جستجوی مقالات مرتبط با کلیدواژه "social memory" در نشریات گروه "پزشکی"

Methamphetamine is one of the stimulant drugs that leads to the occurrence of cognitive and behavioral dysfunctions. Among the disorders that occur after methamphetamine abuse are learning and memory disorders as well as social interactions and anxiety. On the other hand, the function of sex steroids in the development of brain regions involved in reproduction has been the subject of extensive research over the years. In this context, testosterone plays an important role in neuronal and glial organization in prenatal and postnatal periods. Recent studies showed the effect of sex hormones on the nervous system and highlight the brain as a main target tissue for androgens. On the other hand, studies have shown that testosterone has neuroprotective effects against cognitive and behavioral disorders. Clinical manifestations of testosterone-related brain changes include cognitive impairments such as reduced memory efficiency related to the frontal cortex, as well as reduced long-term memory related to the hippocampus and other temporal regions of the midbrain. Androgens, especially testosterone, play an important role in memory function whereby the decrease and absence of testosterone leads to cognitive impairment and also neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Therefore, in this study, the role of testosterone hormone in social memory, novel object recognition memory, as well as anxiety-like behavior and brain edema induced by a neurotoxic regimen of methamphetamine were investigated.

This study was conducted on 48 gonadectomized rats in 6 groups including control groups, methamphetamine (6mg/kg), solvent (sesame oil), methamphetamine + testosterone (0.25mg /kg), methamphetamine + testosterone (0.5 mg/kg) and methamphetamine + testosterone (1 mg/kg) were performed. At first, mice were anesthetized and gonadectomy surgery was performed. After 2 weeks of recovery, the evaluation of social memory was done using the three-chamber social interaction test, and anxiety-like behavior index using the open field test. Finally, the animals were killed and the brain tissue was evaluated for brain edema.

The findings of the study showed that social memory was significantly impaired in rats that received methamphetamine compared to the control group (P<0.001). On the other hand, results showed that there was a significant increase in anxiety-like behaviors as well as brain edema in rats that received methamphetamine (P<0.001). Statistical analysis also showed that the administration of testosterone hormone was able to improve cognitive functions and reduce anxiety-like behaviors and brain edema caused by methamphetamine (P<0.05).

Overall, the present study suggests that the male sex hormone testosterone can be effective in improving behavioral disorders and anxiety, as well as brain edema caused by the administration of methamphetamine. Further research is needed to investigate the cellular and molecular mechanisms of the effects of this hormone.

Methamphetamine is a stimulant of the central nervous system, which is now increasingly abused. Long-term use of this psychoactive drug is associated with many cognitive disorders, including learning and memory impairment. Kisspeptin-13 is one of the endogenous neuropeptides, whose neuroprotective role on cognitive functions, especially memory, was investigated in several studies. In the present study, the role of kisspeptin-13 in mitigating social memory impairment induced by methamphetamine was investigated.

This experimental study was carried out on 40 adult male Wistar rats weighing (200-270 g). This study was conducted with the code of ethics (IR.MAZUMS..REC.1398.6037) at the Neuroscience Research Center of Mazandaran University of Medical Sciences. In this study, the animals were randomly divided into four groups: control, methamphetamine,kisspeptin-13+ methamphetamine, and kisspeptin-13 groups. First, pretreatment with kisspeptin-13 was done intraventricularly for three days at a dose of 1.5 µg/µL in the respective groups. Specifically, on the initial day, the subjects were given a dose of 1 mg/kg twice, with a 4-hour interval. On the following day, the dosage was raised to 2 mg/kg, and this incrementally increased on subsequent days throughout the week. Thus, on the third day, the dose was 3 mg/kg, on the fourth day, the dose was 4 mg/kg, and on the fifth, sixth, and seventh days, the doses were 5 mg/kg, 6 mg/kg, and 7 mg/kg, respectively. After the injections, the social interaction behavioral test evaluates social memory and sociability. This test was carried out in a three-chambered device for ten minutes in a rectangular space that was divided into three parts. In the side chambers, there were two wire chambers in which stranger and familiar rats were placed. On the test day, the time spent in each room was monitored.

The results of this investigation, which examined the effect of kisspeptin-13 on sociability and social memory in two stages, were as follows. The effect of kisspeptin -13 on sociability showed that the duration of exploration in the chamber where the first stranger mouse was placed was longer than the duration of exploration in the empty chamber in all experimental groups. Results indicated that sociability in these animals was not affected by the administration of methamphetamine, as well as kisspeptin -13, and all animals in the groups receiving the drug responded similarly to the control group. Statistical analysis regarding the effect of kisspeptin -13 on social memory showed that there is a significant statistical difference in the time spent for the first stranger mouse and the second stranger mouse, and the animals in the group receiving methamphetamine spent more time in social interaction with the first stranger mouse, which indicates damage to social memory, and the administration of kisspeptin -13 in animals receiving methamphetamine also failed to improve social memory. In the group receiving kisspeptin -13, social memory was not significantly different from the control group, which indicated that the administration of kisspeptin -13 alone does not lead to damage to social memory.

This study showed that methamphetamine can lead to serious impairment of social memory without causing a change in social interaction, and pretreatment with kisspeptin-13 could not compensate for the damage to social memory caused by the administration of methamphetamine.

Empathy is one of the special cognitive functions that play an important role in the evolution of social behaviors and the formation of social memory. Testosterone have neuroprotective effects against cognitive and behavioral disorders and may be very important in the development of social and cognitive behaviors. Therefore, this study investigated the role of testosterone hormone in social behaviors, novel object recognition memory, and anxiety-like behaviors in a rat model of empathic pain.

In this study, 32 gonadectomized male rats were divided into four groups: control, pain, observer + vehicle (castor oil), and observer + testosterone. The emotional pain experienced by a family member who received five formalin injections was socially transferred to the observing rat within the same family through observation. The observation groups received vehicle or testosterone before observing the suffering of mice. Then, social memory, novel object recognition memory, and anxiety-like behaviors were tested.

The results indicated that in the pain group, both social memory and novel object recognition memory were impaired compared to the control group, and anxiety-like behaviors were increased. Conversely, testosterone injection partially improved social memory and novel object recognition memory deficits, and reduced anxiety-like behaviors compared with the observer+vehicle group.

In conclusion, empathy causes anxious behavior and social and novel object recognition memory impairments. Furthermore, testosterone hormones can play a protective role against cognitive and behavioral damages caused by empathy in rats.