BACKGROUNDTo evaluate whether serotonin (5-HT), 5-HT2A receptor (5-HT2AR), and 5-HT transporter (serotonin transporter [SERT]) are associated with different disease states of depression, myocardial infarction (MI) and MI co-exist with depression in Sprague-Dawley rats.

METHODSAfter established the animal model of four groups include control, depression, MI and MI with depression, we measured 5-HT, 5-HT2AR and SERT from serum and platelet lysate.

RESULTSThe serum concentration of 5-HT in depression rats decreased significantly compared with the control group (303.25 ± 9.99 vs. 352.98 ± 13.73; P = 0.000), while that in MI group increased (381.78 ± 14.17 vs. 352.98 ± 13.73; P = 0.000). However, the depression + MI group had no change compared with control group (360.62 ± 11.40 vs. 352.98 ± 13.73; P = 0.036). The changes of the platelet concentration of 5-HT in the depression, MI, and depression + MI group were different from that of serum. The levels of 5-HT in above three groups were lower than that in the control group (380.40 ± 17.90, 387.75 ± 22.28, 246.40 ± 18.99 vs. 500.29 ± 20.91; P = 0.000). The platelet lysate concentration of 5-HT2AR increased in depression group, MI group, and depression + MI group compared with the control group (370.75 ± 14.75, 393.47 ± 15.73, 446.66 ± 18.86 vs. 273.66 ± 16.90; P = 0.000). The serum and platelet concentration of SERT in the depression group, MI group and depression + MI group were all increased compared with the control group (527.51 ± 28.32, 602.02 ± 23.32, 734.76 ± 29.59 vs. 490.56 ± 16.90; P = 0.047, P = 0.000, P = 0.000 in each and 906.38 ± 51.84, 897.33 ± 60.34, 1030.17 ± 58.73 vs. 708.62 ± 51.15; P = 0.000 in each).

CONCLUSIONSThe concentration of 5-HT2AR in platelet lysate and SERT in serum and platelet may be involved in the pathway of MI with depression. Further studies should examine whether elevated 5-HT2AR and SERT may contribute to the biomarker in MI patients with depression.

Animals ; Depression ; metabolism ; Enzyme-Linked Immunosorbent Assay ; Male ; Myocardial Infarction ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT2A ; metabolism ; Serotonin ; metabolism ; Serotonin Plasma Membrane Transport Proteins ; metabolism

OBJECTIVETo explore the effect of 5-HT2A-receptors coupled with superoxide anion (O2-) on respiratory regulation signal transductionin passageway in the medial area of nucleus retrofacialis (mNRF).

METHODSmNRF island was prepared from medullary slices of neonatal SD rats according to Johnson's method and transferred separately into 24-well culture plates with reagents according to protocol, followed by incubation for 60 min at 37 degrees C in a humidified incubator with 5% CO2. Absorbance of 100 microl supernatant was measured by spectrophotometry at 550 nm and the effect of 5-HT and 2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI, agonist of 5-HT2A-receptors) on O2- generation in the mNRF was observed, along with the inhibition of this effect by ketanserin (antagonist of 5-HT2A-receptors) and alpha-lipoic acid (alpha-LA, a antioxidant).

RESULTS5-HT concentration-response curve demonstrated that absorbance peak occurred at 1 micromol/L without further increment with higher concentration. DOI concentration-response curve showed the absorbance peak at 20 micromol/L without further increment. 5-HT and DOI significantly increased the absorbance with comparable effects. Ketanserin and alpha-LA significantly decreased the absorbance generated by 5-HT and DOI.

CONCLUSIONActivation of 5-HT2A receptors results in obvious O2- production in mNRF, suggesting that 5-HT2A receptors regulate respiratory function in association with O2-.

