PET Imaging of the Interaction between Adenosine A2A and Dopamine D2 Receptors in Animal Models of Brain Diseases

This thesis focuses on the antagonistic interactions between adenosine and dopamine in living mammals, mediated through adenosine A2A and dopamine D2 receptors. These interactions are crucial in locomotor activation, goal-directed behavior, motor control, and reward-related behavior. The reciprocal interactions primarily occur in specific neurons and astrocytes within the striatal region and nucleus accumbens. In striatal membrane preparations, adenosine negatively affects the affinity and signal transduction of D2 receptors by interacting with A2A receptors. The proximity of A2A and D2 receptors in biomembranes allows them to co-aggregate, co-internalize, and co-desensitize. They form heteromeric complexes, contributing to the allosteric receptor-receptor interactions responsible for the antagonistic effects observed between adenosine and dopamine. These interactions have implications for treating various neurological and psychiatric disorders such as Parkinson's disease, schizophrenia, substance abuse, and attention deficit hyperactivity disorder. Understanding the dynamic equilibrium between A2A-D2 receptor heteromers and homodimers in the brain is an area of ongoing research. Positron emission tomography (PET) with suitable ligands can provide valuable in-vivo information about receptor crosstalk in living organisms. The development of novel imaging agents, including hetero-bivalent ligands, holds promise for investigating and visualizing A2A-D2 receptor interactions. Exploring the complex dynamics of these receptor interactions can pave the way for innovative therapeutic strategies and imaging techniques to better understand and treat neurological and psychiatric conditions

Painless labour: attitude and awareness amongst pregnant women

Background: Labour pain has been described as most severe pain experienced by a female. Labour analgesia is widely practiced in developed countries. Many labour analgesic methods have been introduced to make delivery a pleasurable moment in a women’s life.Methods: This prospective study was performed at the Department of Obstetrics and Gynaecology, Indira Gandhi Institute of Medical Sciences, Patna, India after getting permission from institute ethical committee. 100 pregnant females attending the antenatal clinic were interviewed in their mother language. Information was collected on a questionnaire after an informed consent. The aim of the study was to assess the knowledge, desire and acceptability of pregnant women regarding painless labour.Results: The mean age of the women in the study was 24.98years.56% of women in the study were primigravida whereas 44% were multigravida.66% women belonged to urban area while 34% were from rural area. 10% were illiterate, 35% were educated upto secondary education and 55% were having higher education. Only 24% of the women were having knowledge about painless labour however 87% female were having positive attitude towards epidural analgesia. The correlation between the educational status and knowledge about painless labour was not statistically significant (p0.949). The knowledge and attitude of women regarding painless labour was statistically significant with p value of 0.00001.Conclusions: There is lack of knowledge about labour analgesia among women. Obstetrician and anaesthetist should educate women regarding painless labour. Labour analgesia is standard of care in obstetrics and should be provided to all parturient

CRITICAL REVIEW ON DESIGN OF ROLLING PROCESS

Rolling is one of the important forming processes used in steel industry. During rolling process because of overdraft and poor die design, cracks and breakage of rolls takes place, leading to shutdown of rolling mill. There is a need for proper deign of rolling dies based on work piece material. In the present paper design methodologies followed by various researchers are presented. Review on works related to Finite Element Analysis (FEA) methods and material selection is carried out and presented.

Adenosarcoma of uterus in mother and mucinous carcinoma of breast in daughter: a rare case study

Adenosarcoma is an infrequent malignancy which consists of benign glandular epithelium and malignant mesenchymal component. We report a 63-year-old woman diagnosed with adenosarcoma with sarcomatous overgrowth of the uterine corpus, with history of mucinous carcinoma of the breast in her daughter. Although endometrial and breast cancers share few similar hormonal, reproductive and genetic risk factors, the association of endometrial cancer with breast carcinoma is not well established. 63 years old, P4L4, postmenopausal lady presented to our hospital with post-menopausal spotting, foul smelling vaginal discharge and pain abdomen for 1 week. After evaluation she underwent total abdominal hysterectomy with bilateral salpingo-oopherectomy. Intraoperatively, a pedunculated fundal polyp measuring 6×7 cm distending the uterine cavity was noted. Post-operative histopathology examination was reported as adenosarcoma with sarcomatoid overgrowth of the uterine cavity. Immunohistochemistry revealed CK7 (epithelium (+), Vimentin (+), cluster of differentiation 10 (CD10) (+) and, Wilms tumor 1 (-). The possible association between these two conditions, adenosarcoma of uterus in mother and mucinous carcinoma of breast in daughter is explored and presented in this case report

Allosteric Interactions between Adenosine A2A and Dopamine D2 Receptors in Heteromeric Complexes:Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging

Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A2A and dopamine D2 receptors (R). Stimulation of A2AR inhibits and blockade of A2AR enhances D2R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D2R via its interaction with A2AR. Reciprocal A2AR/D2R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A2AR and D2R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A2AR/D2R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A2AR/D2R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review

