Blocking autophagy by the two-pore channels antagonist tetrandrine improves sorafenib-induced death of hepatocellular carcinoma cells

Sorafenib, an oral multi-kinase inhibitor, used to treat hepatocellular carcinoma (HCC). However, drug resistance is still common in several HCC patients. This complex mechanism is not yet fully elucidated, driving the search for new therapeutic targets to potentiate the antitumoral effect of sorafenib. Recent findings have linked the expression of Two-Pore Channels (TPCs) receptors with the development and progression of cancer. TPCs receptors are stimulated by NAADP, a Ca²⁺ messenger, and inhibited by their antagonists Ned-19 and tetrandrine. Here, we investigate the participation of TPCs inhibition in cell death and autophagy in sorafenib-treated HCC cells. Here, we show that the association of sorafenib with tetrandrine increased sorafenib-induced cell death accompanied by increased lysotracker fluorescence intensity. In contrast, these effects were not observed after treating these cells with Ned-19. The pharmacological TPC antagonists by Ned-19 and tetrandrine or siRNA-mediated TPC1/2 inhibition decreased sorafenib-induced Ca²⁺ release, reinforcing the participation of TPCs in sorafenib HCC responses. Furthermore, the association tetrandrine and sorafenib blocked autophagy through ERK1/2 pathway inhibition, which represents a putative target for potentiating HCC cell death. Therefore, our study proposes the use of tetrandrine analogs with the aim of improving sorafenib therapy. Also, our data also allow us to suggest that TPCs may be a new target in anticancer therapies.

Memory and anxiety-like behavior of rats in the plus-maze discriminative avoidance task: Role of serotonergic transmission in the basolateral amygdala

Optimal levels of anxiety are critical to memory consolidation, but maladaptive anxiety can disrupt memory acquisition. Serotonergic activity within the amygdala influences both anxiety-like behavior and aversive memory consolidation. To evaluate the effects of serotoninergic manipulations within the basolateral amygdala (BLA) on anxiety-like behavior and aversive memory in rats tested in the plus-maze discriminative avoidance task (PMDAT). The PMDAT investigates aversive memory and anxiety-like behavior simultaneously in rodents. Three-month-old male Wistar rats received bilateral infusions (1 μL per side) of saline, 8-OH-DPAT (5-HT1 agonist; 10 nmol), WAY100135 (5-HT1 antagonist; 0.9 nmol), ketanserine (5-HT 2 antagonist; 10 nmol), or fluoxetine (serotonin reuptake inhibitor; 1.6 nmol) into the BLA and were submitted to PMDAT training session 15 min later. In the test, 24 hr later, animals were re-exposed to the apparatus without the infusion of drugs, and aversive memory was evaluated. (a) 8-OH-DPAT did not affect memory or anxiety, but impaired avoidance behavior toward the aversive arm during training; (b) fluoxetine, WAY100135 and ketanserin impaired memory formation; (c) ketanserin decreased anxiety-like behavior; and (d) none of the treatments induced motor changes. The results showed that an increase in serotonin (5-HT) availability or the blockade of 5HT1A and 5HT2A BLA receptors impaired aversive memory formation. However, only 5HT2A receptor antagonism induced anxiolytic effects. Thus, both memory and anxiety-like behavior can be modified by changes in serotonergic transmission in the basolateral amygdala, but the effects on both phenomena seem to be mediated by different mechanisms related to serotonergic transmission. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Cannabidiol Recovers Dopaminergic Neuronal Damage Induced by Reserpine or α-synuclein in Caenorhabditis elegans

