Susceptibility of subregions of prefrontal cortex and corpus callosum to damage by high-dose oxytocin-induced labor in male neonatal mice.

Induction and augmentation of labor is one of the most common obstetrical interventions. However, this intervention is not free of risks and could cause adverse events, such as hyperactive uterine contraction, uterine rupture, and amniotic-fluid embolism. Our previous study using a new animal model showed that labor induced with high-dose oxytocin (OXT) in pregnant mice resulted in massive cell death in selective brain regions, specifically in male offspring. The affected brain regions included the prefrontal cortex (PFC), but a detailed study in the PFC subregions has not been performed. In this study, we induced labor in mice using high-dose OXT and investigated neonatal brain damage in detail in the PFC using light and electron microscopy. We found that TUNEL-positive or pyknotic nuclei and Iba-1-positive microglial cells were detected more abundantly in infralimbic (IL) and prelimbic (PL) cortex of the ventromedial PFC (vmPFC) in male pups delivered by OXT-induced labor than in the control male pups. These Iba-1-positive microglial cells were engulfing dying cells. Additionally, we also noticed that in the forceps minor (FMI) of the corpus callosum (CC), the number of TUNEL-positive or pyknotic nuclei and Iba-1-positive microglial cells were largely increased and Iba-1-positive microglial cells phagocytosed massive dying cells in male pups delivered by high-dose OXT-induced labor. In conclusion, IL and PL of the vmPFC and FMI of the CC, were susceptible to brain damage in male neonates after high-dose OXT-induced labor.

An integrated study of metabolomics and transcriptomics to reveal the anti-primary dysmenorrhea mechanism of Akebiae Fructus.

ETHNOPHARMACOLOGICAL RELEVANCE: Akebiae Fructus, a Tujia minority folk medicine and a well-known traditional Chinese medicine for soothing the liver, regulating Qi, promoting blood circulation and relieving pain, is widely used in the treatment of primary dysmenorrhea. However, little is known about its underlying mechanism. AIM OF THE STUDY: To explore the effect of Akebiae Fructus on primary dysmenorrhea model induced by estradiol benzoate and oxytocin, and to provide better understanding of the mechanism of Akebiae Fructus for primary dysmenorrhea treatment. MATERIALS AND METHODS: The primary dysmenorrhea mouse model was used in this study. Except for the control group and the normal administration group, the mice of other groups were subcutaneously injected with estradiol benzoate (10 mg/kg/d) for 10 consecutive days. From the 5th day of the ten-day model period, the positive control groups were given 0.075 g/kg ibuprofen and 7.5 g/kg Leonurus granule, the drug groups were given 0.2 g/kg, 0.4 g/kg, 0.8 g/kg Akebiae Fructus extract, the normal administration group was given 0.8 g/kg Akebiae Fructus extract, and the same volume saline was given in the control group. On the tenth day, oxytocin (10 U/kg) was peritoneally injected after estradiol benzoate injected 1 h. After the oxytocin injection, writhing behavior was observed for 30 min. Then the uterine tissue was collected to measure the level of PGF2α and PGE2, and for histological analysis and transcriptomics analysis. Meanwhile, plasma and urine samples were collected for metabolomic analysis. RESULTS: Akebiae Fructus inhibited the writhing, decreased the PGF2α level and ameliorated the morphological changes. 32 potential metabolic biomarkers in plasma and 17 in urine were found for primary dysmenorrhea, and after Akebiae Fructus treatment, 25 metabolites in plasma and 14 in urine were restored. These altered metabolites were mainly involved in lipid, amino acid and organic acid metabolism. For the transcriptomic study, a total of 2244 differentially expressed genes (1346 up-regulated and 898 down-regulated) were obtained between the control and model group, and 148 differentially expressed genes (DEGs) were found related with Akebiae Fructus treatment of primary dysmenorrhea. Correlation analysis was carried out based on the transcriptomic and metabolomic data. 5 differentially expressed genes (Plpp3, Sgpp2, Arg1, Adcy8, Ak5) were found related with the enrichment metabolic pathways. The mechanism by which Akebiae Fructus ameliorates primary dysmenorrhea may account for the regulation of the gene expression to control the key enzymes in the sphingolipid metabolism, arginine and proline metabolism, glycerophospholipid metabolism and purine metabolism, inhibiting the abnormal secretion of PGF2α, alleviating the uterine contraction and reducing inflammation and pain. CONCLUSIONS: Akebiae Fructus could effectively alleviate the symptoms of primary dysmenorrhea, regulate metabolic disorders, and control the related gene expression in primary dysmenorrhea. The study may provide clues for further study of Akebiae Fructus treatment on primary dysmenorrhea.

Preclinical toxicity screening of intrathecal oxytocin in rats and dogs.

BACKGROUND: Anatomic, physiologic, and behavioral studies in animals suggest that spinally released oxytocin should produce analgesia in humans and may also protect from chronic pain after injury. In this article, the authors report preclinical toxicity screening of oxytocin for intrathecal delivery. METHODS: Intrathecal oxytocin, 11 µg (6 U) or vehicle, was injected intrathecally in 24 rats, followed by frequent behavioral assessment and histologic examination of spinal contents 2 or 14 days after injection. In three dogs, a range of intrathecal oxytocin doses (18 to 550 µg in 0.5 ml) was injected followed by physiologic, biochemical, and behavioral assessments. Ten dogs were then randomized to receive five daily injections of intrathecal oxytocin, 550 µg in 0.5 ml, or vehicle with similar assessments and, necropsy and histologic analysis were conducted 2 days later. RESULTS: In rats, intrathecal oxytocin resulted in transient scratching and itching behaviors, without other differences from vehicle. There was no behavioral, gross anatomic, or histologic evidence of neurotoxicity. Dose ranging in dogs suggested mild effects on motor tone, blood pressure, and heart rate at the 550 µg dose. Repeated boluses in dogs did not produce behavioral, biochemical, neurological, gross anatomic, or histologic evidence of neurotoxicity. CONCLUSIONS: Substances, including natural neurotransmitters, may be toxic when administered in pharmacologic doses in the spinal cord. This preclinical toxicity screen in two species suggests that bolus injections of oxytocin in concentrations up to 1,100 µg/ml are unlikely to cause neurotoxicity. The authors also support cautious clinical application of intrathecal oxytocin under regulatory supervision.

The nature of the sheep chorionic oxytocic substance.

The effects of infusions of fresh sheep placenta in normal saline and the filtrate obtained therefrom after boiling for 15 min were investigated on guinea-pig and rat uteri, other mammalian non-vascular smooth muscles and the cardiovascular system, noting their responses to the infusion/filtrate in the presence or absence of various inhibitors or agonists. Solvent partition, acute toxicity and thin layer chromatography (TLC) studies were also performed. It was found that the infusion/filtrate had oxytocic activity independent of histamine and muscarinic receptors. It had H(1) receptor activity agonist action on the guinea-pig ileum, antagonized adrenaline-induced contractions in the vas but unlike bradykinin did not relax rat duodenum. It induced vasoconstriction in the rat hindquarters, depressed cat blood pressure but had positive inotropic effect on the guinea-pig Langendorff heart. Only the eluent from the least mobile of the five TLC bands on silica gel had oxytocic activity. It was concluded that the sheep chorionic oxytocic substance is not acetylcholine, histamine, 5-hydroxytryptamine, noradrenaline, adrenaline, prostaglandins F or E but is a peptide, which is not bradykinin, vasopressin or oxytocin.