Estrogen-induced gonadotropin surge in rhesus monkeys is not inhibited by cortisol synthesis inhibition or hypoglycemia

Acute administration of corticotrophin-releasing hormone (CRH) has been shown to inhibit gonadotropin secretion in several species including rodents, sheep, humans, and nonhuman primates. Similarly, a variety of acute stressors have been shown to inhibit tonic gonadotropin secretion and may do so through a CRH mechanism. Stress-induced inhibition of tonic gonadotropin secretion below levels required for follicular maturation would be expected to inhibit ovulation. An additional mechanism whereby acute stressors could interfere with ovulation is through inhibition of the preovulatory gonadotropin surge. In the present study, we determined the effect of acute activation of the hypothalamic-pituitary-adrenal (HPA) axis on phasic gonadotropin secretion in female rhesus monkeys. Activation of the HPA axis was achieved by either a hypoglycemic challenge or blockage of cortisol synthesis with metyrapone, 24h after an estradiol benzoate challenge. Neither metyrapone nor insulin-induced hypoglycemia inhibited gonadotropin secretion. In fact, the initiation of the luteinizing hormone and folliclestimulating hormone surge was advanced by 7.4±0.4 h (p<0.001) and 4.8±1.4 h (p=0.04) respectively, in metyrapone-treated monkeys compared with saline controls. By contrast, hypoglycemia did not affect the gonadotropin surge. The gonadotropin surge was preceded by increased progesterone secretion in metyraponetreated but not insulin-treated monkeys. This difference in progesterone secretion likely explains the advancement of the gonadotropin surge in the metyraponetreated animals.     

新生儿糖代谢紊乱的临床研究

目的分析新生儿糖代谢紊乱的相关因素,探讨其预防和治疗措施。方法住院新生儿1783例进行血糖监测。所有息儿监测至2次空腹血糖正常为止。计数资料采用X2检验。结果发生糖代谢紊乱295例,其中低血糖症176例,高血糖症52例,二者兼有67例。血糖异常与胎龄呈显著负相关(P=0.001);与出生体质量呈显著负相关(P<0.01);小于胎龄儿(SGA)易发生糖代谢紊乱;轻度窒息组血糖紊乱以低血糖症为主,重度窒息组血糖紊乱以高血糖症居多(P<0.01);血糖恢复时间与窒息程度呈显著正相关(P<0.01);血糖异常与感染程度星显著正相关(P=0.019);糖尿病母亲婴儿易患低血糖症。结论对高危儿应尽早进行血糖监测,对血糖异常者及时处理,以减少或避免后遗症发生。     

Cerebral energy metabolism in insulin induced hypoglycemia in newborn piglets: in vivo31P-nuclear magnetic resonance spectroscopy

The effect of insulin induced hypoglycemia on cerebral energy metabolism was examined in four newborn piglets. Cerebral energy metabolism was assessed using in vivo ³¹P-nuclear magnetic resonance spectroscopy. It was demonstrated that the normal level of phosphocreatine/inorganic phosphate (PCr/Pi), an indicator of phosphorylation potential, was maintained at a blood glucose level of 40 mg/dL or above, whereas when blood glucose was reduced to less than 40 mg/dL, PCr/Pi rapidly decreased in parallel with this. Below the critical blood glucose level of 40 mg/dL, a positive correlation (y = 0.02x + 0.632; r = 0.668; P < 0.001) existed between blood glucose and PCr/Pi. In the present investigation, a reduction of blood glucose level to 20 mg/dL or lower resulted in a PCr/Pi of less than 1, indicating a state of cerebral energy failure. The intracellular pH (pHi) was 7.08 ± 0.05 at the onset and 7.15 ± 0.07 in the hypoglycemic state, indicating no significant difference between the two groups. The present study has clarified that cerebral energy failure occurs when the blood glucose level is about 20 mg/dL or lower. The critical point of blood glucose exists to maintain brain energy metabolism.     

Follow-up of Children of Insulin-dependent and Gestational Diabetic Mothers: Neuropsychological Outcome

ABSTRACT. Ninety-four infants of 28 weeks gestation or more were born to 85 women, 64 type I and 21 gestational diabetics, between 1969–1972 at Sabbatsberg's Hospital, Stockholm. Perinatal mortality rate was 6.3%. The follow-up study was conducted when the children were approximately 5 years of age and included a physical and a neurological evaluation, IQ determination of mother and child, and an interview of mother by a psychologist. Fifty-three infants of insulin-dependent (IDM) and 20 infants of gestational diabetic mothers (IGDM) (83 %) participated, 3 families could not be traced and 12 were unwilling. The group lost to follow-up (13 IDM, 2 IGDM) had more perinatal complications induding congential malformations than the follow-up group. All children had normal physical and neurological development. IQ was normal, the majority were above 100, the average in IDM was 115 (range 89–144) and 112 in IGDM (range 95–133). No obvious relationship was found between maternal acetonuria during pregnancy, infant birthweight, blood glucose during first hours after birth or neonatal complications and IQ of the children. A correlation (r= 0.364, p<0.01) was found between maternal and child IQ. Mothers exhibiting emotional disorders (anxiety, depression) had significantly higher life stress scores based on 29 stress variables and reported more frequently about conduct and behavioural disorders in their children than mothers without emotional disturbances.     