Progressive neurodegenerative disorders such as Parkinson Disease (PD) lack curative or long-term treatments. At the same time, the increase of the worldwide elderly population and, consequently, the extension in the prevalence of age-related diseases have promoted research interest in neurodegenerative disorders. Caenorhabditis elegans is a free-living nematode widely used as an animal model in studies of human diseases. Here we evaluated cannabidiol (CBD) as a possible neuroprotective compound in PD using the C. elegans models exposed to reserpine. Our results demonstrated that CBD reversed the reserpine-induced locomotor alterations and this response was independent of the NPR-19 receptors, an orthologous receptor for central cannabinoid receptor type 1. Morphological alterations of cephalic sensilla (CEP) dopaminergic neurons indicated that CBD also protects neurons from reserpine-induced degeneration. That is, CBD attenuates the reserpine-induced increase of worms with shrunken soma and dendrites loss, increasing the number of worms with intact CEP neurons. Finally, we found that CBD also reduced ROS formation and α-syn protein accumulation in mutant worms. Our findings collectively provide new evidence that CBD acts as neuroprotector in dopaminergic neurons, reducing neurotoxicity and α-syn accumulation highlighting its potential in the treatment of PD.

Sex differences in the acute ethanol effects on object recognition memory: influence of estrous cycle

Effects of acute ethanol (EtOH) on memory depend on several factors, including type of behavioral task. Sex differences in EtOH effects have been reported in humans and animals, and recognition memory can be influenced by circulating sex hormones. The aim of this study was to investigate the influence of sex and estrous cycle in the acute effects of EtOH on novel object recognition memory in rats. Male and female Wistar rats were part of one of the groups: control, 0.6-g/kg EtOH and 1.8-g/kg EtOH (administered intraperitoneally before the training session). The estrous cycle was evaluated by vaginal smear. The task was conducted in an open field arena. During training, animals were exposed to two identical objects, and test sessions were performed 1 h (short-term) and 24 h (long-term) later. One of the objects was changed in each test. Increased novel object exploration was shown by male and female controls in the short- and long-term tests, respectively. In the short-term test, females did not show preference for the novel object, and EtOH 1.8 g/kg impaired performance in males. In the long-term test, both sexes showed object discrimination, and 1.8-g/kg EtOH reduced preference for the new object in male rats. The phase of the cycle, the performance on proestrus was worse compared with other phases, and EtOH failed to impair performance mainly on estrous. In conclusion, while male rats displayed ethanol-induced recognition memory deficit, female rats were unaffected by EtOH impairing effects. In addition, the performance of female rats was influenced by the estrous cycle phases.

Changes in the mesocorticolimbic pathway after low dose reserpine-treatment in Wistar and Spontaneously Hypertensive Rats (SHR): Implications for cognitive deficits in a progressive animal model for Parkinson's disease

Reserpine (RES) is an irreversible inhibitor of VMAT2 used to study Parkinson's disease (PD) and screening for antiparkinsonian treatments in rodents. Recently, the repeated treatment with a low dose of reserpine was proposed as a model capable of emulating progressive neurochemical, motor and non-motor impairments in PD. Conversely, compared to Wistar rats, Spontaneously Hypertensive Rats (SHR) are resistant to motor changes induced by repeated treatment with a low dose of RES. However, such resistance has not yet been investigated for RES-induced non-motor impairments. We aimed to assess whether SHR would have differential susceptibility to the object recognition deficit induced by repeated low-dose reserpine treatment. We submitted male Wistar and SHR rats to repeated RES treatment (15 s.c. injections of 0.1 mg/kg, every other day) and assessed object memory acquisition and retrieval 48 h after the 6^th RES injection (immediately before the appearance of motor impairments). Only RES Wistar rats displayed memory impairment after reserpine treatment. On the other hand, untreated SHR rats displayed object recognition memory deficit, but RES treatment restored such deficits. We also performed immunohistochemistry for tyrosine hydroxylase (TH) and α-synuclein (α-syn) 48 h after the last RES injection. In a different set of animals submitted to the same treatment, we quantified DA, 5-HT and products of lipid peroxidation in the prefrontal cortex (PFC) and hippocampus (HPC). SHR presented increased constitutive levels of DA in the PFC and reduced immunoreactivity to TH in the medial PFC and dorsal HPC. Corroborating the behavioral findings, RES treatment restored those constitutive alterations in SHR. These findings indicate that the neurochemical, molecular and genetic differences in the SHR strain are potentially relevant targets to the study of susceptibility to diseases related to dopaminergic alterations.

