Effects of Radiation on Blood Pressure and Body Weight in the Spontaneously Hypertensive Rat Model. Are Radiation Effects on Blood Pressure Affected by Genetic Background?

Can vildagliptin protect against radiation-induced premature ovarian failure? Insights into the AMPK and AKT signaling pathways

BACKGROUND

Among the detrimental side effects caused by radiotherapy in young females is the ovarian damage, eventually causing premature ovarian failure (POF). While many signaling pathways contribute to the pathogenesis of POF, to date no sufficient data exist on the AMPK and AKT signaling pathways in irradiated ovaries. Both AMPK and AKT play crucial roles in the process of folliculogenesis. Vildagliptin (vilda) is a dipeptidyl peptidase-4 inhibitor with modulatory effect on both AMPK and AKT. Therefore, our study aimed to investigate the biochemical changes that occur in the AMPK/AKT signaling pathway, and the effect of co-administration of vildagliptin in radiation-induced POF.

METHODS

Female Sprague-dawley rats were randomly divided into four groups: control, radiation, radiation + vilda, or vilda alone groups. Vilda was administered orally once/day, and on the 10th day of the experiment, radiation and radiation + vilda group rats were subjected to 3.2 Gy of whole-body gamma irradiation. Behavioral activity was assessed on the 13th day of the experiment. On day 14 of the experiment, all rats were euthanized. Serum samples were collected, and ovaries were dissected for histological and biochemical analyses.

RESULTS

Irradiation of female rats resulted in increased locomotor hyperactivity, impaired memory, and ovarian damage as evidenced by the marked histopathological deterioration. Additionally, irradiation led to a significant decrease in body weight gain, gonadosomatic index, and serum estradiol level. Further, it caused a significant increase in serum AMH, phosphorylated AMPK, phosphorylated AKT, cytoplasmic Nrf2 expression and phosphorylated CREB levels. Co-administration of vilda exhibited neuroprotective effects, preserved the ovarian histological architecture but failed to preserve the primordial follicle pool in irradiated rats.

CONCLUSION

In conclusion, AMPK/AKT signaling pathway is upregulated in radiation-induced POF. It possibly contributes to POF pathogenesis by accelerating the activation of primordial follicles, hence leading to their premature depletion. Coadministration of vilda can protect the ovaries and temporarily preserve its endocrine function; however, it does not sustain the ovarian reproductive capacity due to the early depletion of the pool of primordial follicles. Women undergoing radiotherapy should be cautious with the use of AKT-activating drugs.

The Radioprotective Effect of LBP on Neurogenesis and Cognition after Acute Radiation Exposure

BACKGROUND

Radiation exposure has been linked to the development of brain damage and cognitive impairment, but the protective effect and mechanism of Lycium barbarum pills (LBP) on radiation-induced neurological damage remains to be clarified.

METHODS

Behavioral tests and immunohistochemical studies were conducted to evaluate the protective effects of LBP extract (10 g/kg orally daily for 4 weeks) against radiation-induced damage on neurogenesis and cognitive function in Balb/c mice exposed to 5.5 Gy X-ray acute radiation.

RESULTS

The results showed that the LBP extract significantly improved body weight loss, locomotor activity and spatial learning and memory. Immunohistochemical tests revealed that the LBP extract prevented the loss of proliferating cells, newly generated neurons and interneurons, especially in the subgranular area of the dentate gyrus.

CONCLUSION

The findings suggest that LBP is a potential neuroprotective drug for mitigating radiation-induced neuropsychological disorders.

