Influence of various intermittent fasting regimens on body weight and glycemic control in streptozotocin-induced diabetic rats

OBJECTIVE

This study aims to compare the effects of various intermittent fasting (IF) regimens, i.e., time-restricted fasting (TRF), alternate day fasting (ADF), and periodic fasting (PF) on body weight, glycemic control and associated metabolic parameters in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Sixty male Sprague-Dawley rats (aged 3 months) were randomly assigned to the normal control (NC), diabetic control (DC), TRF, ADF, and PF groups. Type 2 diabetes was induced in all groups, except for the NC group, by intramuscular administration of streptozotocin (55 mg/kg). The IF interventions were administered for 6 weeks.

RESULTS

The rats in all the groups, except for the NC group, exhibited significant weight loss (31.4%, 46.4%, 31.0%, and 33.9% in the DC, TRF, ADF, and PF groups, respectively). The fasting blood glucose levels decreased to varying degrees, with the PF group showing the most significant decrease (77.0%), followed by the ADF (55.0%) and TRF (32.2%) groups. The plasma insulin levels were significantly lower in the experimental groups than in the NC group, but no significant effects were observed on the lipid profile.

CONCLUSIONS

The study findings indicate that while the IF protocols led to body weight loss, they exhibited varying effects on glycemic control and other metabolic parameters.

Mechanisms underlying cognitive impairment induced by prenatal cannabinoid exposure: a literature review

Human and animal studies have revealed that prenatal cannabinoid exposure alters fetal brain development and leads to persistent impairment in the cognitive function of offspring. However, the mechanism underlying the effect of prenatal cannabinoid exposure on cognitive function in offspring is still not fully understood. Therefore, the goal of this literature review is to discuss the published studies on the mechanisms underlying the effects of prenatal cannabinoid exposure on cognitive impairment. The articles used in this prenatal cannabinoid exposure review were retrieved by electronic search of the Medline database for literature describing human and animal models of prenatal cannabinoid exposure from 2006 to 2022. The findings from the studies reviewed revealed that the cognitive impairment associated with prenatal cannabinoid exposure is caused by alterations in the expression and function of endocannabinoid receptor 1 (CB1R), decreased glutamate transmission, reduced neurogenesis, alterations in protein kinase B (PKB/Akt) and extracellular signal‑regulated kinase 1 and 2 (ERK1/2) activity, and increased mitochondrial function in the hippocampus, cortex, and cerebellum. This review briefly touches upon the currently available measurement and prevention methods and their limitations.

Ciproxifan attenuates the memory impairment induced by lipopolysaccharide through modulation of cholinergic transmission in the mouse brain

OBJECTIVE

We investigated the protective effect of ciproxifan on lipopolysaccharide (LPS)-induced memory impairment by altering the cholinergic system in a mouse model.

MATERIALS AND METHODS

Groups of mice were given ciproxifan (1 or 3 mg/kg, p.o.) for 30 days. Neurotoxicity was induced with four doses of LPS (250 µg/kg, i.p.) from day-22 to day-25 of drug treatment in three groups. Then, mice were subjected to behavioral assessments using tests [elevated plus maze (EPM), novel object recognition (NOR), and Y-maze]. Also, brain tissues were collected for estimation of cholinergic transmission [acetylcholine (ACh) and acetylcholinesterase (AChE) levels].

RESULTS

Ciproxifan could rescue the memory impairment caused by LPS by shortening the transfer latency in the EPM test, increasing the time spent to explore a novel object and increasing the Discrimination Index in the NOR test and increasing the number of entries to the novel arm and duration of time spent in the novel arm in the Y-maze test. Ciproxifan increased the levels of ACh by decreasing AChE activity in LPS-treated mice.

CONCLUSIONS

Ciproxifan treatment can improve memory impairment in mice by increasing ACh levels and decreasing AChE levels.

Mechanisms underlying cognitive impairment induced by prenatal caffeine exposure

OBJECTIVE

Caffeine is one of the most commonly used stimulants among pregnant women. Human and animal studies have shown that prenatal caffeine exposure affects fetal brain development and results in persistent cognitive deficits in offspring. Studies have found that caffeine consumption during pregnancy may alter many activities that are ultimately associated with cognitive dysfunction in offspring. Despite these important findings, there is a fundamental gap in understanding the mechanism underlying cognitive impairment due to prenatal caffeine exposure. Filling this knowledge gap would provide further insights into caffeine-mediated cognitive dysfunction. The objective of this review was to evaluate the findings of studies showing that prenatal caffeine exposure induces cognitive dysfunction and the potential underlying mechanisms.

Co-administration of imipramine and doxorubicin reduces the survival rate and body weight of mice

OBJECTIVE

Doxorubicin (DOX) is a chemotherapeutic agent widely used to treat cancers, particularly breast cancer. DOX has side effects, including cardiotoxicity, hepatotoxicity, and nephrotoxicity. Imipramine is an antidepressant that increases the release of neurotransmitters. This study aimed to investigate the effect of co-administration of imipramine and DOX on DOX-induced toxicity.

