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| ORIGINAL ARTICLE |
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| Year : 2021 | Volume
: 9
| Issue : 2 | Page : 68-73 |
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Effect of night shiftwork on lipid profile, hematological, and immunoinflammatory parameters in adult male wistar rats
Mahdi Gambo Dissi1, Salisu Ahmed Ibrahim1, Yusuf Tanko2, Aliyu Mohammed2
1 Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano, Nigeria
2 Department of Human Physiology, Faculty of Basic Medical Sciences, College of Medical Sciences, Ahmadu Bello University, Zaria, Kaduna, Nigeria
| Date of Submission | 23-Nov-2020 |
| Date of Decision | 10-Jan-2021 |
| Date of Acceptance | 11-Jan-2021 |
| Date of Web Publication | 10-Aug-2021 |
Correspondence Address:
Dr. Mahdi Gambo Dissi
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/njecp.njecp_47_20
Background: Adverse health outcomes of night shiftwork (NSW) have been reported from observational studies but interventional researches mimicking NSW are dearth. This study aimed to simulate NSW and investigate its effect on lipid profile, hematological, and immunoinflammatory parameters in adult male Wistar rats. Materials and Methods: Sixteen male Wistar rats aged between 8 and 10 weeks, weighing 100 g ± 12 g were equally and randomly divided into control and NSW groups. Night shift-work group was sleep restricted and exposed to light at night for 6 weeks. Lipids were analyzed using their respective Randox kits and chemistry Autoanalyser (mindry Ba-88a). Full blood count was done using an Automated Hematology analyzer (Mindray BC-10) and CD 4+ T-cells were estimated using an automated Partec Cyflow counter. Data were analyzed using SPSS V20.0 and summarized using mean ± standard error of means. Student's t-test was used to investigate differences between the groups and P ≤ 0.05 was considered as statistically significant. Results: The results demonstrated NSW rats to exhibit trends toward lower high-density lipoprotein, higher triglycerides, low-density lipoprotein, and lipid ratios compared to controls (P > 0.05). In addition, NSW group exhibited significant reduction in total WBC count, marginal decrease in CD4+ T-cells, and absolute lymphopenia. In addition, while erythrothrombotic parameters of the two groups appeared statistically similar, platelets-to-lymphocytes ratio is slightly higher and red cell distribution width coefficient is significantly lower in the NSW group. Conclusion: The present study has demonstrated the potentials of night shiftwork to increase atherogenic lipids, lower cardioprotective lipids, impair immunological competence and increase systemic inflammation in male Wistar rats. These finding have highlighted the need for extensive research effort in order to fully understand mechanisms through which NSW affect immunoinflammation, metabolic and cardiovascular health.
Keywords: CD4+ tells, full blood count, lipid profile, lipid ratios, night shiftwork
How to cite this article:
Dissi MG, Ibrahim SA, Tanko Y, Mohammed A. Effect of night shiftwork on lipid profile, hematological, and immunoinflammatory parameters in adult male wistar rats. Niger J Exp Clin Biosci 2021;9:68-73 |
How to cite this URL:
Dissi MG, Ibrahim SA, Tanko Y, Mohammed A. Effect of night shiftwork on lipid profile, hematological, and immunoinflammatory parameters in adult male wistar rats. Niger J Exp Clin Biosci [serial online] 2021 [cited 2023 Mar 26];9:68-73. Available from: https://www.njecbonline.org/text.asp?2021/9/2/68/323671 |
| Introduction | |  |
The advent of electricity has made it possible for humans to shift their way of life away from the natural 12 h of light and 12 h of darkness towards a 24-h constant light society.[1] These civic and social opportunities coupled with societal, economic, and work demands has pushed for a round-the-clock demand and availability for health care, security, transport, and other services.[2],[3] Consequently, this has made shift and/or night work common in developed and even in the developing societies, hence accounting for 75% of the former's workforce.[3],[4]
Shiftwork, particularly night shifts, involves working irregularly mostly during the nigh/resting hours, thus requiring exposure to light at night (LAN), disruption of sleep and other physiological rhythms. In the long term, this physiological decoupling may cause coronary heart disease,[2] ischemic stroke[5] and cognitive impairments.[6] In addition, shiftwork involving circadian disruption has, since 2007, been categorized as group 2A carcinogen by the International Agency for Research on Cancer;[3] hence, could be regarded as an evolving pandemic requiring urgent research interests and public health attention.