Nanoparticles for active combination radio mitigating agents of zinc coumarate and zinc caffeinate in a rat model

Zinc coumarate and zinc caffeinate nanoparticles (ZnCoNPs, ZnCaNPs) affect different biological processes. This study aimed to evaluate the mitigating action of ZnCoNPs in combination with ZnCaNPs against liver damage induced by gamma rays (γ-rays). Rats were exposed to 7 Gy of γ-rays and then injected intraperitoneally (i.p) with ZnCoNPs [2U/rat/day (5 mg/kg)] and ZnCaNPs [2U/rat/day (15 mg/kg)] for 7 consecutive days. The results showed that irradiated rats treated with ZnCoNPs (5 mg/kg/body weight) in combination with ZnCaNPs (15 mg/kg/body weight) for 7 days had a significant increases in body weight, antioxidant levels, T helper cell 4 (cluster of differentiation 4 (CD4)), and T cytotoxic cell 8 (cluster of differentiation 8 (CD8)), associated with a marked decrease in lipid peroxidation (LP), nitric oxide(NOx), total free radicals concentrate (TFRC), and DNA fragmentation. There were positive alterations in the morphological state, hematological parameters and the cell cycle phases. Additionally, the histopathological study demonstrated an improvement in the liver tissue of irradiated rats after treatment. Thus, ZnCoNPs and ZnCaNPs could be used as natural mitigating agents to reduce the hazards of ionizing radiation.

Irradiation of the kidneys causes pathologic remodeling in the nontargeted heart: A role for the immune system

Cardiac disease is a frequent and significant adverse event associated with radiotherapy for cancer. Identifying the underlying mechanism responsible for radiation injury to the heart will allow interventions to be developed. In the present study, we tested if local kidney irradiation results in remodeling of the shielded, nontargeted heart. One kidney, two kidneys, or the total body of male WAG and Dahl SS rats were irradiated with 10 Gy of X-rays. Local kidney irradiation resulted in systemic hypertension, increased BUN, infiltration of T lymphocytes, natural killer cells, and macrophages into the renal cortex and medulla, and renal fibrosis. Local irradiation of kidneys in WAG rats resulted in remodeling in the nontargeted heart after 120 days, manifested by perivascular fibrosis and increased interventricular septal thickness, but was not seen in Dahl SS rats due to a high baseline level of fibrosis in the sham-irradiated animals. Genetic depletion of T cells mitigated the nephropathy after local kidney irradiation, indicating a role for the immune system in mediating this outcome. Local kidney irradiation resulted in a cascade of pro-inflammatory cytokines and low-molecular weight metabolites into the circulation associated with transmission of signals resulting in pathologic remodeling in the nontargeted heart. A new model is proposed whereby radiation-induced cardiac remodeling in susceptible animals is indirect, with lower hemi body organs such as the kidney exporting factors into the circulation that cause remodeling outside of the irradiated field in the shielded, nontargeted heart. This nontargeted effect appears to be mediated, in part, by the immune system.

Association between low doses of ionizing radiation, administered acutely or chronically, and time to onset of stroke in a rat model

Exposure to high-doses of ionizing radiation has been reported to be associated with the risk of stroke. However, risks associated with lower dose exposures remain unclear, and there is little information available for the risk modification according to the dose-rate. There are few studies using animal models which might be able to provide complementary information on this association. In this study, the male stroke-prone spontaneously hypertensive rat (SHRSP) was used as a model animal. The rats were acutely irradiated with doses between 0 and 1.0 Gy or chronically irradiated with a cumulative dose of 0.5 or 1.0 Gy (at a dose rate of 0.05 or 0.1 Gy/day, respectively). The onset time of stroke related symptoms in SHRSP was used as an endpoint for evaluating the effects of low dose and the low dose-rate gamma-ray exposures. With respect to acute exposure, the time to the onset of stroke in the irradiated rats suggested the presence of a threshold around 0.1 Gy. For the low dose-rate chronically exposed, no significant increase in stroke symptom was observed. These findings are novel and demonstrate that the SHRSP system can be used to determine the association between the risk of stroke and radiation exposure with high sensitivity. Moreover, these studies provide important information regarding the association between the low dose and low dose-rate radiation exposure and circulatory diseases, especially stroke.