Maternal infection during pregnancy aggravates the behavioral response to an immune challenge during adolescence in female rats

Prenatal and early postnatal infection have been associated with changes in microglial activity and the development of psychiatric disorders. Here, we investigated the effect of prenatal immune activation and postnatal immune challenge, alone and combined, on behavior and microglial cell density in female Wistar rats. Pregnant rats were injected with poly I:C to induce a maternal immune activation (MIA). Their female offspring were subsequently exposed to a lipopolysaccharide (LPS) immune challenge during adolescence. Anhedonia, social behavior, anxiety, locomotion, and working memory were measured with the sucrose preference, social interaction, open field, elevated-plus maze, and Y-maze test, respectively. Microglia cell density was quantified by counting the number of Iba-1 positive cells in the brain cortex. Female MIA offspring were more susceptible to the LPS immune challenge during adolescence than control offspring as demonstrated by a more pronounced reduction in sucrose preference and body weight on the days following the LPS immune challenge. Furthermore, only the rats exposed to both MIA and LPS showed long-lasting changes in social behavior and locomotion. Conversely, the combination MIA and LPS prevented the anxiety induced by MIA alone during adulthood. MIA, LPS, or their combination did not change microglial cell density in the parietal and frontal cortex of adult rats. The results of our study suggest that the maternal immune activation during pregnancy aggravates the response to an immune challenge during adolescence in female rats.</p

Impact of an Adenosine A2A Receptor Agonist and Antagonist on Binding of the Dopamine D2 Receptor Ligand [11C]raclopride in the Rodent Striatum

Adenosine A2A and dopamine D2 receptors in the basal ganglia form heterotetrameric structures that are involved in the regulation of motor activity and neuropsychiatric functions. The present study examines the A2A receptor-mediated modulation of D2 receptor binding in vivo using positron emission tomography (PET) with the D2 antagonist tracer [11C]raclopride. Healthy male Wistar rats (n = 8) were scanned (60 min dynamic scan) with [11C]raclopride at baseline and 7 days later following an acute administration of the A2A agonist CGS21680 (1 mg/kg), using a MicroPET Focus-220 camera. Nondisplaceable binding potential (BPND) values were calculated using a simplified reference tissue model (SRTM), with cerebellum as the reference tissue. SRTM analysis did not show any significant changes in [11C]raclopride BPND (p = 0.102) in striatum after CGS21680 administration compared to the baseline. As CGS21680 strongly affects hemodynamics, we also used arterial blood sampling and a metabolite-corrected plasma input function for compartment modeling using the reversible two-tissue compartment model (2TCM) to obtain the BPND from the k3/k4 ratio and from the striatum/cerebellum volume of distribution ratio (DVR) in a second group of animals. These rats underwent dynamic [11C]raclopride scans after pretreatment with a vehicle (n = 5), a single dose of CGS21680 (1 mg/kg, n = 5), or a single dose of the A2A antagonist KW6002 (1 mg/kg, n = 5). The parent fraction in plasma was significantly higher in the CGS21680-treated group (p = 0.0001) compared to the vehicle-treated group. GCS21680 administration significantly reduced the striatal k3/k4 ratio (p < 0.01), but k3 and k4 estimates may be less reliable. The BPND (DVR-1) decreased from 1.963 ± 0.27 in the vehicle-treated group to 1.53 ± 0.55 (p = 0.080) or 1.961 ± 0.11 (p = 0.993) after the administration of CGS21680 or KW6002, respectively. Our study suggests that the A2A agonist CGS21680, but not the antagonist KW6002, may reduce the D2 receptor availability in the striatum

Gradient Expression of Transcription Factor Imposes a Boundary on Organ Regeneration Potential in Plants

A wide variety of multicellular organisms across the kingdoms display remarkable ability to restore their tissues or organs when they suffer damage. However, the ability to repair damage is not uniformly distributed throughout body parts. Here, we unravel the elusive mechanistic basis of boundaries on organ regeneration potential using root tip resection as a model and show that the dosage of gradient-expressed PLT2 transcription factor is the underlying cause. While transient downregulation of PLT2 in distinct set of plt mutant backgrounds renders meri-stematic cells incapable of regeneration, forced expression of PLT2 acts through auto-activation to confer regeneration potential to the cells undergoing differentiation. Surprisingly, sustained exposure to nuclear PLT2, beyond a threshold, leads to reduction of regeneration potential despite giving rise to longer meristem. Our studies reveal dosage-dependent role of gradient-expressed PLT2 in root tip regeneration and uncouple the size of an organ from its regeneration potential.Peer reviewe

Allosteric Interactions between Adenosine A2A and Dopamine D2 Receptors in Heteromeric Complexes: Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging

Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A2A and dopamine D2 receptors (R). Stimulation of A2AR inhibits and blockade of A2AR enhances D2R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D2R via its interaction with A2AR. Reciprocal A2AR/D2R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A2AR and D2R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A2AR/D2R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A2AR/D2R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review