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Engel MG, Smith J, Mao K, Quipildor GF, Cui MH, Gulinello M, Branch CA, Gandy SE, Huffman DM. Evidence for preserved insulin responsiveness in the aging rat brain. GeroScience 2022; 44:2491-2508. [PMID: 35798912 PMCID: PMC9768080 DOI: 10.1007/s11357-022-00618-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/27/2022] [Indexed: 01/06/2023] Open
Abstract
Insulin appears to exert salutary effects in the central nervous system (CNS). Thus, brain insulin resistance has been proposed to play a role in brain aging and dementia but is conceptually complex and unlikely to fit classic definitions established in peripheral tissues. Thus, we sought to characterize brain insulin responsiveness in young (4-5 months) and old (24 months) FBN male rats using a diverse set of assays to determine the extent to which insulin effects in the CNS are impaired with age. When performing hyperinsulinemic-euglycemic clamps in rats, intracerebroventricular (ICV) infusion of insulin in old animals improved peripheral insulin sensitivity by nearly two-fold over old controls and comparable to young rats, suggesting preservation of this insulin-triggered response in aging per se (p < 0.05). We next used an imaging-based approach by comparing ICV vehicle versus insulin and performed resting state functional magnetic resonance imaging (rs-fMRI) to evaluate age- and insulin-related changes in network connectivity within the default mode network. In aging, lower connectivity between the mesial temporal (MT) region and other areas, as well as reduced MT signal complexity, was observed in old rats, which correlated with greater cognitive deficits in old. Despite these stark differences, ICV insulin failed to elicit any significant alteration to the BOLD signal in young rats, while a significant deviation of the BOLD signal was observed in older animals, characterized by augmentation in regions of the septal nucleus and hypothalamus, and reduction in thalamus and nucleus accumbens. In contrast, ex vivo stimulation of hippocampus with 10 nM insulin revealed increased Akt activation in young (p < 0.05), but not old rats. Despite similar circulating levels of insulin and IGF-1, cerebrospinal fluid concentrations of these ligands were reduced with age. Thus, these data highlight the complexity of capturing brain insulin action and demonstrate preserved or heightened brain responses to insulin with age, despite dampened canonical signaling, thereby suggesting impaired CNS input of these ligands may be a feature of reduced brain insulin action, providing further rationale for CNS replacement strategies.
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Affiliation(s)
- Matthew G Engel
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Institute for Aging Research, Albert Einstein College of Medicine, 1300 Morris Park Ave, Golding Building Room 201, BronxBronx, NY, 10461, USA
| | - Jeremy Smith
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Kai Mao
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Institute for Aging Research, Albert Einstein College of Medicine, 1300 Morris Park Ave, Golding Building Room 201, BronxBronx, NY, 10461, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Gabriela Farias Quipildor
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Institute for Aging Research, Albert Einstein College of Medicine, 1300 Morris Park Ave, Golding Building Room 201, BronxBronx, NY, 10461, USA
| | - Min-Hui Cui
- Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Maria Gulinello
- Dominick S. Purpura Department of Neuroscience, Behavioral Core Facility, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Craig A Branch
- Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Samuel E Gandy
- Department of Neurology and the Mount Sinai Center for Cognitive Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Psychiatry and the Mount Sinai Alzheimer's Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Derek M Huffman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Institute for Aging Research, Albert Einstein College of Medicine, 1300 Morris Park Ave, Golding Building Room 201, BronxBronx, NY, 10461, USA.
