Thermoregulatory pathway underlying the pyrogenic effects of prostaglandin E2 in the lateral parabrachial nucleus of male rats.

It has been shown that prostaglandin (PG) E2 synthesized in the lateral parabrachial nucleus (LPBN) is involved in lipopolysaccharide-induced fever. But the neural mechanisms of how intra-LPBN PGE2 induces fever remain unclear. In this study, we investigated whether the LPBN-preoptic area (POA) pathway, the thermoafferent pathway for feed-forward thermoregulatory responses, mediates fever induced by intra-LPBN PGE2 in male rats. The core temperature (Tcore) was monitored using a temperature radiotelemetry transponder implanted in rat abdomen. We showed that microinjection of PGE2 (0.28 nmol) into the LPBN significantly enhanced the density of c-Fos-positive neurons in the median preoptic area (MnPO). The chemical lesioning of MnPO with ibotenate or selective genetic lesioning or inhibition of the LPBN-MnPO pathway significantly attenuated fever induced by intra-LPBN injection of PGE2. We demonstrated that EP3 receptor was a pivotal receptor for PGE2-induced fever, since microinjection of EP3 receptor agonist sulprostone (0.2 nmol) or EP3 receptor antagonist L-798106 (2 nmol) into the LPBN mimicked or weakened the pyrogenic action of LPBN PGE2, respectively, but this was not the case for EP4 and EP1 receptors. Whole-cell recording from acute LPBN slices revealed that the majority of MnPO-projecting neurons originating from the external lateral (el) and dorsal (d) LPBN were excited and inhibited, respectively, by PGE2 perfusion, initiating heat-gain and heat-loss mechanisms. The amplitude but not the frequency of spontaneous and miniature glutamatergic excitatory postsynaptic currents (sEPSCs and mEPSCs) in MnPO-projecting LPBel neurons increased after perfusion with PGE2; whereas the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) and the A-type potassium (IA) current density did not change. In MnPO-projecting LPBd neurons, neither sEPSCs nor sIPSCs responded to PGE2; however, the IA current density was significantly increased by PGE2 perfusion. These electrophysiological responses and the thermoeffector reactions to intra-LPBN PGE2 injection, including increased brown adipose tissue thermogenesis, shivering, and decreased heat dissipation, were all abolished by L-798106, and mimicked by sulprostone. These results suggest that the pyrogenic effects of intra-LPBN PGE2 are mediated by both the inhibition of the LPBd-POA pathway through the EP3 receptor-mediated activation of IA currents and the activation of the LPBel-POA pathway through the selective enhancement of glutamatergic synaptic transmission via EP3 receptors.

[A case of duodenal ulcer as prominent manifestation of IgG4-related disease].

A case of IgG4-related disease presented with a duodenal ulcer to improve the understan-ding of IgG4-related diseases was reported. A 70-year-old male presented with cutaneous pruritus and abdominal pain for four years and blackened stools for two months. Four years ago, the patient went to hospital for cutaneous pruritus and abdominal pain. Serum IgG4 was 3.09 g/L (reference value 0-1.35 g/L), alanine aminotransferase 554 U/L (reference value 9-40 U/L), aspartate aminotransferase 288 U/L (reference value 5-40 U/L), total bilirubin 54.16 µmol/L (reference value 2-21 µmol/L), and direct bilirubin 29.64 µmol/L (reference value 1.7-8.1 µmol/L) were all elevated. The abdominal CT scan and magnetic resonance cholangiopancreatography indicated pancreatic swelling, common bile duct stenosis, and secondary obstructive dilation of the biliary system. The patient was diagnosed with IgG4-related disease and treated with prednisone at 40 mg daily. As jaundice and abdominal pain improved, prednisone was gradually reduced to medication discontinuation. Two months ago, the patient developed melena, whose blood routine test showed severe anemia, and gastrointestinal bleeding was diagnosed. The patient came to the emergency department of Beijing Hospital with no improvement after treatment in other hospitals. Gastroscopy revealed a 1.5 cm firm duodenal bulb ulcer. After treatment with omeprazole, the fecal occult blood was still positive. The PET-CT examination was performed, and it revealed no abnormality in the metabolic activity of the duodenal wall, and no neoplastic lesions were found. IgG4-related disease was considered, and the patient was admitted to the Department of Rheumatology and Immunology of Beijing Hospital for further diagnosis and treatment. The patient had a right submandibular gland mass resection history and diabetes mellitus. After the patient was admitted to the hospital, the blood test was reevaluated. The serum IgG4 was elevated at 5.44 g/L (reference value 0.03-2.01 g/L). Enhanced CT of the abdomen showed that the pancreas was mild swelling and was abnormally strengthened, with intrahepatic and extrahepatic bile duct dilation and soft tissue around the superior mesenteric vessels. We pathologically reevaluated and stained biopsy specimens of duodenal bulbs for IgG and IgG4. Immunohistochemical staining revealed remarkable infiltration of IgG4-positive plasma cells into duodenal tissue, the number of IgG4-positive cells was 20-30 cells per high-powered field, and the ratio of IgG4/IgG-positive plasma cells was more than 40%. The patient was treated with intravenous methylprednisolone at 40 mg daily dosage and cyclophosphamide, and then the duodenal ulcer was healed. IgG4 related disease is an immune-medicated rare disease characterized by chronic inflammation and fibrosis. It is a systemic disease that affects nearly every anatomic site of the body, usually involving multiple organs and diverse clinical manifestations. The digestive system manifestations of IgG4-related disease are mostly acute pancreatitis and cholangitis and rarely manifest as gastrointestinal ulcers. This case confirms that IgG4-related disease can present as a duodenal ulcer and is one of the rare causes of duodenal ulcers.