Eplingiella fruticosa leaf essential oil complexed with β-cyclodextrin produces a superior neuroprotective and behavioral profile in a mice model of Parkinson's disease

Evidence indicates that oxidative stress has an important role in the onset and progression of Parkinson's disease (PD). Antioxidant agents from natural products have shown neuroprotective effects in animal models of PD. Eplingiella fruticosa is an aromatic and medicinal plant of the Lamiaceae family that include culinary herbs. The essential oil (EPL) has anti-inflammatory and antioxidant activities. Cyclodextrins are used to enhances pharmacological profile of essential oil. We obtained the EPL from leaves and complexed with β-cyclodextrin (EPL-βCD). Phytochemical analysis showed as main constituents: β-caryophyllene, bicyclogermacrene and 1,8-cineole. We evaluated the effects of EPL and EPL-βCD (5 mg/kg, p.o. for 40 days) on male mice submitted to the progressive reserpine PD model. Behavioral evaluations, lipid peroxidation quantification and immunohistochemistry for tyrosine hydroxylase were conducted. EPL delayed the onset of catalepsy and decreased membrane lipid peroxides levels in the striatum. EPL-βCD also delayed the onset of catalepsy, reduced the frequency of oral diskynesia, restored memory deficit, produced anxiolytic activity and protected against dopaminergic depletion in the striatum and SNpc. These findings showed that EPL has a potential neuroprotective effect in a progressive PD animal model. Further, EPL-βCD enhanced this protective effects, suggesting a novel therapeutic approach to ameliorate the symptoms of PD.

Spontaneously Hypertensive Rats (SHR) Are Resistant to a Reserpine-Induced Progressive Model of Parkinson's Disease: Differences in Motor Behavior, Tyrosine Hydroxylase and α-Synuclein Expression

Reserpine is an irreversible inhibitor of vesicular monoamine transporter-2 (VMAT2) used to study Parkinson’s disease (PD) and screening for antiparkinsonian treatments in rodents. Recently, the repeated treatment with a low-dose of reserpine was proposed as a progressive model of PD. Rats under this treatment show progressive catalepsy behavior, oral movements and spontaneous motor activity decrement. In parallel, compared to Wistar rats, spontaneously hypertensive rats (SHR) are resistant to acute reserpine-induced oral dyskinesia. We aimed to assess whether SHR would present differential susceptibility to repeated reserpine-induced deficits in the progressive model of PD. Male Wistar and SHR rats were administered 15 subcutaneously (s.c.) injections of reserpine (0.1 mg/kg) or vehicle, every other day and motor activity was assessed by the catalepsy, oral movements and open field tests. Only reserpine-treated Wistar rats presented increased latency to step down in the catalepsy test and impaired spontaneous activity in the open field. On the other hand, there was an increase in oral movements in both reserpine-treated strains, although with reduced magnitude and latency to instauration in SHR. After a 15-day withdrawn period, both strains recovered from motor impairment, but SHR animals expressed reduced latencies to reach control levels. Finally, we performed immunohistochemistry for tyrosine hydroxylase (TH) and α-synuclein (α-syn) 48 h after the last injection or 15 days after withdrawn. Reserpine-treated animals presented a reduction in TH and an increase in α-syn immunoreactivity in the substantia nigra and dorsal striatum (dSTR), which were both recovered after 15 days of withdraw. Furthermore, SHR rats were resistant to reserpine-induced TH decrement in the substantia nigra, and presented reduced immunoreactivity to α-syn in the dSTR relative to Wistar rats, irrespective of treatment. This effect was accompanied by increase of malondaldhyde (MDA) in the striatum of reserpine-treated Wistar rats, while SHR presented reduced MDA in both control and reserpine conditions relative to Wistar strain. In conclusion, the current results show that SHR are resilient to motor and neurochemical impairments induced by the repeated low-dose reserpine protocol. These findings indicate that the neurochemical, molecular and genetic differences in the SHR strain are potential relevant targets to the study of susceptibility to PD.