To that regards, attempts have been made to investigate the functional perturbations associated with night shiftwork (NSW)[2],[5],[6] and LAN exposure.[1],[4],[7] However, most of these efforts on NSW have been limited to observational studies,[2],[5],[6] whereas, the interventional LAN exposure studies have failed to consider the contributing effects of sleep restriction (SR) encountered during NSW.[1],[4],[7]
Since shift/night work involves exposure to LAN[2],[6] and SR,[3],[6] designing an animal model, with concomitant LAN exposure and SR protocols, to simulate NSW and to investigate its effect on lipid profile, hematological, and immunoinflammatory parameters is timely.
| Materials and Methods | | |
Experimental animals, animal groupings and research protocol
A total of 16 male Wistar rats aged between 8 and 10 weeks, weighing 100 g ± 12 g were purchased from the animal house of the Department of Human Physiology, Bayero University, Kano, and were housed in metallic cages measuring 38 cm × 46 cm × 24 cm with saw dust beddings and average room temperature of 22°C–25°C. The animals were randomly divided into control (n = 8) and nightshift work (n = 8) groups and were allowed an acclimation period of 2 weeks during which they were maintained under the prevailing natural light: dark (12 L: 12D) conditions. For 6 weeks of the intervention period, feeds and tap water were made accessible throughout the dark portion of the day. NSW was simulated by SR and exposure to LAN during the first 5 h of photophase and scotophase, respectively.[8] SR was employed using gentle handling protocol while LAN exposure was done using ≈ 750 lx of white light, all, as previously described.[8] The research protocol was reviewed and approved by the Animal Use and Care Committee of Ahmadu Bello University, Zaria, Nigeria (ABUCAUC/2020/64).
Animal sacrifice and samples collection
At the end of the 6 weeks' intervention period, the two groups were allowed to resume their acclimation protocols for 24 h after which the rats were anaesthetized using an intraperitoneal injection of a cocktail of diazepam (2 mg/kg) and ketamine (20 mg/kg). Blood samples were then taken via cardiac puncture and were put into two separate containers; one, containing ethylene diamine tetra-acetic acid (EDTA) and the other, a plain container without EDTA. The blood samples containing EDTA were used to determine full blood counts (FBC) and CD4+ T cells, while blood samples in the plain containers were allowed to stand at room temperature for 30 min before being centrifuged at 2000G for 15 min at room temperature using a bench top centrifuge. Using a Pasteur's pipette, the serum layers were then aspirated and transferred into smaller, sterile, labeled, blank tubes, and stored in a refrigerator at 0°C for subsequent analysis of lipid profile.
Biochemical analysis
The analysis of samples was done at the laboratory units of Haematology Department, Aminu Kano Teaching Hospital and Human Physiology Department of Yusuf Maitama Sule University, Kano.
Total cholesterol (T. Chol.), serum triglyceride (Trigs), and serum high-density lipoprotein (HDL) were quantified using commercial kits and their respective protocols.[9],[10],[11] Serum low density lipoprotein (LDL) and very LDL (VLDL) were computed as LDL = TC-(HDL + Trigs/5) and VLDL = Trigs/5,[12] whereas total lipids were calculated as the sum total of all the components of the lipid profile.
Cardiac risk ratio and atherogenic index of plasma were calculated as TC/HDL and log (TG/HDL), respectively,[13] while atherogenic coefficient and Castelli's Risk Index-II were respectively determined as (TC-HDL)/HDL and LDL/HDL.[13],[14]
FBC was done using an Automated Hematology analyzer (Mindray BC-10) and CD4+ T-cells were estimated by impedance-based flow cytometry using an automated Cyflow counter 1 (Partec, Germany, 2017). Monocyte-high density lipoprotein ratio, monocyte-lymphocyte ratio (MLR) and platelet-lymphocyte ratio (PLR) were obtained by dividing monocyte with HDL and lymphocyte as well as dividing platelets by lymphocytes respectively.
Statistical analysis
Data were analyzed using the Statistical Package for Social Sciences (IBM SPSS) version 20.0 (IBM, Armonk, New York, USA). Student's t-test was used to investigate difference between groups and data were summarized as mean ± standard error of means. In all cases, P ≤ 0.05 was considered as statistically significant.
| Results | | |
From the results, it could be observed that, although lipid parameters and ratios appear statistically similar, NSW group exhibited a trend toward lower HDL, higher triglycerides, LDL, and all the calculated lipid ratios compared to controls [Table 1]. This is demonstrative that SR with concomitant exposure to LAN as obtained during NSW could increase atherogenic and lower cardioprotective lipids, hence could increase the risk of developing adverse cardiovascular conditions. | Table 1: Lipids profile and atherogenic lipid ratios among the various groups
Click here to view |
As shown in [Table 2], it could be observed that total WBC count of the NSW group is significantly lower than in controls [Table 2]. This is seen to be associated with significant absolute lymphopenia and marginal decrease in CD4+ T-cells count [Table 2]. In addition, although MLR is essentially similar between the groups, PLR is noted to be slightly higher in the NSW group compared to controls [Table 2]. These observations are demonstrative that NSW could be associated with a state of impaired immunological competence as well as increased inflammatory status.
On the other hand, the erythrothrombotic picture of the two groups is observed to be statistically similar except for a significantly lower RDWC [Table 3]. This could however be noted to be associated with a slight increase in MCV and red cell distribution width standard deviation (RDWS). Interestingly, it could also be observed that platelet large cell ratio (PLCR) is mildly increased among the NSW models [Table 3], re-iterating the increased inflammatory status observed earlier in [Table 2].
| Discussion | | |
Our general findings have demonstrated an overall state of increased atherogenic and lower cardioprotective lipid trend, impaired immunological competence as well as increased inflammatory status, pointing possible predisposition to infectious and inflammatory diseases as well as increased risk for adverse cardiovascular events.