MATERIALS AND METHODS

Forty female mice (10-12-weeks-old, 30-38 g) were divided into four groups (n = 10 per group). The animals in the control group received a single-dose saline injection. The animals in the DOX group received a single dose of DOX (20 mg/kg) by intraperitoneal (i.p.) injection. The animals in the imipramine group received the drug daily in their drinking water (0.13 mg/mL) for 9 days, starting 1 day before the DOX injection received by the DOX group. The animals in the combination group (DOX+imipramine) received a single dose of DOX (20 mg/kg, i.p. injection), and a daily dose of imipramine in their drinking water (0.13 mg/mL) for 9 days starting 1 day before the DOX injection. The animals were observed daily to record mortality, and their body weights were recorded every alternate day.

RESULTS

DOX treatment increased the rate of mortality compared with that for control animals. Imipramine co-administration with DOX increased the rate of mortality significantly (p < 0.05) compared with DOX treatment alone. The mortality rate in both the control and imipramine-treatment groups was zero. DOX co-administered with imipramine resulted in significantly reduced body weight compared with control animals.

CONCLUSIONS

The combination of DOX and imipramine reduced the survival rate of female mice, suggesting that imipramine increases the toxic effects of DOX.

Varenicline enhances the survival of doxorubicin-treated mice

OBJECTIVE

Doxorubicin (DOX) is widely used to treat various types of cancer. However, DOX treatment increases oxidative stress and causes other undesirable effects, such as cardiotoxicity, cognitive impairment, and death. Nicotine has been shown to inhibit DOX-induced cytotoxicity in vitro by activating nicotinic acetylcholine receptors. This study aimed to investigate whether combined treatment with varenicline, a partial agonist of nicotinic acetylcholine receptors, increased the survival rate of DOX-treated mice.

MATERIALS AND METHODS

Forty male albino mice were divided into four groups of 10. Control-group mice received a single intraperitoneal (i.p.) injection of 0.9% saline. The DOX group received a single dose of DOX (20 mg/kg body weight, i.p.). The varenicline group received varenicline daily in their drinking water at 0.1 mg/mL. The DOX+varenicline group received a single dose of DOX (20 mg/kg body weight, i.p.) and daily administration of varenicline in their drinking water (0.1 mg/mL). Mice were observed daily to evaluate the survival rate, and their body weight was recorded on alternate days.

RESULTS

All mice treated only with DOX died within 8 days. Co-administration of varenicline with DOX slightly improved the survival time and rate compared with the DOX-only group.

CONCLUSIONS

Combined treatment with varenicline and DOX may be useful for improving survival relative to treatment with DOX alone. This may be because varenicline is an α7-nicotinic acetylcholine receptor agonist; however, further research into its precise mechanism of action is required.

Role of the purinergic P2Y2 receptor in hippocampal function in mice

OBJECTIVE

The aim of this study is to investigate the role of the purinergic P2Y2 receptor in learning and memory processes.

MATERIALS AND METHODS

Behavioral, electrophysiological, and biochemical tests of memory function were conducted in P2Y2 receptor knockout (P2Y2R-KO) mice, and the findings were compared to those of wild-type mice with the help of unpaired Student's t-test.

RESULTS

The findings of the behavioral Y-maze test showed that the P2Y2R-KO mice had impaired memory and cognitive function. Electrophysiological studies on paired-pulse facilitation showed that glutamate release was higher in the P2Y2R-KO mice than in the WT mice. Furthermore, PCR and Western blot analysis revealed that the mRNA and protein expression of acetylcholinesterase E (AChE) and alpha-7 nicotinic acetylcholine receptors (α7 nAChRs) were increased in the hippocampus of P2Y2R-KO mice.

CONCLUSIONS

The findings of this study indicate that P2Y2 receptors are important regulators of both glutamatergic and cholinergic systems in the hippocampus.

Metformin administration increases the survival rate of doxorubicin-treated mice

Background: The chemotherapeutic agent doxorubicin (DOX), an anthracycline broadly used to treat different types of cancers, induces several side effects, including cardiotoxicity, hepatotoxicity, and nephrotoxicity, in a time- and dose-dependent manner. Metformin (MET) is an antidiabetic drug used as a first-line treatment for type-2 diabetes, and is reported to work against various various drug-induced toxicities. This study aimed to investigate whether the administration of MET prophylactically suppresses DOX-induced toxicity, and prolongs the survival following DOX treatment. Methods: Fifty mice were divided into four groups, and each group received different treatments. The animals in the control group received a single injection of saline. The animals in the DOX group received a single dose of DOX (25 mg/kg). The animals in the MET group received MET on a daily basis. The animals in the DOX+MET group received only a single dose of DOX and daily doses of MET. The animals were observed on a daily basis for determining their body weight and evaluating the survival rate of the four study groups. Results: DOX accelerated the mortality rate of the animals in the DOX-treated group. Co-administration of MET and DOX increased the survival rate of the mice. Conclusion: The results of this study demonstrated that the administration of MET can reduce DOX-induced toxicity and increase the survival rate among chemotherapy-treated mice.

Candidate mechanisms of caffeine improving memory dysfunction

Caffeine is the most common psycho-stimulant that is broadly known to cause peripheral effects. Caffeine is well known as an adenosine receptor antagonist. Adenosine receptors are present in all areas of the brain, which makes caffeine's effects very prevalent. The main goal of this review is to summarize recent studies that are investigating the mechanism of action of acute and chronic caffeine treatment of to alleviate the cognitive deficits and synaptic plasticity. This review discusses the effect of caffeine on the brain functions including learning and memory, and synaptic plasticity in case of various diseases.