[Interventional effect of metformin on pulmonary inflammation and pulmonary fibrosis in silicotic rats].

Objective: To investigate the interventional effect of metformin on pulmonary inflammation and pulmonary fibrosis in silicotic rats. Methods: In April 2019, 48 Wistar male rats of SPF grade were randomly divided into negative control group, metformin control group, silicon dioxide (SiO2) model group, low, medium and high dose metformin intervention group according to the random number table method, 8 rats in each group. The SiO2 model group and the low, medium and high dose metformin intervention groups were given 1 ml 50 mg/ml of SiO2 by intratracheal instillation, the negative control group and the metformin control group were given 1 ml normal saline by intratracheal instillation. 24 hours later, the low, medium and high dose metformin intervention groups and the metformin control group were treated with 100, 200, 400 and 400 mg/kg metformin daily, the control and SiO2 model groups received normal saline daily. Then the rats were sacrificed at the 28th day after SiO2 exposure. The changes of rat body weight and pathological examination of rat lung tissue were observed, and the lung organ coefficient, the content of hydroxyproline (HYP) , the expression levels of inflammatory factors transforming growth factor beta1 (TGF-ß1) , tumor necrosis factor-alpha (TNF-α) , interleukin-1beta (IL-1ß) and the protein expression of E-cadherin (E-Cad) , Vimentin, α-SMA were detected. Results: Compared with the negative control group, SiO2 model group had a significant decrease in the body weight of rats (P<0.05) , lung organ coefficient, alveolitis and fibrosis scores, HYP content and the levels of TGF-ß1, TNF-α, IL-1ß were all significantly increased (P<0.05) . Compared with the SiO2 model group, the weights of the rats in the medium and high dose intervention group of metformin increased significantly (P<0.05) . And after intervention with different doses of metformin, the lung organ coefficient, alveolitis and fibrosis scores, HYP content and the levels of TGF-ß1, TNF-α and IL-1ß were significantly decreased (P<0.05) . Immunohistochemistry and Western blotting results showed that compared with the negative control group, the expression of E-Cad of the SiO2 model group was decreased, and the expression levels of Vimentin and α-SMA were significantly increased (P<0.05) . After metformin intervention, the expression of E-Cad was significantly increased, the expression levels of Vimentin and α-SMA were significantly decreased (P<0.05) . Conclusion: Metformin can reduce lung tissue inflammation and fibrosis in rats exposed to SiO2 dust, which may be related to reducing the expression of inflammatory factors in lung tissue and inhibiting the EMT process.

Acoustic communication in two freshwater gobies: the relationship between ambient noise, hearing thresholds and sound spectrum.

Two freshwater gobies Padogobius martensii and Gobius nigricans live in shallow (5-70 cm) stony streams, and males of both species produce courtship sounds. A previous study demonstrated high noise levels near waterfalls, a quiet window in the noise around 100 Hz at noisy locations, and extremely short-range propagation of noise and goby signals. To investigate the relationship of this acoustic environment to communication, we determined audiograms for both species and measured parameters of courtship sounds produced in the streams. We also deflated the swimbladder in P. martensii to determine its effect on frequency utilization in sound production and hearing. Both species are maximally sensitive at 100 Hz and produce low-frequency sounds with main energy from 70 to 100-150 Hz. Swimbladder deflation does not affect auditory threshold or dominant frequency of courtship sounds and has no or minor effects on sound amplitude. Therefore, both species utilize frequencies for hearing and sound production that fall within the low-frequency quiet region, and the equivalent relationship between auditory sensitivity and maximum ambient noise levels in both species further suggests that ambient noise shapes hearing sensitivity.

The otic gasbladder as an ancillary auditory structure in a mormyrid fish.

Mormyrid fishes use acoustic signals for long-distance communication and a weakly electric field for short-distance interaction. Mormyrids are unique in having an otic gasbladder attached directly to the saccule on each side of the inner ear. Karl von Frisch (1938) hypothesized that the tightly coupled otic gasbladder might aid mormyrid hearing. Using the mormyrid fish (Brienomyrus brachyistius), this study manipulated gas in the otic gasbladder to test this hypothesis and histological sections were made to examine the anatomical relationship between the gasbladder and inner ear. The hearing sensitivity curves (audiograms) were obtained with the auditory brainstem response protocol. Audiograms were obtained from normal fish and from fish in which gas was withdrawn from either one or two otic gasbladders. Removal of gas from one otic gasbladder did not result in a significant change in either hearing ability or acoustically evoked brainwaves as compared to the control fish. Bilateral deflation of the otic gasbladders led to significant threshold changes. Histological sections revealed a particularly close coupling between the otic gasbladder and the saccule chamber. These results support von Frisch's hypothesis that the otic gasbladders of mormyrids assist in underwater sound detection.

Effects of antiglaucoma drugs on the blood flow in rabbit eyes.

Although it is essential that intraocular pressure (IOP) be reduced in glaucoma treatment, it is also vitally important to provide sufficient blood flow to eye tissues so that healthy visual field is maintained. It is possible for an agent to reduce IOP and blood supply to the eye. In that case, glaucoma appears to be under control since IOP has been reduced to within normal range, yet the disease is actually progressing, causing damage to the retina, optic nerve, and other tissues. The 85Sr-microsphere technique was used to study the effects of several antiglaucoma drugs on blood supply to various eye tissues. It was found that pilocarpine, L-timolol, D-timolol and haloperidol are good drugs to use in treating glaucoma because they do not reduce ocular blood flow. D-timolol is particularly good because it does not cause side effects through beta-adrenergic blockade or cholinergic stimulation. On the other hand, trifluperidol and moperone reduce IOP effectively, but also decrease blood supply.