Effect of chronic nicotine administration on the anterior cingulate cortex (area 24a) of adult albino rats

The present study was conducted to clarify the role of the anterior cingulate cortex (ACCX) in acupuncture analgesia. Experiments were performed on 35 female Wistar albino rats weighing about 300 g. Single unit recordings were made from ACCX neurons with a tungsten microelectrode. Descending ACCX neurons were identified by antidromic activation from electrical shocks applied to the ventral part of the ipsilateral PAG through a concentric needle electrode. Cathodal electroacupuncture stimulation of Ho-Ku (0.1 ms in duration, 45 Hz) for 15 min was done by inserting stainless steel needles bilaterally. An anodal silver-plate electrode (30 mm × 30 mm ) was placed on the center of the abdomen. Naloxone (1.0 mg/kg, i.v.) was used to test whether changes of ACCX activities were induced by the endogenous opioid system. Data were collected from a total of 73 ACCX neurons. Forty-seven neurons had descending projection to the PAG, and the other 26 had no projections to the PAG. A majority of descending ACCX neurons were inhibited by electroacupuncture stimulation. By contrast, non-projection ACCX neurons were mainly unaffected by electroacupuncture. Naloxone did not reverse acupuncture effects on the changes of ACCX neuronal activities. Acupuncture stimulation had predominantly inhibitory effects on the activities of descending ACCX neurons. Since the functional connection between ACCX and PAG is inhibitory, electroacupuncture caused disinhibition of PAG neurons, whose activity is closely related to descending antinociception to the spinal cord. This disinhibitory effect elicited by acupuncture stimulation is thought to play a significant role in acupuncture analgesia.

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The impacts of actual and perceived nicotine administration on insula functional connectivity with the anterior cingulate cortex and nucleus accumbens

Journal of Psychopharmacology ◽

10.1177/0269881119872205 ◽

2019 ◽

Vol 33 (12) ◽

pp. 1600-1609 ◽

Cited By ~ 3

Author(s):

Robin N Perry ◽

Hera E Schlagintweit ◽

Christine Darredeau ◽

Carl Helmick ◽

Aaron J Newman ◽

...

Keyword(s):

Nucleus Accumbens ◽

Functional Connectivity ◽

Anterior Cingulate Cortex ◽

Resting State ◽

Cingulate Cortex ◽

Anterior Insula ◽

Anterior Cingulate ◽

Resting State Functional Connectivity ◽

Dorsal Anterior Cingulate Cortex ◽

Nicotine Administration

Background: Changes in resting state functional connectivity between the insula and dorsal anterior cingulate cortex as well as between the insula and nucleus accumbens have been linked to nicotine withdrawal and/or administration. However, because many of nicotine’s effects in humans appear to depend, at least in part, on the belief that nicotine has been administered, the relative contribution of nicotine’s pharmacological actions to such effects requires clarification. Aims: The purpose of this study was to examine the impacts of perceived and actual nicotine administration on neural responses. Methods: Twenty-six smokers were randomly assigned to receive either a nicotine inhaler (4 mg deliverable) or a nicotine-free inhaler across two sessions. Inhaler content instructions (told nicotine vs told nicotine-free) differed across sessions. Resting state functional connectivity between sub-regions of the insula and the dorsal anterior cingulate cortex and nucleus accumbens was measured using magnetic resonance imaging before and after inhaler administration. Results: Both actual and perceived nicotine administration independently altered resting state functional connectivity between the anterior insula and the dorsal anterior cingulate cortex, with actual administration being associated with decreased resting state functional connectivity, and perceived administration with increased resting state functional connectivity. Actual nicotine administration also contralaterally reduced resting state functional connectivity between the anterior insula and nucleus accumbens, while reductions in resting state functional connectivity between the mid-insula and right nucleus accumbens were observed when nicotine was administered unexpectedly. Changes in resting state functional connectivity associated with actual or perceived nicotine administration were unrelated to changes in subjective withdrawal and craving. Changes in withdrawal and craving were however independently associated with resting state functional connectivity between the nucleus accumbens and insula. Conclusions: Our findings highlight the importance of considering non-pharmacological factors when examining drug mechanisms of action.

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Inactivation of the subcallosal anterior cingulate cortex Area 25 increases reward-related behaviour and motivation in the common marmoset

10.14293/s2199-1006.1.sor-.ppqujw6.v1 ◽

2020 ◽

Author(s):

Rana Banai Tizkar ◽

Laith Alexander ◽

Philip L.R. Gaskin ◽

Christian Wood ◽

Angela McCaskill Roberts

Keyword(s):

Anterior Cingulate Cortex ◽

Brain Area ◽

Preference Test ◽

Cardiovascular Responses ◽

Progressive Ratio ◽

Cingulate Cortex ◽

Common Marmoset ◽

Anterior Cingulate ◽

Cortex Area

Depression consists of a heterogenous set of symptoms such as low mood and blunted emotion known as anhedonia. A brain area extensively reported to be involved in depression is the subgenual anterior cingulate cortex area 25, which seems to be overactive in depression. Recently it has been shown that overactivation of area 25 in marmosets led to anticipatory and motivational anhedonia as measured by blunted cardiovascular responses and behavioural arousal in an appetitive Pavlovian task, and reduced willingness to work in a Progressive Ratio task respectively. In this study the role of area 25 in motivation was further investigated by inactivating this region by infusing GABA A/B agonists in cannulated marmosets on the progressive ratio task. We show that inactivation of area 25 increased total responses. However, there was also an increase in licking behaviour outside of reward delivery. A follow-up sucrose preference test showed that inactivating this brain area also led to an increase in sucrose consumption. Overall the findings indicate that area 25 inactivation increases motivation as measured by the increased breakpoint, but also promotes a consummatory behaviour. Dissecting the network related to these changes in both motivation and consummatory behaviour will be key to understanding the role of the subgenual cingulate cortex in mood disorders. We hypothesise that whilst the increased breakpoint may be related to subgenual interactions with the nucleus accumbens, increased consummatory licking may be related instead to interactions with the hypothalamus.

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