[en] The present study reported that serum PRL, TSH and GH levels were all lowered obviously in thymectomized rats, while the above three hormone levels in serum increased in different degrees in the adrenalectomized male rats, and only serum PRL level increased in the testectomized rats. Forty eight hours after head irradiation with 10 Gy X-rays, these three hormone levels in serum all tended to reduce in the thymectomized and the adrenalectomized rats, but slightly increased in the testectomized rats. These results suggest that changes in the normal neuroendocrine regulatory function in three model rats probably prevented the effect of functional enhancement as seen after head irradiation in normal male rats

[en] The authors briefly reviewed the effects of ionizing radiation on central nervous system (CNS), including the effects of ionizing radiation on the developmental CNS, neurons, neural stem cells and gliocytes, the radio-responses of CNS injury and so on

[en] The present study showed that the functions of the hypothalamic-pituitary-gonadal and hypothalamic-adrenocortical systems changed in adult male rats thymectomized within 48 h after their birth. Two days later, head irradiation with 10 Gy x-rays was performed in the thymectomized male rats, serum LH and FSH, serum and urine testosterone and corticosterone, pituitary and testicular cAMP and hypothalamic β-EP and L-Enk contents were all reduced in different degrees, except the hypothalamic M-Enk content was increased, indicating that the changes were not in the same direction as those in intact male rats after head irradiation. These results suggest that the changes in head irradiated thymectomized male rats may differ from the changes seen in head irradiated intact male rats because of the influence of thymectomy on the neuroendocrine functions

[en] Objective: Effects of low dose radiation on signal transduction of neurons in mouse hypothalamus were investigated. Methods: In the present study competitive protein binding assay, radioimmunoassay, in situ hybridization and immunohistochemistry were used to observe the effects of whole-body irradiation with 75 mGy X-rays on the contents of cAMP and cGMP and the expressions of c-fos mRNA, Fos protein and proopiomelanocortin (POMC) mRNA in neurons of mouse hypothalamus. Results: The results showed that cAMP content in mouse hypothalamus immediately increased significantly and reached the peak value at 15 min after irradiation, and then returned to near the sham-irradiation level 1 h after irradiation; the changes of cGMP content were basically opposite to those of cAMP content, while the changes of cAMP/cGMP ratio were basically consistent with those of cAMP content.The expression of c-fos mRNA in the neurons of hypothalamus appeared 15 min after irradiation; The expression of Fos protein reached its peak value 8 h after irradiation. The expression of POMC mRNA decreased significantly 1 h after irradiation. Conclusion: These findings implicate that low dose radiation may potentiate the activity of the neurons in mouse hypothalamus, expedite their signal transduction, and down-regulate the functions of hypothalamus-pituitary-adrenocortical axis

[en] The change in hypothalamic dopamine (DA), serum gonadotrophins (LH, FSH), urine testosterone (TS), testicular cAMP, and pituitary and testis indices at different intervals after irradiation of head with 10 Gy X-rays in male rats were observed. The results showed that DA and gonadotrophins changed essentially in the same direction following head irradiation. The change in testicular cAMP content which coincided with that of serum gonadotrophins was especially interesting. The urine TS content changed in the same direction with that of serum LH. The pituitary and testicular indices showed no marked changes. The above data illustrated that an acute irradiation of head could cause marked changes leading to release of hypothalamic DA and anterior pituitary gonadotrophins. The changes in testicular cAMP may be secondary to those of the LH release, and TS production and secretion may be closely related to the change in testicular cAMP under the regulation of gonadotrophins

[en] Objective: In present study the authors observed the effect of whole body irradiation (WBI) with 75 mGy X-rays on the immune function of tumor-bearing mice. Methods: Lewis lung carcinoma cells were implanted into the right thigh muscle of C57BL/6J mice. Ten days after tumor implantation, the tumor-bearing mice were administrated with 75 mGy X-rays WBI, then the mice were sacrificed 18 h after irradiation to detect the immune parameters including the spontaneous proliferation of thymocytes, the proliferative response of splenocytes to ConA and LPS, the cytotoxic activities of specific cytotoxic lymphocytes (CTL) and natural killer cells (NK), as well as lymphokine activated killer cells (LAK) in spleen. The methods the authors used were ³H-TdR incorporation or release assay. Results: the immune parameters of exposed tumor-bearing mice were much higher than those of sham-irradiated tumor-bearing mice (P<0.01). Conclusion: These results suggested that low dose radiation (LDR) could enhance the immune function of tumor-bearing mice, which might be of practical significance in the prevention and therapy of cancer

