BACKGROUND: Central oxytocin (OT) may be a neurotransmitter or neuromodulator and play an important role in learning and memory, sexual behaviour, pain modulation and opiate tolerance and dependence. To research the interactions between oxytocinergic and opioidergic system in hippocampus has some significance.OBJECTIVE: To investigate the effects of OT administered intracerebroventricularly on evoked discharge of left dorsal hippocampal CA1 neurons in rats and the possible interactions between oxytocinergic and opioidergic system.DESIGN: A randomised controlled study.SETTING: Department of Physiology of Guangdong Medical College; Department of Physiology and Pathology of Medical College of Wuhan University.MATERIALS: The study was conducted in the Physiology Department of Medical College of Wuhan University from September 2002 to September 2003. A total of 36 male Sprague-Dawley rats were selected and randomly divided into six groups: control (NS), OT groups (0.2 mg/L, 2 mg/L and 20 mg/L), [d (CH2)5-OVT]+OT (2 mg/L), naloxone+OT (2 mg/L), with 6 rats in each group.METHODS: Single-unit recording was performed with glass microelectrode. The glass microelectrode was inserted by a micromanipulator into hippocampal CA1. The electrical activity was amplified by a microelectrode amplifier and then recorded by the biological experimental system,monitored at the same time with oscilloscope. When recording the neural discharge, electrical stimulation of the sciatic nerves was performed once 5minutes through a double stainless electrode. 5 μL oxytocin in dosage of 0.2, 2 and 20 mg/L were injected slowly into lateral ventricle via microlitre syringe. [d(CH2)5-OVT]+OT (2 mg/L) group: 2.5 μL [d(CH2)5-OVT](80 mg/L) was injected into lateral ventricle and then 2.5 μL oxytocin (2 mg/L). Naloxone+OT (2 mg/L) group: 2.5 μL naloxone (400 mg/L) was injected into lateral ventricle and then 2.5 μL oxytocin (2 mg/L). According to frequency of discharge, effect of oxytocin at various dosages on discharge induced by neurons in hippocampal CA1 area and [d (CH2)5-OVT]and naloxone on oxytocin was assayed. MAIN OUTCOME MEASURE: Changes of discharge frequency after stimulation.RESULTS: Data of totally 36 rats were entered the final analysis. ① OT (0.2 mg/L, 2 mg/L and 20 mg/L) administered by intracerebroventricularly could decrease the evoked discharge of hippocampal CA1 neurons in a dose-dependent manner. ② The inhibitory effects of OT (2 mg/L) could be blocked by pretreated intracerebroventricularly injection of [d (CH2)5-OVT](80 mg/L, 2.5 μL). ③ Intracerebroventricular injection of naloxone (400 mg/L, 2.5 μL) could attenuate the effects of OT (2 mg/L) significantly.CONCLUSION: OT can inhibit the electrical activities of hippocampal CA1 neurons to external electrical signal through activating the oxytocin receptor. Moreover, central opioid receptor is involving in the inhibitory effects of OT.

Objective:To summarize the clinical characteristics of patients with coronavirus disease 2019 (COVID-19) infected with Delta variant, so as to provide further references for clinical diagnosis and treatment.Methods:A real-world study was conducted to analyze the characteristics of 166 COVID-19 patients infected with Delta variant at Guangzhou Eighth People’s Hospital, Guangzhou Medical University.Results:The study enrolled 5 asymptomatic cases, 123 non-severe cases (mild and moderate type), and 38 severe cases (severe and critical type). Among these patients, 69 (41.6%) were male and 97 (58.4%) were female, with a mean age of 47.0±23.5 years. Thirty-nine cases (23.5%) had received 1 or 2 doses of inactivated vaccine. The incidence of severe COVID-19 cases was 7.7% in 2-doses vaccinated patients, which was lower than that of 11.5% in 1-dose and 26.8% in unvaccinated patients. The proportion of severe cases in 2 dose-vaccinated patients was 7.7%, which was lower than that of 11.5% in 1-dose vaccinated patients and 26.8% in unvaccinated patients, but the difference was not significant ( P>0.05). The most common clinical symptom was fever (134 cases, 83.2%), and 39.1% of cases presented with high-grade fever (≥39 °C); other symptoms were cough, sputum, fatigue, and xerostomia. The proportion of fever in severe cases was significantly higher than that of non-severe cases (97.4% vs. 76.4%, P<0.01). Similarly, the proportion of severe cases with high peak temperature (≥39 ℃) () was also higher than that of non-severe cases (65.8% vs. 30.9%, P<0.01). The median minimal Cycle threshold (Ct) values of viral nucleic acid N gene and ORFlab gene were 20.3 and 21.5, respectively, and the minimum Ct values were 11.9 and 13.5, respectively. Within 48 h of admission, 9.0% of cases presented with decreased white blood cell counts, and 52.4% with decreased lymphocyte counts. The proportions of increased C-reactive protein, serum amyloid A, interleukin 6, and interleukin 10 were 32.5%, 57.4%, 65.3%, and 35.7%, respectively. The proportions of elevated C-reactive protein, serum amyloid A and interleukin-6 in severe cases were significantly higher than those in non-severe cases ( P<0.01). Logistic regression analysis showed that older age and higher peak temperature were associated with a higher likelihood of severe cases ( OR>3, 95% CI: 2-7, P<0.01). In terms of treatment, traditional Chinese medicine (TCM) was used in 97.6% of non-severe cases and 100% in severe cases. Other treatments included respiratory and nutritional support, immunotherapy (such as neutralizing antibodies and plasma of recovered patients). The median times from admission to progression to severe cases, of fever clearance, and of nucleic acid conversion were 5 days, 6 days and 19 days, respectively. No deaths were reported within 28 days. Conclusions:The symptoms of Delta variant infection in Guangzhou are characterized by a high proportion of fever, high peak temperature, long duration of fever, high viral load, a long time to nucleic acid conversion, and a high incidence of severe cases. The severe cases exhibit a higher percentage of elderly patients, a longer duration of fever and have a higher fever rate and a higher hyperthermia rate than non-severe cases. Age and hyperthermia are independent risk factors for progression to severe disease. The combination of TCM and Western medicine can control the progression of the disease effectively.