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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Easow Mathew M, Biswas T, Fahad S, Patnaik M. Modafinil for excessive daytime sleepiness. Hippokratia 2017. [DOI: 10.1002/14651858.cd010843.pub2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Manu Easow Mathew
- Christian Medical College; South Asian Cochrane Network & Center, Prof. BV Moses Center for Evidence-Informed Health Care and Health Policy; Carman Block II Floor CMC Campus, Bagayam Vellore Tamil Nadu India 632002
| | | | - Shabin Fahad
- Kasturba Medical College; Department of General Surgery; Light House Hill Road Mangalore Karnataka India 575001
| | - Mitali Patnaik
- Drexel University, College of Medicine, Hahnemann University Hospital; Department of Psychiatry; 230 North Broad Street Philadelphia Pennsylvania USA 19130
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Wittkampf LC, Arends J, Timmerman L, Lancel M. A review of modafinil and armodafinil as add-on therapy in antipsychotic-treated patients with schizophrenia. Ther Adv Psychopharmacol 2012; 2:115-25. [PMID: 23983964 PMCID: PMC3736916 DOI: 10.1177/2045125312441815] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Schizophrenia is characterized by reality distortion, psychomotor poverty and cognitive disturbances. These characteristics contribute to a lesser social functioning and lower quality of life in patients with schizophrenia. It has been suggested that modafinil and its isomer armodafinil as an add-on strategy to antipsychotic treatment in patients with schizophrenia may improve cognitive functioning, attenuate fatigue, inactiveness and other negative functions as well as weight gain. In this paper we review the literature relevant to the question of whether modafinil and armodafinil are beneficial as add-on therapy in antipsychotic-treated patients with schizophrenia. A total of 15 articles were included in this review; of the 15 articles, 10 were randomized controlled trials (RCTs). Evidence for the use of modafinil or armodafinil as add-on therapy to antipsychotic drugs to alleviate fatigue, sleepiness and inactivity is inconclusive. One cohort study and one out of two single-dose crossover RCTs in which modafinil addition was studied could demonstrate a positive effect. All five RCTs of modafinil (three RCTs) and armodafinil (two RCTs) addition with a longer study duration could not demonstrate a positive effect. With respect to cognitive disturbances, animal models of cognitive deficits show clear improvements with modafinil. In RCTs with a treatment duration of 4 weeks or more, however, no positive effect could be demonstrated on cognitive functioning with modafinil and armodafinil addition. Yet, four single-dose crossover RCTs of modafinil addition show significant positive effects on executive functioning, verbal memory span, visual memory, working memory, spatial planning, slowing in latency, impulse control and recognition of faces expressing sadness and sadness misattribution in the context of disgust recognition. The addition of modafinil or armodafinil to an antipsychotic regime, despite theoretical and preclinical considerations, has not been proved to enhance cognitive function, attenuate fatigue, enhance activity, improve negative symptoms and reduce weight in patients with schizophrenia.
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Liu YP, Tung CS, Chuang CH, Lo SM, Ku YC. Tail-pinch stress and REM sleep deprivation differentially affect sensorimotor gating function in modafinil-treated rats. Behav Brain Res 2010; 219:98-104. [PMID: 21167213 DOI: 10.1016/j.bbr.2010.12.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 12/04/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022]
Abstract
Prepulse inhibition (PPI) is a phenomenon in which a mild stimulus attenuates a cross-modality startle response to later intense stimulation. PPI is thought to index the central inhibitory mechanism through which behavioural responses are filtered. The present study compared the effects of two stress paradigms on the acoustic startle response (ASR) and on PPI in a rat model. The tail-pinch (TP) method produces an acute and immediate stressful condition, whereas rapid eye movement (REM) sleep deprivation (REMSD) leads to a more persistent and long-term stress. Our results demonstrated that in rats, TP stress reduced the size of the ASR, and REMSD impaired PPI. The wake-promoting agent modafinil (MOD) had no effect on PPI if given alone. However, MOD reduced the ASR and PPI under TP stress, whereas only PPI was reduced by MOD after 96 h of REMSD. These results suggest that distinct stress paradigms differentially mediated sensorimotor gating abilities in terms of either responsiveness to the stimulus or information-filtering capabilities.
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Affiliation(s)
- Yia-Ping Liu
- Department of Physiology and Biophysics, National Defence Medical Centre, Taipei, Taiwan, ROC.
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