Animals ; Animals, Newborn ; Medulla Oblongata ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT2A ; metabolism ; physiology ; Respiratory Center ; metabolism ; physiology ; Superoxides ; metabolism

To investigate the effects of nikethamide on the generation and modulation of rhythmic respiration of neonatal rats and the role of 5-HT(2A) receptor in this course, experiments were performed on the transverse medullary slices of neonatal rats (both sexes, 1-3 d) in vitro. The slices containing the medial region of the nucleus retrofacialis (mNRF) with the hypoglossal nerve rootlets were prepared in which the respiratory-related rhythmic discharge activity (RRDA) was recorded from the hypoglossal nerve rootlets by suction electrode. The possible role of nikethamide on RRDA was investigated by administration of an agonist of 5-HT(2A) receptor, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), and an antagonist of 5-HT(2A) receptor, ketanserine, dissolved in modified Krebos solution (MKS). Thirty slices were randomly divided into five groups: Group 1: the slices were perfused with different concentrations of nikethamide (0.5, 1, 3, 5, 7, 10 μg/mL), and the most effective concentration was selected; Group 2: the slices were perfused with DOI (40 μmol/L); Group 3: the slices were perfused with ketanserine (40 μmol/L); Group 4: the slices were perfused with ketanserine + DOI; Group 5: the slices were perfused with nikethamide, then perfused with nikethamide + ketanserine after washout of nikethamide. Nikethamide increased RRDA in transverse medullary slices at 0.5-7 μg/mL, and 5 μg/mL was the most effective concentration. DOI increased RRDA with prolonged inspiratory time (TI), increased integral amplitude (IA), and shortened respiratory cycle (RC). Ketanserine decreased RRDA with shortened TI, decreased IA and prolonged RC. Ketanserine + DOI had no significant effects on RRDA. The effects of nikethamide on RC and IA were totally and partially reversed by additional application of ketanserine, but the effect of nikethamide on TI was not influenced by ketanserine. It is proposed that nikethamide increases RRDA partly via 5-HT(2A) receptors.
Animals ; Animals, Newborn ; Female ; In Vitro Techniques ; Male ; Medulla Oblongata ; drug effects ; physiology ; Nikethamide ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT2A ; metabolism ; Respiration ; drug effects ; Respiratory Center ; physiology ; Serotonin

5-hydroxytryptamine (5-HT) released in inflammatory tissues plays a pivotal role in pain hypersensitivity. However, it is not clear whether 5-HT2A receptors in the inflamed tissues mediate this effect. The present study investigated the contribution of 5-HT2A receptors in the periphery to chronic inflammatory pain. Complete Freund's adjuvant (CFA) was injected subcutaneously in the hindpaw of rats. The selective 5-HT2A receptor antagonist ketanserin was given in the inflamed site. Paw withdrawal latency responding to heat or mechanical stimuli was measured. Expression of neuropeptide Y (NPY) in the spinal dorsal horn and dorsal root ganglia (DRG) was assayed using immunohistochemistry technique. The results showed that ketanserin administered in the inflamed site inhibited thermal hyperalgesia in a dose-dependent manner (20, 40 and 80 µg) induced by the intraplantar injection of CFA. Ketanserin given once per day at a dose of 80 µg abolished heat hyperalgesia and also attenuated mechanical allodynia on the third day. CFA injection increased the expression of NPY in superficial laminae of the spinal cord, but not in the DRG. The local treatment of ketanserin completely inhibited CFA-induced increase in NPY expression in superficial laminae of the spinal cord. These results indicated that activation of 5-HT2A receptors in the inflamed tissues was involved in the pathogenesis of inflammatory pain and the blockade of 5-HT2A receptors in the periphery could relieve pain hypersensitivity and normalize the cellular disorder in the spinal dorsal horn associated with pathological pain. The present study suggests that the peripheral 5-HT2A receptors can be a promising target for pharmaceutical therapy to treat chronic inflammatory pain without central nervous system side effects.
Animals ; Freund's Adjuvant ; adverse effects ; Ganglia, Spinal ; metabolism ; Hot Temperature ; Hyperalgesia ; chemically induced ; drug therapy ; Inflammation ; drug therapy ; Ketanserin ; pharmacology ; Neuropeptide Y ; metabolism ; Pain ; drug therapy ; Pain Measurement ; Rats ; Receptor, Serotonin, 5-HT2A ; metabolism ; Serotonin ; Serotonin 5-HT2 Receptor Antagonists ; pharmacology ; Spinal Cord Dorsal Horn ; metabolism

OBJECTIVETo observe the effects of Tangweian granule on 5-HT(2A)R in rat model with diabetic gastroparesis (DGP).