Atherogenic indices and ratios are known to be important metabolic and cardiovascular disease risk indicators with higher values linked to increased risk of adverse metabolic and cardiovascular conditions.[14],[15] Interestingly, dyslipidemia and aberrant lipid metabolism have been associated with SR[16],[17] and LAN exposure[1] suggesting that night shift workers exposed to LAN and SR could come down with dyslipidemia and exhibit an increased risk of developing cardiometabolic disorder.[1],[5]
Our observed dyslipidemia trend among the NSW model rats could have been due to the tendency of SR to impair lipoprotein-a metabolism[17] and the ability of LAN to induce increased digestion and absorption of lipids as well as the enhancement of lipogenesis and decreased fecal cholesterol excretion.[4] Our finding of nonstatistically significant dyslipidemia, contrast the findings of statistically low HDL[18],[19] high triglycerides,[18] VLDL,[20] LDL, and total cholesterol levels[16],[17],[20] reported following SR,[16],[17],[18],[19] and LAN exposure.[20] On the other hand, no statistical difference in plasma triglycerides and LDL between LAN exposed and unexposed rats were observed following 5 weeks of intervention;[7] also, a recent systematic review and meta-analysis of 13 articles involving 83,037 participants had reported no statistical association between short sleep duration and higher triglycerides, LDL or low HDL levels.[21]
Nonetheless, a 6 weeks' study protocol has observed a trend similar to our findings in male Sprague–Dawley rats.[22] In addition, a 10 weeks long night shift work protocol found serum total cholesterol to be elevated, while serum triglycerides to be unaffected.[4] These finding and ours, corroborates human observational studies that LAN exposure and night shift work are strongly associated with lower HDL, elevated plasma triglycerides, and LDL.[23] Therefore, although we only demonstrated a dyslipidemia trend, the possibility of a causal relationship between NSW, dyslipidemia, and adverse cardiometabolic health cannot be discarded.
Melatonin is reported to have an anti-inflammatory potentials,[24] therefore, its suppression by LAN[3],[4],[6] could induce systemic inflammation. Similarly, as SR is known to cause systematic inflammation,[25] our NSW protocols could therefore result to increased systemic inflammatory status. In addition, while sleep serves to renew functions and processes related to immunological response[26] and ensures that circulating immune cells are in the right place at the right time,[27] light: dark cycle variation in migratory and bactericidal properties of immune cells have been observed.[28] Consequently, extended light exposure and SR encountered during NSW could increase systemic inflammation and compromise immune-cells production, diversity, migration, and response. Therefore, the finding of the present study that NSW rats exhibited a state of impaired immunological competence and a tendency for increased systemic inflammation agrees with this notion. In consonance with our findings, LAN have been reported to cause immunosuppression,[29] impair delayed-type hypersensitivity reaction,[29] and inhibit cellular and humoral immune functions.[30] In addition, immunosuppression,[31] decreased levels of CD4+ T cells, and phagocytic activity in neutrophils have been observed following sleep-restriction.[32] Similar to our finding, higher inflammatory status have been found following nightshift,[6] LAN exposure,[33] and SR.[25] In addition, our finding have corroborated the adverse immunological outcomes of shift work[34] and the increased likelihood of developing colds,[35] pneumonia,[36] and poor viral specific immune response and post vaccination antibody production[37] observed following SR protocols.
Sleep regulates hematopoiesis,[38] while melatonin plays a modulatory role in erythropoiesis and thrombopoiesis.[39] Therefore, SR and LAN exposure, as encountered during NSW, could disrupt the hematopoietic processes and lead to abnormal counts and/or morphology. Our present finding that erythrothrombotic blood picture of the two groups is statistically similar demonstrate that our NSW protocols did not significantly alter the hematopoietic physiology of the rats. This finding contrast the significantly higher nucleated erythrocytes and lower platelet counts observed in women working either half- or whole-night shifts.[6] On the other hand, the finding of the present study is in agreement with the findings of Visniauskas and colleagues,[40] as well as that of Nakao and others,[41] who respectively observed no difference in erythrocytes, platelets counts,[40] or platelet aggregation,[41] following sleep deprivation. Furthermore, our finding of significantly lower RDWC was noted to be associated with a slight increase in MCV and RDWS; in addition, it was observed that PLCR is mildly increased among the NSW models. This substantiates that the observed change in RDWC is unrelated to erythrocyte's size variability or inflammatory status.
Although we anticipated NSW to disrupt the hematopoietic regulatory role of sleep and the modulatory role of melatonin on thrombopoiesis and erythropoiesis, our finding have highlighted the need for an extensive research effort to fully understand the mechanisms through which NSW could affect the hematopoietic system.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]
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