(Hypertension. 2002;39:e15.)
© 2002 American Heart Association, Inc.
Letters to the Editor |
Neurobiology of Birth Weight Influence on Blood Pressure Values and Variability in Children and Adolescents
East Cleveland, Ohio
To the Editor:
Lurbe et al1 find an independent and significant inverse relationship for birth weight and 24-hour systolic blood pressure in 630 healthy children, ages 4 to 18 years (P<0.001). Likewise, birth weight was independently and inversely correlated with 24-hour systolic blood pressure variability (P<0.03).
Neurobiological features are suggested by a report that dopamine is a potent inhibitor of growth hormone and by studies linking anxiety and vasospasm with dopamine abnormalities lateralized to the right hemisphere. This hypothesis is supported by optimal response organization and working memory at intermediate dopamine tone in a mediofrontostriatal activation system, and deactivation of the right hemisphere, a state marker of depression, that promotes dominance of the left hemisphere associated with cardiac dysrhythmia and vasoconstriction.2,3
These findings should prompt clarification of the relationship of low birth weight to blood pressure1 by neurochemical and pharmacotherapeutic investigation of ancient neuromodulatory systems in complex evolving brains.3–5
References
1.
Lurbe E, Torro I, Rodriguez C, Alvarez V, Redon J. Birth weight influences blood pressure values and variability in children and adolescents. Hypertension. 2001; 38: 389–393.
2. Friedman EH. Neurobiology of short stature and prognosis of coronary heart disease in women. J Intern Med. 2000; 247: 517–518. (Letter)[Medline] [Order article via Infotrieve]
3. Friedman EH. Neurobiology of behavioral changes after prenatal exposure to paroxetine (Paxil). Am J Obstet Gynecol. 2000; 183: 518–519. (Letter)[Medline] [Order article via Infotrieve]
4.
Falkenburger BH, Barstow KL, Mintz IM. Dendrodendritic inhibition through reversal of dopamine transport. Science. 2001; 293: 2465–2470.
5.
Blakely RD. Dopamine’s reversal of fortune. Science. 2001; 293: 2407–2409.
Response
Department of Pediatrics, University of Valencia, Valencia, Spain
We appreciate the interest Dr Friedman has shown in our research on the impact of birth weight on the values and/or characteristics of blood pressure during childhood and adolescence, which was published in the September 20011 issue. An inverse relationship between birth weight and blood pressure levels has been demonstrated not only by our group,2 but also by others.3
The mechanistic link between birth weight and blood pressure (BP), however, remains elusive. Increased fetal exposure to maternal glucocorticoids, which exert organizational effects or imprinting patterns of response in vascular structures and cerebral tissue that persist throughout life, has been implicated.4 Glucocorticoids in maternal circulation are normally prevented from gaining access to the fetus by a placental enzyme, 11-ß-hydroxyesteroid dehydrogenase, which catalyzes the rapidly metabolized cortisol and corticosteroid into inactive products. Studies conducted in rats demonstrated a low activity level of this enzyme in newborn animals that have a large placenta but a low birth weight.5 Furthermore, the administration of low doses of dexamethasone to pregnant rats led to persistently raised blood pressure in their offspring.6 Whether or not an increase in glucocorticoids exposure may modify dopamine metabolism in intrauterine life has not been explored until now. Neurobiological research can be one of the ways to a better understanding of this complex process.
References
1.
Lurbe E, Torro I, Rodriguez C, Alvarez V, Redon J. Birth weight influences blood pressure values and variability in children and adolescents. Hypertension. 2001; 38: 389–393.
2. Lurbe E, Redon J, Alvarez V, Durazo R, Gomez A, Tacons J, Cooper RS. Relationship between birth weight and awake blood pressure in children and adolescents in absence of intrauterine growth retardation. Am J Hypertens. 1996; 9: 787–794.[CrossRef][Medline] [Order article via Infotrieve]
3. Huxley RR, Shiell AW, Law CM. The role of size at birth and postnatal catch-up growth in determining systolic blood pressure: a systematic review of the literature. J Hypertens. 2000; 18: 815–831.[CrossRef][Medline] [Order article via Infotrieve]
4. Edwards C, Benediktsson R, Lindsay R, Seckl J. Disfunction placental glucocorticoid barrier: link between fetal environment and adult hypertension. Lancet. 1993; 341: 355–357.[CrossRef][Medline] [Order article via Infotrieve]
5. Benediktsson R, Lindsay RS, Noble J. Glucocorticoid exposure in utero: new model for adult hypertension. Lancet. 1993; 341: 339–341.[CrossRef][Medline] [Order article via Infotrieve]
6. Tonolo G, Fraser R, Connel JMC. Chronic low-dose infusions of dexamethasone in rats: effect on blood pressure, body weight and plasma atrial natriuretic peptide. J Hypertens. 1988; 6: 25–31.[Medline] [Order article via Infotrieve]
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