Isolated Oculomotor Neuritis After Dengue Fever.

ABSTRACT: We report a rare case of isolated partial left III cranial nerve palsy due to inflammatory oculomotor neuritis after dengue fever with unique neuro-imaging findings of enhancement seen along the entire course of the oculomotor nerve.

Miller Fisher syndrome and polyneuritis cranialis in COVID-19.

OBJECTIVE: To report 2 patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who presented acutely with Miller Fisher syndrome and polyneuritis cranialis, respectively. METHODS: Patient data were obtained from medical records from the University Hospital "Príncipe de Asturias," Alcalá de Henares, and the University Hospital "12 de Octubre," Madrid, Spain. RESULTS: A 50-year-old man presented with anosmia, ageusia, right internuclear ophthalmoparesis, right fascicular oculomotor palsy, ataxia, areflexia, albuminocytologic dissociation, and positive testing for anti-GD1b-immunoglobulin G antibody. Five days previously, he had developed a cough, malaise, headache, low back pain, and fever. A 39-year-old man presented with ageusia, bilateral abducens palsy, areflexia, and albuminocytologic dissociation. Three days previously, he had developed diarrhea, a low-grade fever, and poor general condition. Oropharyngeal swab test for SARS-CoV-2 by qualitative real-time reverse transcriptase PCR assay was positive in both patients and negative in the CSF. The first patient was treated with IV immunoglobulin and the second with acetaminophen. Two weeks later, both patients made a complete neurologic recovery, except for residual anosmia and ageusia in the first case. CONCLUSIONS: Our 2 cases highlight the rare occurrence of Miller Fisher syndrome and polyneuritis cranialis during the coronavirus disease 2019 (COVID-19) pandemic. These neurologic manifestations may occur because of an aberrant immune response to COVID-19. The full clinical spectrum of neurologic symptoms in patients with COVID-19 remains to be characterized.

Sex-specific effects of prenatal valproic acid exposure on sociability and neuroinflammation: Relevance for susceptibility and resilience in autism.

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders with an incidence four times higher in boys than in girls. By analyzing the effect of sex in a mouse model of ASD, we were able to identify immune alterations that could underlie this sex bias. Pregnant mice were injected subcutaneously with 600 mg/kg of valproic acid (VPA) or saline at gestational day 12.5. Their male and female offspring were evaluated in a social interaction test at adulthood, and only male VPA mice showed reduced sociability levels and a lack of preference for the social stimulus over a novel object. We then analyzed the corticosterone (CORT) response to an inflammatory stimulus, as a measure of the hypothalamus-pituitary-adrenal (HPA) function, and the neuroinflammatory state in adult and young animals. Adult VPA males exhibited increased basal CORT levels, while VPA females showed levels comparable to controls. As male mice showed a blunted CORT response at PD21 when compared to female mice, we propose that this early dimorphism could explain the different effects of VPA on HPA function. In addition, prenatal VPA exposure resulted in altered astroglial and microglial cell density levels in the cerebellum and dentate gyrus of adult mice. These neuroinflammatory effects were more pronounced in females than males, and appeared at early developmental stages. Hence, these postnatal glial density differences could underlie the behavioral alterations observed in adulthood, when only males show a social deficit. Our work contributes to the understanding of biological mechanisms affected by VPA on male and female rodents and shed light on the study of possible resilience mechanisms in the female population and/or susceptibility to ASD in boys.

Neuropathic Pain and Itch Mechanisms Underlying Allergic Conjunctivitis.

OBJECTIVE: Among the constellation of symptoms that characterizes allergic conjunctivitis, many (eg, burning and stinging) can be attributed to chronic neuropathic pain. Cumulative data support that these hallmark symptoms might be linked to the effects of allergen-induced neuromodulation. This review investigates the key characteristics of neuropathic itch and pain in allergic conjunctivitis and their underlying pathogenic mechanisms. METHODS: A literature review was conducted using a PubMed search focusing on allergic conjunctivitis, neurogenic inflammation, neuropathic itch, and neuropathic pain. Articles were reviewed, and those discussing clinical course, pathophysiology, and neuronal regulation of chronic neuropathic symptoms as related to allergic disease were summarized. RESULTS: Recent evidence suggests that some symptoms of allergic conjunctivitis may be better represented as a chronic neuropathic disorder. We found that neurogenic mechanisms may have a significant role in chronic ocular surface inflammation from allergic inflammation. Manifestations may be associated with repeated ocular sensory nerve injury leading to an acute-to-chronic transition, which is in turn associated with neuropathologic changes (peripheral and central sensitization), neuronal dysfunction, and spontaneous ocular pain. CONCLUSION: Current goals in the management of allergic conjunctivitis aim to minimize the inflammatory cascade associated with the allergic response in the initial stages of the pathogenic mechanism. Based on the mechanistic data reviewed herein, the recognition that neuronal inflammation explains many of the symptoms in allergic conjunctivitis opens new frontiers for drug discovery.

