Persistent neuroinflammation and behavioural deficits after single mild traumatic brain injury

Despite an apparently silent imaging, some patients with mild traumatic brain injury (TBI) experience cognitive dysfunctions, which may persist chronically. Brain changes responsible for these dysfunctions are unclear and commonly overlooked. It is thus crucial to increase our understanding of the mechanisms linking the initial event to the functional deficits, and to provide objective evidence of brain tissue alterations underpinning these deficits. We first set up a murine model of closed-head controlled cortical impact, which provoked persistent cognitive and sensorimotor deficits, despite no evidence of brain contusion or bleeding on MRI, thus recapitulating features of mild TBI. Molecular MRI for P-selectin, a key adhesion molecule, detected no sign of cerebrovascular inflammation after mild TBI, as confirmed by immunostainings. By contrast, in vivo PET imaging with the TSPO ligand [18F]DPA-714 demonstrated persisting signs of neuroinflammation in the ipsilateral cortex and hippocampus after mild TBI. Interestingly, immunohistochemical analyses confirmed these spatio-temporal profiles, showing a robust parenchymal astrogliosis and microgliosis, at least up to 3 weeks post-injury in both the cortex and hippocampus. In conclusion, we show that even one single mild TBI induces long-term behavioural deficits, associated with a persistent neuro-inflammatory status that can be detected by PET imaging.

Role of inflammation in alcohol-related brain abnormalities: a translational study

Brain abnormalities observed in alcohol use disorder are highly heterogeneous in nature and severity, possibly because chronic alcohol consumption also affects peripheral organs leading to comorbidities that can result in exacerbated brain alterations. Despite numerous studies focussing on the effects of alcohol on the brain or liver, few studies have simultaneously examined liver function and brain damage in alcohol use disorder, and even fewer investigated the relationship between them except in hepatic encephalopathy. And yet, liver dysfunction may be a risk factor for the development of alcohol-related neuropsychological deficits and brain damage well before the development of liver cirrhosis, and potentially through inflammatory responses. The use of animal models enables a better understanding of the pathophysiological mechanisms underlying liver–brain relationships in alcohol use disorder, and more particularly of the inflammatory response at the tissue, cerebral and hepatic levels. The objective of this translational study was to investigate, both in alcohol use disorder patients and in a validated animal model of alcohol use disorder, the links between peripheral inflammation, liver damage and brain alterations. To do this, we conducted an in vivo neuroimaging examination and biological measures to evaluate brain volumes, liver fibrosis and peripheral cytokines in alcohol use disorder patients. In selectively bred Sardinian alcohol-preferring rats, we carried out ex vivo neuroimaging examination and immunohistochemistry to evaluate brain and liver inflammatory responses after chronic (50 consecutive weeks) alcohol drinking. In recently abstinent and non-cirrhotic alcohol use disorder patients, the score of liver fibrosis positively correlated with subcortical regions volumes (especially in right and left putamen) and level of circulating proinflammatory cytokines. In Sardinian alcohol-preferring rats, we found macrostructural brain damage and microstructural white matter abnormalities similar to those found in alcohol use disorder patients. In addition, in agreement with the results of peripheral inflammation observed in the patients, we revealed, in Sardinian alcohol-preferring rats, inflammatory responses in the brain and liver were caused by chronic alcohol consumption. Since the liver is the main source of cytokines in the human body, these results suggest a relationship between liver dysfunction and brain damage in alcohol use disorder patients, even in the absence of major liver disease. These findings encourage considering new therapeutic strategies aiming at treating peripheral organs to limit alcohol-related brain damage.

Alcohol exposure-induced neurovascular inflammatory priming impacts ischemic stroke and is linked with brain perivascular macrophages

Alcohol abuse is a major public health problem worldwide, causing a wide range of preventable morbidity and mortality. In this translational study, we show that heavy drinking (HD) (≥6 standard drinks/day) is independently associated with a worse outcome for ischemic stroke patients. To study the underlying mechanisms of this deleterious effect of HD, we performed an extensive analysis of the brain inflammatory responses of mice chronically exposed or not to 10% alcohol before and after ischemic stroke. Inflammatory responses were analyzed at the parenchymal, perivascular, and vascular levels by using transcriptomic, immunohistochemical, in vivo 2-photon microscopy and molecular MRI analyses. Alcohol-exposed mice show, in the absence of any other insult, a neurovascular inflammatory priming (i.e., an abnormal inflammatory status including an increase in brain perivascular macrophages [PVM]) associated with exacerbated inflammatory responses after a secondary insult (ischemic stroke or LPS challenge). Similar to our clinical data, alcohol-exposed mice showed larger ischemic lesions. We show here that PVM are key players on this aggravating effect of alcohol, since their specific depletion blocks the alcohol-induced aggravation of ischemic lesions. This study opens potentially new therapeutic avenues aiming at blocking alcohol-induced exacerbation of the neurovascular inflammatory responses triggered after ischemic stroke.

[Effects of progesterone and nomegestrol acetate on the endometrial epithelium of the rabbit. A study with scanning electron microscopy]

Immature female rabbits were tested by the Clauberg-MacPhail technique using progesterone (P), or nomegestrol acetate (NOM), a 19-norprogesterone derivative. The endometrial surface was observed by scanning electron microscopy. Estrogen priming followed by treatment with P induced changes on the endometrial surface which were very close to those observed in menopausal women under sequential estroprogestative therapy. After treatment with NOM the aspect of endometrium surface was very close to those observed after treatment with P. This is in accordance with the pharmacological profile of the product. Scanning electron microscopy confirms the previsional value of Clauberg-MacPhail's test and provides useful complementary information for the pharmacological understanding of a new synthetic progestogen.

Pharmacological profile of the new pituitary-gonadic suppressant 17 beta-acetoxy-5 alpha, 17 alpha-pregn-2-ene-20-yne

17 beta-Acetoxy-5 alpha, 17 alpha-pregn-2-ene-20-yne (TX 380) strongly suppresses the hypophyso-gonadic axis at central and peripheral levels. Depending on the dosage and on the hormonal status at the time of treatment, this combined inhibition results in major disturbances of the estrus cycle and in impaired ovulation. TX 380 shows minimal androgenic activity. It exerts no effect on the fetal female urogenital tract during gestation. TX 380 possesses only weak estrogenic properties, and does not promote endometrial proliferation in the female rabbit. Moreover, it markedly opposes the action of progesterone. Given this pharmacological profile, TX 380 stands as a candidate drug in the treatment of gynecologic affections, such as endometriosis and benign breast disease, and as a potential contraceptive agent.

[The endometrium of intact or castrated rats. Effects of hormonal stimulation. A scanning electron microscopy study]

The endometrium of female rats during the estrous cycle and of female ovariectomised rats under hormone stimulation, has been studied by scanning electron microscopy. The endometrium underwent marked cyclical changes; the development of microvilli was noted before ovulation, and secretory phenomena started during proestrus but remained discrete throughout the cycle. The rat endometrium was also characterised by the fact that ciliated cells were scarce. Following ovariectomy, the endometrial surface pattern was similar to that of the menopausal woman endometrium. After estrogen or estroprogestogen stimulation, by the methods usually employed in endocrine pharmacology, the general endometrial pattern was very different to that observed during the reproductive cycle in rats.