Hyaluronic Acid Conjugated with 17ß-Estradiol Effectively Alleviates Estropause-Induced Cognitive Deficits in Rats.

Women are at a higher risk of cognitive impairments and Alzheimer's disease (AD), particularly after the menopause, when the estrous cycle becomes irregular and diminishes. Numerous studies have shown that estrogen deficiency, especially estradiol (E2) deficiency, plays a key role in this phenomenon. Recently, a novel polymeric drug, hyaluronic acid-17ß-estradiol conjugate (HA-E2), has been introduced for the delivery of E2 to brain tissues. Studies have indicated that HA-E2 crosses the blood-brain barrier (BBB) and facilitates a prolonged E2 release profile while lowering the risk of estrogen-supplement-related side effects. In this study, we used ovariohysterectomy (OHE) rats, a postmenopausal cognitive deficit model, to explore the effect of a 2-week HA-E2 treatment (210 ng/kg body weight, twice a week) on the cholinergic septo-hippocampal innervation system, synaptic transmission in hippocampal pyramidal neurons and cognitive improvements. Our study revealed an 11% rise in choline acetyltransferase (ChAT) expression in both the medial septal nucleus (MS nucleus) and the hippocampus, along with a 14-18% increase in dendritic spine density in hippocampal pyramidal neurons, following HA-E2 treatment in OHE rats. These enhancements prompted the recovery of cognitive functions such as spatial learning and memory. These findings suggest that HA-E2 may prevent and improve estrogen-deficiency-induced cognitive impairment and AD.

Gastroprotective effects of Machilus zuihoensis Hayata bark against acidic ethanol-induced gastric ulcer in mice.

Background and aim: In traditional medicine, Machilus zuihoensis Hayata bark (MZ) is used in combination with other medicines to treat gastric cancer, gastric ulcer (GU), and liver and cardiovascular diseases. This study aims to evaluate the gastroprotective effects and possible mechanism(s) of MZ powder against acidic ethanol (AE)-induced GU and its toxicity in mice. Experimental procedure: The gastroprotective effect of MZ powder was analyzed by orally administering MZ for 14 consecutive days before AE-inducing GU. Ulcer index (UI) and protection percentage were calculated, hematoxylin and eosin staining and periodic acid-Schiff staining were performed, and gastric mucus weights were measured. The antioxidative, anti-inflammatory, and anti-apoptotic mechanisms, and possible signaling pathway(s) were studied. Results and conclusion: Pretreatment with MZ (100 and 200 mg/kg) significantly decreased 10 µL/g AE-induced mucosal hemorrhage, edema, inflammation, and UI, resulted in protection percentages of 88.9% and 93.4%, respectively. MZ pretreatment reduced AE-induced oxidative stress by decreasing malondialdehyde level and restoring superoxide dismutase activity. MZ pretreatment demonstrated anti-inflammatory effects by reducing both serum and gastric tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß levels. Furthermore, MZ pretreatment exhibited anti-apoptotic effect by decreasing Bcl-2 associated X protein/B-cell lymphoma 2 ratio. The gastroprotective mechanisms of MZ involved inactivations of nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) and mitogen activated protein kinase (MAPK) signaling pathways. Otherwise, 200 mg/kg MZ didn't induce liver or kidney toxicity. In conclusion, MZ protects AE-induced GU through mucus secreting, antioxidative, anti-inflammatory, and anti-apoptotic mechanisms, and inhibitions of NF-κB and MAPK signaling pathways.

Active coping with stress suppresses glucose metabolism in the rat hypothalamus.

We used 18F-fluorodeoxyglucose small-animal positron-emission tomography to determine whether different styles of coping with stress are associated with different patterns of neuronal activity in the hypothalamus. Adult rats were subjected to immobilization (IMO)-stress or to a non-immobilized condition for 30 min, in random order on separate days, each of which was followed by brain-scanning. Some rats in the immobilized condition were allowed to actively cope with the stress by chewing a wooden stick during IMO, while the other immobilized rats were given nothing to chew on. Voxel-based statistical analysis of the brain imaging data shows that chewing counteracted the stress-induced increased glucose uptake in the hypothalamus to the level of the non-immobilized condition. Region-of-interest analysis of the glucose uptake values further showed that chewing significantly suppressed stress-induced increased glucose uptake in the paraventricular hypothalamic nucleus and the anterior hypothalamic area but not in the lateral hypothalamus. Together with the finding that the mean plasma corticosterone concentration at the termination of the IMO was also significantly suppressed when rats had an opportunity to chew a wooden stick, our results showed that active coping by chewing inhibited the activation of the hypothalamic-pituitary-adrenal axis to reduce the endocrine stress response.