Inflammatory and oxidative mechanisms potentiate bifenthrin-induced neurological alterations and anxiety-like behavior in adult rats.

Bifenthrin (BF) is a synthetic pyrethroid pesticide widely used in several countries to manage insect pests on diverse agricultural crops. Growing evidence indicates that BF exposure is associated with an increased risk of developing neurodegenerative disorders. However, the mechanisms by which BF induces neurological and anxiety alterations in the frontal cortex and striatum are not well known. The present in vivo study was carried out to determine whether reactive oxygen species (ROS)-mediated oxidative stress (OS) and neuroinflammation are involved in such alterations. Thirty-six Wistar rats were thus randomly divided into three groups and were orally administered with BF (0.6 and 2.1 mg/kg body weight, respectively) or the vehicle (corn oil), on a daily basis for 60 days. Results revealed that BF exposure in rats enhanced anxiety-like behavior after 60 days of treatment, as assessed with the elevated plus-maze test by decreases in the percentage of time spent in open arms and frequency of entries into these arms. BF-treated rats also exhibited increased oxidation of lipids and carbonylated proteins in the frontal cortex and striatum, and decreased glutathione levels and antioxidant enzyme activities including superoxide dismutase, catalase and glutathione peroxidase. Treatment with BF also increased protein synthesis and mRNA expression of the inflammatory mediators cyclooxygenase-2 (COX-2), microsomal prostaglandin synthase-1 (mPGES-1) and nuclear factor-kappaBp65 (NF-kBp65), as well as the production of tumor necrosis factor-α (TNF-α) and ROS. Moreover, BF exposure significantly decreased protein synthesis and mRNA expression of nuclear factor erythroid-2 (Nrf2) and acetylcholinesterase (AChE), as well as gene expression of muscarinic-cholinergic receptors (mAchR) and choline acetyltransferase (ChAT) in the frontal cortex and striatum. These data suggest that BF induced neurological alterations in the frontal cortex and striatum of rats, and that this may be associated with neuroinflammation and oxidative stress via the activation of Nrf2/NF-kBp65 pathways, which might promote anxiety-like behavior.

Time course of ongoing activity during neuritis and following axonal transport disruption.

Local nerve inflammation (neuritis) leads to ongoing activity and axonal mechanical sensitivity (AMS) along intact nociceptor axons and disrupts axonal transport. This phenomenon forms the most feasible cause of radiating pain, such as sciatica. We have previously shown that axonal transport disruption without inflammation or degeneration also leads to AMS but does not cause ongoing activity at the time point when AMS occurs, despite causing cutaneous hypersensitivity. However, there have been no systematic studies of ongoing activity during neuritis or noninflammatory axonal transport disruption. In this study, we present the time course of ongoing activity from primary sensory neurons following neuritis and vinblastine-induced axonal transport disruption. Whereas 24% of C/slow Aδ-fiber neurons had ongoing activity during neuritis, few (<10%) A- and C-fiber neurons showed ongoing activity 1-15 days following vinblastine treatment. In contrast, AMS increased transiently at the vinblastine treatment site, peaking on days 4-5 (28% of C/slow Aδ-fiber neurons) and resolved by day 15. Conduction velocities were slowed in all groups. In summary, the disruption of axonal transport without inflammation does not lead to ongoing activity in sensory neurons, including nociceptors, but does cause a rapid and transient development of AMS. Because it is proposed that AMS underlies mechanically induced radiating pain, and a transient disruption of axonal transport (as previously reported) leads to transient AMS, it follows that processes that disrupt axonal transport, such as neuritis, must persist to maintain AMS and the associated symptoms. NEW & NOTEWORTHY Many patients with radiating pain lack signs of nerve injury on clinical examination but may have neuritis, which disrupts axonal transport. We have shown that axonal transport disruption does not induce ongoing activity in primary sensory neurons but does cause transient axonal mechanical sensitivity. The present data complete a profile of key axonal sensitivities following axonal transport disruption. Collectively, this profile supports that an active peripheral process is necessary for maintained axonal sensitivities.

