken together, these results support the conclusion that SPD has dual actions on DA receptors that mediate AC activity, i.e., an agonistic action on D1 receptors and an antagonistic action on D2 receptors.

Chronic treatment with (-)-stepholidine alters density and turnover of D1 and D2 receptors in striatum

AIM

To study the effects of chronic administration of SPD on the density and turnover of striatal D1 and D2 dopamine (DA) receptors.

METHODS

Receptor density was monitored by radio-receptor binding assay. The receptor recovery and turnover were studied after irreversible inactivation by N-ethoxycarbonyl-2-ethoxy-1, 2-dihydro-quinoline (EEDQ).

RESULTS

Chronic SPD treatment (sc, 20 mg.kg-1.d-1 x 21 d) upregulated both striatal D1 and D2 receptor density. As compared to vehicle-treated rats, SPD increased D1 and D2 receptors by 41.5% and 43.7%, respectively SPD also altered the turnover of both D1 and D2 receptors. The degradation rate constant (k = 0.0082.h-1) and the synthesis rate (r = 2.65 pmol.h-1/g protein) of D2 receptors in SPD-treated rats were significantly increased vs vehicle-treated rats (k = 0.0049.h-1; r = 1.10 pmol.h-1/g protein). The degradation rate constant (k = 0.0059.h-1) and the synthesis rate (r = 3.1 pmol.h-1/g protein) of D1 receptors was also increased in SPD-treated rats vs vehicle-treated rats (k = 0.0048.h-1; r = 1.8 pmol.h-1/g protein), but the alteration of degradation rate constant missed significance (P > 0.05). As a result, receptor recovery following EEDQ was accelerated. The half time for D1 and D2 receptors recovery in SPD group were 117.5 h and 84.5 h, respectively, shorter than 144.4 h and 141.4 h in vehicle-treated rats.

CONCLUSION

Chronic SPD treatment upregulated D1 and D2 receptors, and accelerated DA receptor turnover and recovery mainly by increasing receptor synthesis.

D1 dopamine receptor stimulation inhibits firing activity of midbrain dopamine neurons in reserpine treated rats: an effect eliminated after hemitransection of diencephalon

It has been reported that systemic administration of the D1 dopamine (DA) receptor agonist SKF 38393 inhibits the firing rate of substantia nigra pars compacta (SNC, A9) DA neurons after repeated reserpine treatment in locally anesthetized rats, although SKF 38393 induces little effect on the firing of midbrain DA neurons in normal rats. The present study found that local pressure microejection of SKF 38393 (10(-2) M, 20-100 nl) to SNC or substantia nigra pars reticulata (SNR) failed to influence the firing of SNC DA neurons in reserpinized rats (reserpine 1 mg/kg x 6 days, s.c.); subsequent intravenous (i.v.) injection of SKF 38393 (4 mg/kg), however, inhibited their firing and the inhibition was reversed by the D1 receptor antagonist SCH 23390. Similarly, systemic administration of SKF 38393 (4 mg/kg, i.v.) inhibited the firing of ventral tegmental area (VTA, A10) DA cells in reserpinized rats, while local microejection of SKF 38393 (10(-2) M, 30-60 nl) did not affect their firing. Furthermore, the inhibitory effect of systemic SKF 38393 on firing rate of either SNC or VTA DA neurons in reserpinized rats was eliminated after hemitransection of diencephalon. These results suggest that repeated reserpine treatment renders midbrain DA neurons responsive to D1 receptor stimulation and that D1 receptor agonist-induced inhibition of midbrain DA cell firing in reserpinized rats may require the involvement of long-loop feedback pathways.

Effect of (-)-stepholidine on serum prolactin level of female rats

AIM

To study the effect of (-)-stepholidine (SPD) on serum prolactin (PRL) level and elucidate its pharmacological action on dopamine D2 receptors.

METHOD

After i.p. administration of dopamine receptor agonist, antagonist, or SPD, the serum PRL levels were determined by radioimmunoassay.

RESULTS

SPD (24 mg.kg-1, i.p.) caused a rapid rise in serum PRL level, lasting more than 1 h. SPD 0.2-40 mg.kg-1 raised serum PRL level in a dose-dependent manner with ED50 of 3.7 mg.kg-1 (95% confidence limits, 2.6-4.3 mg.kg-1) and PRL maximal level of 448 +/- 64 micrograms.L-1. Pergolide 2 mg.kg-1 i.p. caused a decrease (P < 0.01 vs saline) of PRL level, which was partially attenuated by SPD of 5 mg.kg-1 and completely abolished by 10 mg.kg-1.

CONCLUSION

SPD is a dopamine D2 receptor antagonist.

[Antagonism of l-stepholidine against bromocriptine-inhibition on prolactin level in lactational rats]

AIM

To study the antagonism of l-stepholidine (SPD) against bromocriptine (Bro)-inhibition on prolactin (PRL) level.

METHODS

Bro (0.5 mg.kg-1.d-1, s.c.) reduced the PRL and caused a dysplasia of mammary gland in lactational rats. The weight growing of newborn rats was retarded. The PRL of the lactational rats was assessed by immunoradiometric assay (IRMA); the weight of newborn rats and development of mammary glands in lactational rats were also examined. Antagonism of SPD was evaluated.

RESULTS

SPD (30 & 100 mg.kg-1.d-1, i.p.) obviously antagonized the Bro that induced lowering the PRL level in lactational rats, the PRL was 11 +/- 4 & 23 +/- 6 micrograms.L-1 (NS 7 +/- 2) respectively on d 15 of postpartum and the development of mammary gland in lactational rats was normal. The newborn rats grew rapidly in 11-15 d.

CONCLUSION

SPD possessed an antagonism with Bro inhibition on D2 receptors located in the pituitary gland, and was an antagonist of dopamine D2 receptors.

(-)-Stepholidine acts as a D1 partial agonist on firing activity of substantia nigra pars reticulata neurons in 6-hydroxydopamine-lesioned rats

(-)-Stepholidine (SPD), a novel dopamine (DA) D1 and/or D2 receptor antagonist in normosensitive animals, shows agonistic effects on D1 receptors in rotational behavior of 6-hydroxydopamine (6-OHDA)-lesioned rats. To further characterize the pharmacological properties of SPD, we investigated the effects of SPD on firing activity of substantia nigra pars reticulata (SNR) neurons in different sensitive models. In control rats, the selective D1 agonist SKF38393 (4 mg/kg, i.v.) induced inconsistent changes (i.e. increase, decrease or no change) in firing of SNR neurons. These effects were completely antagonized by SPD (i.v.), regardless of the changes induced by SKF38393. SPD (4 mg/kg), per se, increased firing by 30.9 +/- 14.4%. In reserpinized rats, SKF38393 also induced SPD-reversible inconsistent changes as in control rats. Nevertheless, SPD per se produced no alteration in firing of SNR neurons. In 6-OHDA-lesioned rats, 5/6 SNR neurons were inhibited by SKF38393. The inhibition was completely abolished by Sch23390, a selective D1 antagonist (0.5-2 mg/kg), but partially reversed by SPD (1-16 mg/kg). Moreover, SPD (4 mg/kg) itself caused SNR increased or decreased neuron firing, and these effects were completely reversed by Sch23390 (0.5-2 mg/kg) in 8/12 neurons recorded. These results suggest that SPD acts as a partial agonist to D1 receptors in 6-OHDA-lesioned rats, but as an antagonist to D1 receptors in normal and reserpinized rats.