Neuropeptides
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The role of oxytocin (OXT) in pain modulation has been suggested. Indeed, hypothalamic paraventricular nuclei (PVN) electrical stimuli reduce the nociceptive neuronal activity (i.e., neuronal discharge associated with activation of Aδ- and C-fibers) of the spinal dorsal horn wide dynamic range (WDR) cells and nociceptive behavior. Furthermore, raphe magnus nuclei lesion reduces the PVN-induced antinociception, suggesting a functional interaction between the OXT and the serotoninergic system. ⋯ Similar results were obtained with PVN stimulation plus 5-HT (5×10-5nmol). In WDR cell recordings, the PVN-induced antinociception was enhanced by i.t. 5-HT and partly blocked when the spinal cord was pre-treated with methiothepin (80nmol). Taken together, these results suggest that serotonergic mechanisms at the spinal cord level are partly involved in the OXT-induced antinociception.
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Previously, we demonstrated that maternal prolactin inhibition at the end of lactation, using bromocriptine (BRO), leads to an increase in leptin transfer via milk and induces the adult progeny to present hypothyroidism, leptin resistance and metabolic syndrome (obesity, hyperglycemia, hypertriglyceridemia, lower HDL). To test if these alterations are due to direct BRO action on the pups, in the present study we evaluated the long-term effects of direct injection of BRO (0.1μg/once daily) in male Wistar rats from postnatal (PN) day 1 to 10 (early treatment) or from PN11 to 20 (late treatment) on: food intake, body mass, cardiovascular parameters, hormone profile, hypothalamic leptin signaling, glucose homeostasis and thyroid hormone-dependent proteins. The respective controls were injected with methanol-saline. ⋯ On the other hand, adult animals that were BRO-treated during the PN11-20 period showed hyperphagia, higher blood pressure, higher prolactinemia and OBR-b, higher TRH and plasma T3, hypercorticosteronemia as well as higher Dio2 and UCP1 mRNA expression in the brown adipose tissue. Glucose homeostasis was not changed treatment in either period. Our data show that early and late dopamine overexposure during lactation induces diverse metabolic disturbances later in life, increasing the risk of thyroid dysfunction and, consequently, changes in prolactinemia.
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Previous studies have demonstrated that orexinergic neurons involve in promoting emergence from anesthesia of propofol, an intravenous anesthetics, while whether both of orexin-A and orexin-B have promotive action on emergence via mediation of basal forebrain (BF) in isoflurane anesthesia has not been elucidated. In this study, we observed c-Fos expressions in orexinergic neurons following isoflurane inhalation (for 0, 30, 60, and 120min) and at the time when the righting reflex returned after the cessation of anesthesia. The plasma concentrations of orexin-A and -B in anesthesia-arousal process were measured by radioimmunoassay. ⋯ Administration of orexins had no effect on the induction time, but orexin-A facilitated the emergence of rats from isoflurane anesthesia while orexin-B didn't. Conversely, microinjection of the orexin receptor-1 antagonist SB-334867A delayed emergence from isoflurane anesthesia. The results indicate that orexin-A plays a promotive role in the emergence of isoflurane anesthesia and this effect is mediated by the basal forebrain.
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The orexins system consists of two G-protein coupled receptors (the orexin-1 and the orexin-2 receptor) and two neuropeptides, orexin-A and orexin-B. Orexin-A is an excitatory neuropeptide that regulates arousal, wakefulness and appetite. Recent studies have shown that orexin-A may promote gastric motility. ⋯ However, those effects could be partly blocked by pre-treatment with SB334867 in the LHA. It is suggested that orexin-A plays an important role in promoting gastric motility via LHA. The PVN may be involved in regulation of LHA on gastric motility.
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It has been implicated that electroacupuncture can relieve the symptoms of sciatica with the increase of pain threshold in human, and arginine vasopressin (AVP) in the brain rather than the spinal cord and blood circulation participates in antinociception. Our previous study has proven that AVP in the brain played a role in the process of electroacupuncture analgesia in rat. ⋯ The results showed that (1) AVP concentration of cerebrospinal fluid (CSF) (7.5 ± 2.5 pg/ml), not plasma (13.2 ± 4.2 pg/ml) in primary sciatica patients was lower than that in health volunteers (16.1 ± 3.8 pg/ml and 12.3 ± 3.4 pg/ml), although the osmotic pressure in CSF and plasma did not change; (2) electroacupuncture of the bilateral "Zusanli" points (St. 36) for 60 min relieved the pain sensation in primary sciatica patients; (3) electroacupuncture increased the AVP level of CSF, not plasma in primary sciatica patients; and (4) there was the positive correlation between the effect of electroacupuncture relieving the pain and the AVP level of CSF in the primary sciatica patients. The data suggested that central AVP, not peripheral AVP might improve the effect of electroacupuncture treatment of primary sciatica in human, i.e., central AVP might take part in the electroacupuncture relieving the pain sensation in primary sciatica patients.