[Clinical observation on the evolution process of macular ganglion cell complex and peripapillary retinal nerve fiber layer of neuritis patients].

Objective: To discuss the dynamic changes and correlation of macular ganglion cell (mGCC) and peripapillary retinal nerve fiber layer (pRNFL) of neuritis patients through optical coherence tomography (OCT). Methods: A retrospective case series study. Eleven eyes from 11 patients who have been diagnosed with neuritis and received regular follow-up during June 2013 through June 2015 were included. The dynamic characteristic changes of mGCC and pRNFL over the course of disease, as well as their correlations between best visual acuity and visual field have been analyzed based on OCT measurements. Results: According to the observation on the 11 eyes of the 11 patients, patients showed symptoms of decreased vision, abnormal visual field, swollen mGCC and pRNFL with normal or increased thickness during the subnormal period. During the advance-separation period (around 3 weeks), the thickness of mGCC decreased resulting from atrophy while pRNFL was still swollen. Druing the late period (usually 6-8 weeks after onset of the disease), both mGCC and pRNFL were getting thinner due to atrophy. Vision acuity and visual field of the patients improved after treatment, however, they were still not comparable with the normal level before the disease. Conclusions: The thickness changes of mGCC and pRNFL differs in neuritis patients over time. OCT can help us in detecting these changes, thus provide a foundation for us to further explore the treatment and anatomical changes of neuritis patients. (Chin J Ophthalmol, 2018, 54: 62-68).

Aluminum exposure for 60days at an equivalent human dietary level promotes peripheral dysfunction in rats.

Aluminum (Al) is a neurotoxic associated with a number of chronic human diseases. We investigated the effects of Al exposure at doses similar to human dietary levels and at a high level exposure to Al on the peripheral nervous system. Wistar male rats were divided into two major groups and received orally: 1) First group - Low level - rats were subdivided and treated for 60days: a) Control - received ultrapure water; b) AlCl3 - received Al at 8.3mg/kg body weight (bw) for 60days; and 2) Second group - High level - rats were subdivided and treated for 42days: C) Control - received ultrapure water through oral gavage; d) AlCl3 - received Al at 100mg/kg bw for 42days. Von Frey hair test, plantar test, the presence of catalepsy and the spontaneous motor activity were investigated. Reactive oxygen species, lipid peroxidation and total antioxidant capacity, immunohistochemistry to investigate the nerve inflammation and, the specific presence of Al in the sciatic nerve fibers were investigated. Al exposure at a representative human dietary level promotes the development of mechanical allodynia, catalepsy, increased inflammation in the sciatic nerve, systemic oxidative stress and, is able to be retained in the sciatic nerve. The effects of low-dose Al were similar to those found in rats exposed to Al at a dose much higher (100mg/kg). Our findings suggest that Al may be considered toxic for the peripheral nervous system, thus inducing peripheral dysfunction.

Cannabinoid receptor agonist WIN55,212-2 and fatty acid amide hydrolase inhibitor URB597 ameliorate neuroinflammatory responses in chronic cerebral hypoperfusion model by blocking NF-κB pathways.