Effects of severe hypoglycemia on the human brain neuropathological case reports

The neuropathological findings in two cases of irreversible hypoglycemic brain injury are described. A 26-year-old diabetic man injected insulin without adequate food intake and died after 2 months in coma. An 84-year-old nondiabetic man accidentally received 10 mg of glibenclamide and died after 3 months in relatively superficial coma.
In the first case, an extensive necrotizing injury with gliosis was present in the cerebral cortex with temporal preponderance, as well as in the amygdalae and hippocampus. Lesions were also present in the putamen and caudate nucleus whereas the globus pallidus and thalamus were less severely destroyed. The distribution of the lesions was therefore somewhat different from that commonly seen in hypoxic-ischemic brain injury, which, together with some previously published data, suggests some difference in the pathogenesis of hypoglycemic vs. hypoxic-ischemic brain injury.
In the second case only a slight loss of cortical neurons with secondary gliosis could be attributed to the hypoglycemic insult. This case demonstrates the danger of accidental intake of sulfonylurea preparations, which can cause an irreversible brain injury due to their prolonged hypoglycemic effect.     

The cerebral redox state in cats during severe insulin induced hypoglycemia

The cerebral metabolic state was studied in cats during insulin-induced hypoglycemia and the recovery after glucose infusion. Changes in the redox state of nicotinamide adenine dinucleotide (NAD) were monitored from the surface of the exposed cerebral cortex using microfluorometry. After insulin injection blood glucose fell from 6.85 μmol/ml to 0.45 μmol/ml at EEG isoelectricity and was accompanied by an oxidation of NADH⁺. Upon intravenous glucose infusion EEG activity rapidly returned and NAD became more reduced. The oxidation of NADH⁺ during severe hypoglycemia demonstrated that the in vivo redox state of mitochondria behave in a similar manner as isolated mitochondria when reducing equivalents become limiting to the respiratory chain.     

Megestrol acetate promotes euglycemia and appetite in a child with persistent hyperinsulinemic hypoglycemia of infancy

This report describes a successful treatment with megestrol acetate in a child with persistent hyperinsulinemic hypoglycemia of infancy (PHHI). An 8-y-old child with PHHI treated with octreotide had marked impairment of appetite sensation and feeding skills. Within 3 wk of starting megestrol acetate (8 mg/kg/d) to stimulate her appetite, she had a significant improvement. By 1 y postinitiation, she had acquired age-appropriate eating habits. The megestrol acetate caused hyperglycemia, necessitating the discontinuation of all other therapy for her hypoglycemia. Her height growth remained normal but she was found to have asymptomatic adrenal suppression. CONCLUSION: Megestrol acetate appeared to stimulate appetite and regulate glucose homeostasis in this child with PHHI. Additional studies will be required to document its efficacy and safety in other children with this disorder.     

A case of severe diazoxide toxicity

Hyperinsulism is a rare cause of persistent hypoglycemia in the neonatal period. Therapy can be accomplished either surgically or pharmacologically. Diazoxide treatment remains the mainstay of medical therapy. Tolerance of diazoxide is usually excellent, but several adverse effects of this drug have been described. A case of severe diazoxide intoxication with fluid retention, congestive heart failure, and respiratory failure is reported. The patient was a 43-day-old infant, affected by persistent and severe hypoglycemia. After the diagnosis, hyperinsulinism was established he was treated with diazoxide (17 mg x kg(-1) daily) and octreotide (12 microg x kg(-1) daily). A few days later he presented with hepatomegaly, severe fluid retention, diffuse edema, congestive heart failure, and respiratory failure requiring mechanical ventilation. After introduction of ACE inhibitors he developed acute renal failure. The clinical condition worsened and he developed pulmonary hypertension requiring high-frequency oscillatory ventilation. Diazoxide was stopped on the 12th day in spite of poor control of blood sugar. During the next 5 days his hemodynamic status dramatically improved and he was weaned from catecholamines: he lost weight, had a negative fluid balance, and the edema disappeared, a normal diuresis resumed and renal function improved. Improvement of respiratory patterns and gas exchange made it possible to switch back to conventional ventilation and then to extubate the patient. Echocardiography demonstrated reduction of the PA pressure to normal and resolution of atrial enlargement. The patient was scheduled for elective subtotal pancreatectomy. Diagnosis and management of diazoxide intoxication are discussed.     

The Insulin Hypoglycemia Test: Hypoglycemic Criteria and Reproducibility

The insulin hypoglycemia test (IHT) is widely regarded as the "gold standard" for dynamic stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. This study aimed to investigate the temporal relationship between a rapid decrease in plasma glucose and the corresponding rise in plasma adenocorticotropic hormone (ACTH), and to assess the reproducibility of hormone responses to hypoglycemia in normal humans. Ten normal subjects underwent IHTs, using an insulin dose of 0.15 U/kg. Of these, eight had a second IHT (IHT2) and three went on to a third test (IHT3). Plasma ACTH and cortisol were measured at 15-min intervals and, additionally, in four IHT2s and the three IHT3s, ACTH was measured at 2.5- or 5-min intervals. Mean glucose nadirs and mean ACTH and cortisol responses were not significantly different between IHT1, IHT2 and IHT3. Combined data from all 21 tests showed the magnitude of the cortisol responses, but not the ACTH responses, correlated significantly with the depth and duration of hypoglycemia. All subjects achieved glucose concentrations of of < or = 1.6 mmol/l before any detectable rise in ACTH occurred. In the seven tests performed with frequent sampling, an ACTH rise never preceded the glucose nadir, but occurred at the nadir, or up to 15 min after. On repeat testing, peak ACTH levels varied markedly within individuals, whereas peak cortisol levels were more reproducible (mean coefficient of variation 7%). In conclusion, hypoglycemia of < or = 1.6 mmol/l was sufficient to cause stimulation of the HPA axis in all 21 IHTs conducted in normal subjects. Nonetheless, our data cannot reveal whether higher glucose nadirs would stimulate increased HPA axis activity in all subjects. Overall, the cortisol response to hypoglycemia is more reproducible than the ACTH response but, in an individual subject, the difference in peak cortisol between two IHTs may exceed 100 nmol/l.