The effect of long-term nicotine exposure on bone mineral density and oxidative stress in female Swiss Albino rats

The Effects of Nicotine- and Cigarette-Related Products on Osteogenesis, Bone Formation, and Bone Mineralization: A Systematic Review

BACKGROUND

Many clinicians associate nicotine as the causative agent in the negative and deleterious effects of smoking on bone growth and spine fusion. Although nicotine is the primary driver of physiological addiction in smoking, isolated and controlled use of nicotine is one of the most effective adjuncts to quitting smoking.

OBJECTIVE

To explore the relationship between nicotine and noncombustion cigarette products on bone growth.

METHODS

One thousand five studies were identified, of which 501 studies were excluded, leaving 504 studies available for review. Of note, 52 studies were deemed to be irrelevant. Four hundred fifty-two studies remained for eligibility assessment. Of the remaining 452, 218 failed to assess study outcomes, 169 failed to assess bone biology, 13 assessed 5 patients or fewer, and 12 were deemed to be ineligible of the study criteria. Forty studies remained for inclusion within this systematic review.

RESULTS

Of the 40 studies identified for inclusion within the study, 30 studies were classified as "Animal Basic Science," whereas the remaining 10 were categorized as "Human Basic Science." Of the 40 studies, 11 noted decreased cell proliferation and boney growth, whereas 8 showed an increase. Four studies noted an increase in gene expression products, whereas 11 noted a significant decrease.

CONCLUSION

The results of this study demonstrate that nicotine has a variety of complex interactions on osteoblast and osteoclastic activities. Nicotine demonstrates dose-dependent effects on osteoblast proliferation, boney growth, and gene expression. Further study is warranted to extrapolate the effects of solitary nicotine on clinical outcomes.

Bone status of acetylcholinesterase-knockout mice

Acetylcholinesterase (AChE) hydrolyzes acetylcholine (ACh) to acetate and choline and thereby terminates nerve impulse transmission. ACh is also expressed in bone tissue and enhances here proliferation and differentiation of osteoblasts, which makes it interesting to investigate effects of AChE deficiency on bone. To our knowledge, this is the first study that analyzed bone of heterozygous acetylcholinesterase-knockout (AChE-KO) mice. Tibia, femur, thoracic and lumbar vertebrae of 16-week-old female heterozygous AChE-KO mice and their corresponding wildtypes (WT) were analyzed using real-time RT-PCR, dual-energy X-ray absorptiometry, biomechanics, micro-computed tomography, histology and histomorphometry. Our data revealed that heterozygous AChE-KO did not cause negative effects upon bone parameters analyzed. In contrast, the number of osteoclasts per perimeter was significantly reduced in lumbar vertebrae. In addition, we found a significant decrease in trabecular perimeter of lumbar vertebrae and cortical area fraction (Ct.Ar/Tt.Ar) in the mid-diaphysis of femurs of AChE-KO mice compared to their WT. Therefore, presumably a local homozygous knockout of AChE or AChE-inhibitor administration might be beneficial for bone formation due to ACh accumulation. However, many other bone parameters analyzed did not differ statistically significantly between AChE-KO and WT mice. That might be reasoned by the compensating effect of butyrylcholinesterase (BChE).

The biological effects of tocotrienol on bone: a review on evidence from rodent models

Osteoporosis causes significant health care and economic burden to society, leading to a relentless search for effective preventive agents. Tocotrienol, a member of the vitamin E family, has demonstrated promising potential as an osteoporosis-preventing agent. This review summarizes evidence on the effects of tocotrienol on bone in animal models. Techniques used to examine the effects of tocotrienol on bone in animals included bone histomorphometry, X-ray microtomography, dual-energy X-ray absorptiometry, bone turnover markers, bone calcium content, and biomechanical strength. Tocotrienol was shown to improve osteoblast number, bone formation, mineral deposition, and bone microarchitecture in osteopenic rats. It also decreased osteoclast number and bone erosion in the rats. Tocotrienol supplementation resulted in an improvement in bone mineral density, although biomechanical strength was not significantly altered in the rats. The beneficial effects of tocotrienol on bone can be attributed to its role as an antioxidant, anti-inflammatory agent, suppressor of the mevalonate pathway, and modulator of genes favorable to bone formation.

Infertility and the presence of insulin resistance are associated with increased oxidative stress in young, non-obese Turkish women with polycystic ovary syndrome

STUDY OBJECTIVE

To investigate the relationship between both insulin resistance and fertility and the oxidant/antioxidant system in young, non-obese patients diagnosed with polycystic ovary syndrome (PCOS).

DESIGN

Case-control study.

SETTING

Department of Obstetrics and Gynecology, Ege University, Izmir, Turkey.

PARTICIPANTS

PCOS patients without insulin resistance (IR-) (n = 33), PCOS patients with insulin resistance (IR+) (n = 27), and healthy controls (n = 30). Patients with PCOS and regular sexual intercourse were further divided into infertile (n = 14) and fertile (n = 15) groups.

MAIN OUTCOME MEASURES

The malondialdehyde (MDA) and thiol levels as well as the catalase (CAT) and superoxide dismutase (SOD) enzyme activities.

RESULTS

Both IR+ and IR- PCOS patients had higher MDA levels and lower thiol levels when compared to the controls (each P < .001). However, only IR- patients had significantly higher SOD (3700.81 ± 410.13 vs 2614.19 ± 611.80 U/g Hb; P < .001) and CAT (7565.06 ± 628.27 vs 6819.61 ± 539.2 U/g Hb; P < .001) activities when compared to the controls. Infertile PCOS patients had significantly higher MDA levels (347.5 ± 22.8 vs 278.6 ± 42.6 nmol/g Hb, P < .001) and lower thiol levels (498.5 ± 56.2 vs 568.5 ± 38.6 μmol/l, P = .001) when compared to fertile patients.

CONCLUSIONS

The results of this study demonstrated an imbalance in the oxidative-antioxidative system of PCOS patients. This imbalance was worse in IR+ and infertile PCOS patients.

Effects of 1,8-cineole on hypertension induced by chronic exposure to nicotine in rats

Objectives

The monoterpenic oxide 1,8-cineole is a major component of many essential oils. We investigated its effects on systolic blood pressure (SBP) and oxidative stress in rats chronically exposed to nicotine.

Methods

Male Sprague–Dawley rats (100–120 g) were intraperitoneally injected with 0.8 mg/kg/day nicotine for 21 days, followed by 3 mg/kg nicotine the next day. Rats were subsequently injected intraperitoneally with 0.01, 0.1 and 1 mg/kg 1,8-cineole, or 10 mg/kg nifedipine. SBP was measured using a tail cuff transducer, plasma nitrite concentration was measured colorimetrically, and plasma corticosterone concentration was measured by enzyme immunoassay.

Key findings

We found that 0.1 mg/kg 1,8-cineole significantly reduced SBP, and that 1.0 mg/kg 1,8-cineole significantly increased plasma nitrite concentrations, compared with rats chronically exposed to nicotine alone. Rats chronically exposed to nicotine showed a significant increase in lipid peroxidation levels, an elevation significantly antagonized by treatment with 0.01 mg/kg and 0.1 mg/kg 1,8-cineole. Chronic exposure to nicotine also significantly increased plasma corticosterone levels, but this effect was not diminished by treatment with 1,8-cineole.

Conclusions

These results indicate that 1,8-cineole may lower blood pressure, and that this antihypertensive effect may be associated with the regulation of nitric oxide and oxidative stress in rats chronically exposed to nicotine.