The present study explored the protective effects of cannabinoid receptor agonist WIN55,212-2 (WIN) and fatty acid amide hydrolase inhibitor URB597 (URB) against neuroinflammation in rats with chronic cerebral hypoperfusion (CCH). Activated microglia, astrocytes, and nuclear factor kappa B (NF-κB) p65-positive cells were measured by immunofluorescence. Reactive oxygen species (ROS) was assessed by dihydroethidium staining. The protein levels of cluster of differentiation molecule 11b (OX-42), glial fibrillary acidic protein (GFAP), NF-κB p65, inhibitor of kappa B alpha (IκB-a), IκB kinase a/ß (IKK a/ß), phosphorylated IKK a/ß (p-IKK a/ß), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and interleukin-1ß (IL-1ß) were examined by western blotting or enzyme-linked immunosorbent assay. All the protein levels of OX-42, GFAP, TNF-a, IL-1ß, COX-2, and iNOS are increased in CCH rats. WIN and URB downregulated the levels of OX-42, GFAP, TNF-α, IL-1ß, COX-2 and iNOS and inhibited CCH-induced ROS accumulation in CCH rats, indicating that WIN and URB might exert their neuroprotective effects by inhibiting the neuroinflammatory response. In addition, the NF-κB signaling pathway was activated by CCH in frontal cortex and hippocampus, while the aforementioned changes were reversed by WIN and URB treatment. These findings suggest that WIN and URB treatment ameliorated CCH-induced neuroinflammation through inhibition of the classical pathway of NF-κB activation, resulting in mitigation of chronic ischemic injury.

Group IV nociceptors develop axonal chemical sensitivity during neuritis and following treatment of the sciatic nerve with vinblastine.

We have previously shown that nerve inflammation (neuritis) and transient vinblastine application lead to axonal mechanical sensitivity in nociceptors innervating deep structures. We also have shown that these treatments reduce axonal transport and have proposed that this leads to functional accumulation of mechanically sensitive channels in the affected part of the axons. Though informing the etiology of mechanically induced pain, axonal mechanical sensitivity does not address the common report of ongoing radiating pain during neuritis, which could be secondary to the provocation of axonal chemical sensitivity. We proposed that neuritis and vinblastine application would induce sensitivities to noxious chemicals and that the number of chemo-sensitive channels would be increased at the affected site. In adult female rats, nerves were either untreated or treated with complete Freund's adjuvant (to induce neuritis) or vinblastine. After 3-7 days, dorsal root teased fiber recordings were taken from group IV neurons with axons within the sciatic nerve. Sciatic nerves were injected intraneurally with a combination of noxious inflammatory chemicals. Whereas no normal sciatic axons responded to this stimulus, 80% and 38% of axons responded in the neuritis and vinblastine groups, respectively. In separate experiments, sciatic nerves were partially ligated and treated with complete Freund's adjuvant or vinblastine (with controls), and after 3-5 days were immunolabeled for the histamine H3 receptor. The results support that both neuritis and vinblastine treatment reduce transport of the histamine H3 receptor. The finding that nociceptor axons can develop ectopic chemical sensitivity is consistent with ongoing radiating pain due to nerve inflammation.NEW & NOTEWORTHY Many patients suffer ongoing pain with no local pathology or apparent nerve injury. We show that nerve inflammation and transient application of vinblastine induce sensitivity of group IV nociceptor axons to a mixture of endogenous inflammatory chemicals. We also show that the same conditions reduce the axonal transport of the histamine H3 receptor. The results provide a mechanism for ongoing nociception from focal nerve inflammation or pressure without overt nerve damage.

Anti-natural octyl disaccharide-leprosy IDRI diagnostic (NDO-LID) antibodies as indicators of leprosy reactions and neuritis.

Background: Leprosy is a complex infectious and neurological disease caused by Mycobacterium leprae. Nerve damage is related to immunological hypersensitivity responses known as leprosy reactions (LRs). Diagnostic tools to predict LRs are not available. We hypothesized that natural octyl disaccharide-leprosy IDRI diagnostic (NDO-LID) would be helpful as an indicator of LRs and neuritis. Methods: To assess the utility of NDO-LID in indicating reactions, ELISA were used to detect specific antibodies in serum samples from 80 Colombian leprosy patients (40 with and 40 without history of LRs). Responses were detected using a range of detection reagents detecting IgG, IgM or both isotypes. Results: Patients with a history of LRs had an increased seropositivity rate for anti-NDO-LID antibodies compared to patients without (anti-NDO-LID protein A [p=0.02], IgG anti-NDO-LID [p=0.01] and IgM anti-NDO-LID [p=0.01]). Further analyses of patients with a history of LRs indicated that both seropositivity rate and magnitude of responses were elevated among patients with neuritis versus those without neuritis (anti-NDO-LID protein A [p=0.03], IgG anti-NDO-LID [p=0.001] and IgM anti-NDO-LID [p=0.06]). Conclusions: Our data indicate that testing for serum anti-NDO-LID antibodies can be a useful screen to identify patients at risk of developing LRs and neuritis.

