Noradrenergic inputs from locus coeruleus to posterior ventral tegmental area are essential to support ethanol reinforcement

2015 ◽  
Vol 22 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Gajanan P. Shelkar ◽  
Santosh Kumar ◽  
Praful S. Singru ◽  
Nishikant K. Subhedar ◽  
Dadasaheb M. Kokare
2017 ◽  
Vol 118 (3) ◽  
pp. 1501-1514 ◽  
Author(s):  
Tahseen J. Karim ◽  
Cruz Reyes-Vazquez ◽  
Nachum Dafny

Methylphenidate (MPD), also known as Ritalin, is a psychostimulant used to treat attention deficit hyperactivity disorder. However, it is increasingly being misused by normal adolescents for recreation and academic advantage. Therefore, it is important to elucidate the behavioral and neurophysiological effects of MPD in normal subjects. MPD inhibits the reuptake of catecholamines, mainly found in the ventral tegmental area (VTA) and locus coeruleus (LC). The VTA and LC normally mediate attention, motivation, and drug reward behaviors. Selective neuronal connections between the VTA and LC have been identified implicating regular interaction between the structures. The objective of this study was to compare the neuronal responses of the VTA and LC to MPD in normal adolescent rats. Animals were implanted with permanent electrodes in the VTA and LC, and neuronal units were recorded following acute and repetitive (chronic) saline or 0.6, 2.5, or 10.0 mg/kg MPD exposure. Animals displayed either behavioral sensitization or tolerance to all three doses of MPD. Acute MPD exposure elicited excitation in the majority of all VTA and LC units. Chronic MPD exposure elicited a further increase in VTA and LC neuronal activity in animals exhibiting behavioral sensitization and an attenuation in VTA and LC neuronal activity in animals exhibiting behavioral tolerance, demonstrating neurophysiological sensitization and tolerance, respectively. The similar pattern in VTA and LC unit activity suggests that the two structures are linked in their response to MPD. These results may help determine the exact mechanism of action of MPD, resulting in optimized treatment of patients. NEW & NOTEWORTHY The same dose of 0.6, 2.5, and 10 mg/kg methylphenidate (MPD) elicits either behavioral sensitization or tolerance in adolescent rats. There is a direct correlation between the ventral tegmental area (VTA) and locus coeruleus (LC) neuronal response to chronic MPD exposure. Both the VTA and LC are involved in the behavioral and neurophysiological effects of chronic MPD.


2021 ◽  
Vol 13 ◽  
Author(s):  
Jiao Liu ◽  
Jing Tao ◽  
Rui Xia ◽  
Moyi Li ◽  
Maomao Huang ◽  
...  

Mild cognitive impairment (MCI) is a common global health problem. Recently, the potential of mind-body intervention for MCI has drawn the interest of investigators. This study aims to comparatively explore the modulation effect of Baduanjin, a popular mind-body exercise, and physical exercise on the cognitive function, as well as the norepinephrine and dopamine systems using the resting state functional connectivity (rsFC) method in patients with MCI. 69 patients were randomized to the Baduanjin, brisk walking, or healthy education control group for 6 months. The Montreal Cognitive Assessment (MoCA) and magnetic resonance imaging (MRI) scans were applied at baseline and at the end of the experiment. Results showed that (1) compared to the brisk walking, the Baduanjin significantly increased MoCA scores; (2) Baduanjin significantly increased the right locus coeruleus (LC) and left ventral tegmental area (VTA) rsFC with the right insula and right amygdala compared to that of the control group; and the right anterior cingulate cortex (ACC) compared to that of the brisk walking group; (3) the increased right LC-right insula rsFC and right LC-right ACC rsFC were significantly associated with the corresponding MoCA score after 6-months of intervention; (4) both exercise groups experienced an increased effective connectivity from the right ACC to the left VTA compared to the control group; and (5) Baduanjin group experienced an increase in gray matter volume in the right ACC compared to the control group. Our results suggest that Baduanjin can significantly modulate intrinsic functional connectivity and the influence of the norepinephrine (LC) and dopamine (VTA) systems. These findings may shed light on the mechanisms of mind-body intervention and aid the development of new treatments for MCI.


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