METHODThe rats with diabetic gastroparesis induced by injecting alloxan and giving 200% Radix Rehmanniae preparata were divided into four groups randomly: Tangweian high dosage group, Tangweian low dosage group, motilium control group and the model control group, 10 rats each group. Each group was irrigated with drugs during establishing the model. Additionally, we chose 10 rats by way of normal control group. Further more, Tangweian high dosage group were irrigated stomach with gliclazide 20 mg x kg(-1) and Tangweian granule 31.75 g x kg(-1); Tangweian low dosage group were irrigated stomach with gliclazide 20 mg x kg(-1) and Tangweian granule 15.88 g x kg(-1); motilium control group were irrigated stomach with gliclazide 20 mg x kg(-1) and motilium 3.75 mg x kg(-1) and the model control group were irrigated stomach with distilled water. Then the effects of Tangweian granule on 5-HT(2A)R were observed.

RESULTThe curative group had better effects than the control group in lowering the blood sugar and the level of 5-HT(2A)R content (P < 0.01). And there was significant difference between the curative group and control group (P < 0.05).

CONCLUSIONIt is verified that Tangweian granule has obvious effects on lowering the blood sugar and improving the level of 5-HT(2A)R.

Animals ; Blood Glucose ; drug effects ; Diabetes Mellitus, Experimental ; complications ; metabolism ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Gastroparesis ; drug therapy ; metabolism ; Gliclazide ; pharmacology ; Male ; Random Allocation ; Rats ; Rats, Wistar ; Receptor, Serotonin, 5-HT2A ; metabolism

Serotonin (5-hydroxytryptamine (5-HT)) is a neurotransmitter that regulates a variety of functions in the nervous, gastrointestinal and cardiovascular systems. Despite such importance, 5-HT signaling pathways are not entirely clear. We demonstrated previously that 4-aminopyridine (4-AP)-sensitive voltage-gated K+ (Kv) channels determine the resting membrane potential of arterial smooth muscle cells and that the Kv channels are inhibited by 5-HT, which depolarizes the membranes. Therefore, we hypothesized that 5-HT contracts arteries by inhibiting Kv channels. Here we studied 5-HT signaling and the detailed role of Kv currents in rat mesenteric arteries using patch-clamp and isometric tension measurements. Our data showed that inhibiting 4-AP-sensitive Kv channels contracted arterial rings, whereas inhibiting Ca2+-activated K+, inward rectifier K+ and ATP-sensitive K+ channels had little effect on arterial contraction, indicating a central role of Kv channels in the regulation of resting arterial tone. 5-HT-induced arterial contraction decreased significantly in the presence of high KCl or the voltage-gated Ca2+ channel (VGCC) inhibitor nifedipine, indicating that membrane depolarization and the consequent activation of VGCCs mediate the 5-HT-induced vasoconstriction. The effects of 5-HT on Kv currents and arterial contraction were markedly prevented by the 5-HT2A receptor antagonists ketanserin and spiperone. Consistently, alpha-methyl 5-HT, a 5-HT2 receptor agonist, mimicked the 5-HT action on Kv channels. Pretreatment with a Src tyrosine kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine, prevented both the 5-HT-mediated vasoconstriction and Kv current inhibition. Our data suggest that 4-AP-sensitive Kv channels are the primary regulator of the resting tone in rat mesenteric arteries. 5-HT constricts the arteries by inhibiting Kv channels via the 5-HT2A receptor and Src tyrosine kinase pathway.
4-Aminopyridine/pharmacology ; Action Potentials ; Animals ; Calcium Channel Blockers/pharmacology ; Calcium Channels/metabolism ; Cells, Cultured ; Ketanserin/pharmacology ; Male ; Mesenteric Arteries/drug effects/*metabolism/physiology ; Muscle Contraction ; Muscle, Smooth, Vascular/cytology/drug effects/metabolism/physiology ; Myocytes, Smooth Muscle/drug effects/metabolism/physiology ; Nifedipine/pharmacology ; Potassium Channel Blockers/pharmacology ; Potassium Channels, Voltage-Gated/antagonists & inhibitors/*metabolism ; Protein Kinase Inhibitors/pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT2A/*metabolism ; Serotonin/*pharmacology ; Serotonin 5-HT2 Receptor Antagonists/pharmacology ; Spiperone/pharmacology ; *Vasoconstriction ; src-Family Kinases/antagonists & inhibitors/*metabolism