Toward a more personalized motor function rehabilitation in Myotonic dystrophy type 1: The role of neuroplasticity.

Myotonic dystrophy type 1 (DM1) is the most prevalent adult muscular dystrophy, often accompanied by impairments in attention, memory, visuospatial and executive functions. Given that DM1 is a multi-system disorder, it requires a multi-disciplinary approach, including effective rehabilitation programs, focusing on the central nervous system neuroplasticity, in order to develop patient-tailored rehabilitative procedures for motor function recovery. Herein, we performed a transcranial magnetic stimulation (TMS) study aimed at investigating central motor conduction time, sensory-motor plasticity, and cortical excitability in 7 genetically defined DM1 patients. As compared to healthy individuals, DM1 patients showed a delayed central motor conduction time and an abnormal sensory-motor plasticity, with no alteration of cortical excitability. These findings may be useful to define patient-tailored motor rehabilitative programs.

Nontraumatic "isolated" posterior interosseous nerve palsy: Reinterpretation of electrodiagnostic studies and MRIs.

INTRODUCTION: Different hypotheses have been proposed for the pathophysiology of posterior interosseous nerve (PIN) palsy, namely compression, nerve inflammation, and fascicular constriction. We hypothesized that critical reinterpretation of electrodiagnostic (EDX) studies and MRIs of patients with a diagnosis of PIN palsy could provide insight into the pathophysiology and treatment. MATERIALS AND METHODS: We retrospectively reviewed patients with a diagnosis of nontraumatic PIN palsy and an upper extremity EDX and MRI. The original EDX studies and MRIs were reinterpreted by a neuromuscular neurologist and musculoskeletal radiologist, respectively, both blinded to our hypothesis. RESULTS: Fifteen patients met the inclusion criteria, i.e., having an "isolated" PIN palsy. Four patients (27%) had a defined mass compressing the PIN. The remaining 11 patients (73%) presented with at least one finding incompatible with the compression hypothesis: physical examination revealed that weakness in muscles was not innervated by the PIN in 4 patients (36%); EDX abnormalities not related to the PIN were found in 4 patients (36%); and reinterpretation of the MRIs showed muscle atrophy or nerve enlargement beyond the territory of the PIN in 9 patients (82%), without any evidence of compression of the PIN in the proximal forearm. CONCLUSION: The eleven patients in our series with presumed isolated and idiopathic PIN palsy had evidence of a more diffuse nerve-muscle involvement pattern, without any radiologic signs of nerve compression of the PIN itself. These data would favor an inflammatory pathophysiology when a structural lesion compressing the nerve is ruled out with imaging.

Minocycline in leprosy patients with recent onset clinical nerve function impairment.

Nerve function impairment (NFI) in leprosy may occur and progress despite multidrug therapy alone or in combination with corticosteroids. We observed improvement in neuritis when minocycline was administered in patients with type 2 lepra reaction. This prompted us to investigate the role of minocycline in recent onset NFI, especially in corticosteroid unresponsive leprosy patients. Leprosy patients with recent onset clinical NFI (<6 months), as determined by Monofilament Test (MFT) and Voluntary Muscle Test (VMT), were recruited. Minocycline 100mg/day was given for 3 months to these patients. The primary outcome was the proportion of patients with 'restored,' 'improved,' 'stabilized,' or 'deteriorated' NFI. Secondary outcomes included any improvement in nerve tenderness and pain. In this pilot study, 11 patients were recruited. The progression of NFI was halted in all; with 9 out of 11 patients (81.82%) showing ?restored? or ?improved? sensory or motor nerve functions, on assessment with MFT and VMT. No serious adverse effects due to minocycline were observed. Our pilot study demonstrates the efficacy and safety of minocycline in recent onset NFI in leprosy patients. However, larger and long term comparative trials are needed to validate the efficacy of minocycline in leprosy neuropathy.

Pain regulation by non-neuronal cells and inflammation.