[en] The exposure of mammalian cells to X rays results in the prolongation of the cell cycle, including the delay or the arrest in G₁, S and G₂ phase. The major function of G₁ arrest may be to eliminate the cells containing DNA damage and only occurs in the cells with wild type p53 function whereas G₂ arrest following ionizing radiation has been shown to be important in protecting the cells from death and occurs in all cells regardless of p53 status. So the study on G₂ phase arrest of the cell cycle induced by ionizing radiation has currently become a focus at radiobiological fields

[en] It has been demonstrated that neonatal administration of monosodium glutamine (MSG) results in clearly defined lesions of the hypothalamic arcuate nucleus. The present study showed that neuroendocrine function changed significantly in adulthood when baby rats were injected with MSG (4 mg/g BW, ip) 2 and 4 days after their birth. The serum LH, FSH, TSH and GH and serum and urine testosterone (TS) levels and pituitary cAMP content were lower in MSG treated rats than those of intact rats, but the serum PRL level increased significantly and the testicular cAMP content did not change. Forty eight hours after head irradiation with 10 Gy X-rays in the male rats treated with MSG, the serum LH, FSH, TSH and GH and serum and urine TS levels tended to decrease, while the serum PRL level tended to increase and the pituitary and testicular cAMP contents didn't change. The results suggest that the functional irregularity of neuroendocrine system in MSG treated rats with extensive lesions of hypothalamic arcuate nucleus were not so significant as those of intact rats in response to irradiation

[en] Objective: In present study the authors observed the adaptive response of thymocyte apoptosis induced by low dose radiation (LDR). Methods: In the experiment the model of Kunming male mice with whole-body irradiation (WBI) was used. The inductive dose (D₁) was 75 mGy and the challenge dose (D₂) was 1.5 or 2.0 Gy. The interval time between D₁ and D₂ was 6 h. Results: The percentages of thymocyte apoptotic bodies (TAB) in D₁ + D₂ group 18 h after WBI with D₂ were significantly lower than those in D₂ group (P<0.05). In addition, when the extracellular fluid of the splenocytes irradiated with 75 mGy was put into the thymocyte suspension irradiated with 2.0 Gy, the percentages of TAB after the incubation for 72 h were significantly lower than those in 2.0 Gy irradiated thymocytes (P<0.05). Conclusion: These results suggest that LDR (75 mGy) could change the external environment of immune cells, decrease the thymocyte apoptosis and induce and adaptive response of thymocyte apoptosis in the mice irradiated subsequently with larger dose (1.5 or 2.0 Gy) of X-rays

[en] In present study, the changes of hypothalamic endogenous opiate peptides and the endocrine function of pituitary and testes were observed at 1, 23, 63 and 97 days after exposure of testes to 10 Gy X-rays in male Wistar rats to attempt to clarify the neuroendocrine effect of ionizing radiation and its mechanism. One day after irradiation, hypothalamic β-endorphin (β-EP) content increased significantly, but serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (TS) and cAMP content in tests were lowered in varying degrees. Twenty three days after irradiation, hypothalamic β-EP content decreased, while serum LH, FSH, TS and testicular cAMP content increased very significantly. Sixty three days after irradiation, the level of hypothalamic β-EP still was the same as that at 23 days after irradiation, hypothalamic leu-enkephalin (L-Enk) content decreased significantly, serum LH and FSH levels still continued to increase up, while serum TS and testicular cAMP contents declined very significantly. Ninety seven days after irradiation, serum LH and FSH levels returned to lower, serum TS and testicular cAMP content still continued to decrease, and in testicular tissue, serious lesion occurred