Acute pain is protective and a cardinal feature of inflammation. Chronic pain after arthritis, nerve injury, cancer, and chemotherapy is associated with chronic neuroinflammation, a local inflammation in the peripheral or central nervous system. Accumulating evidence suggests that non-neuronal cells such as immune cells, glial cells, keratinocytes, cancer cells, and stem cells play active roles in the pathogenesis and resolution of pain. We review how non-neuronal cells interact with nociceptive neurons by secreting neuroactive signaling molecules that modulate pain. Recent studies also suggest that bacterial infections regulate pain through direct actions on sensory neurons, and specific receptors are present in nociceptors to detect danger signals from infections. We also discuss new therapeutic strategies to control neuroinflammation for the prevention and treatment of chronic pain.

P2X ion channel receptors and inflammation.

Neuroinflammation limits tissue damage in response to pathogens or injury and promotes repair. There are two stages of inflammation, initiation and resolution. P2X receptors are gaining attention in relation to immunology and inflammation. The P2X7 receptor in particular appears to be an essential immunomodulatory receptor, although P2X1 and P2X4 receptors also appear to be involved. ATP released from damaged or infected cells causes inflammation by release of inflammatory cytokines via P2X7 receptors and acts as a danger signal by occupying upregulated P2X receptors on immune cells to increase immune responses. The purinergic involvement in inflammation is being explored for the development of novel therapeutic strategies.

Anxiolytic effects of sesamin in mice with chronic inflammatory pain.

OBJECTIVE: Sesamin is known for its role in antioxidant, antiproliferative, antihypertensive, and neuroprotective activities. However, little is known about the role of sesamin in the development of emotional disorders. Here we investigated persistent inflammatory pain hypersensitivity and anxiety-like behaviors in the mouse suffering chronic pain. METHODS: Chronic inflammatory pain was induced by hind paw injection of complete Freund's adjuvant (CFA). Levels of protein were detected by Western blot. RESULTS: Administration of sesamin could induce anxiolytic activities but had no effect on analgesia. In the basolateral amygdala, a structure involving the anxiety development, sesamin attenuated the up-regulation of NR2B-containing N-methyl-d-aspartate receptors, GluR1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor as well as phosphorylation of GluR1 at Ser831 (p-GluR1-Ser831), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII-alpha) in the hind paw CFA-injected mice. In the same model, we found that the sesamin blocked the down-regulation of gamma-aminobutyric acid A (GABAA-alpha-2) receptors. CONCLUSION: Our findings show that sesamin reduces anxiety-like behaviors induced by chronic pain at least partially through regulating the GABAergic and glutamatergic transmission in the amygdala of mice.

Heat stress-induced memory impairment is associated with neuroinflammation in mice.

BACKGROUND: Heat stress induces many pathophysiological responses and has a profound impact on brain structure. It has been demonstrated that exposure to high temperature induces cognitive impairment in experimental animals and humans. Although the effects of heat stress have long been studied, the mechanisms by which heat stress affects brain structure and cognition not well understood. METHODS: In our longitudinal study of mice exposed to heat over 7, 14, or 42 days, we found that heat stress time dependently impaired cognitive function as determined by Y-maze, passive avoidance, and novel object recognition tests. To elucidate the histological mechanism by which thermal stress inhibited cognitive abilities, we examined heat stress-induced inflammation in the hippocampus. RESULTS: In mice subjected to heat exposure, we found: 1) an increased number of glial fibrillary acid protein (GFAP)- and macrophage-1 antigen (Mac-1)-positive cells, 2) up-regulated nuclear factor (NF)-κB, a master regulator of inflammation, and 3) marked increases in cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cytokine interleukin (IL)-1ß and tumor necrosis factor (TNF)-α in the mouse hippocampus. We also observed that neuronal and synaptic densities were degenerated significantly in hippocampal regions after heat exposure, as determined by histological analysis of neuronal nuclei (NeuN), postsynaptic density protein 95 (PSD-95), and synaptophysin expression. Moreover, in heat-exposed mice, we found that the number of cells positive for doublecortin (DCX), a marker of neurogenesis, was significantly decreased compared with control mice. Finally, anti-inflammatory agent minocycline inhibited the heat stress-induced cognitive deficits and astogliosis in mice. CONCLUSIONS: Together, these findings suggest that heat stress can lead to activation of glial cells and induction of inflammatory molecules in the hippocampus, which may act as causative factors for memory loss, neuronal death, and impaired adult neurogenesis.