Periods of susceptibility

Evidence from epidemiological studies demonstrates that exposures during early life stages can impact susceptibility to diabetes and obesity later in life (Lau Rogers, 2005). In particular, numerous studies have linked poor maternal nutrition with later risk for these adverse health outcomes. The Dutch Hunger Winter was a 

1) Periods of susceptibility during pituitary gland development 

3) Consequences of alterations in growth hormone and glucocorticoid signalling 

4) Consequences of disruption of hypothalamic regulation of pituitary prolactin secretion 

Maternal prolactin via the milk is required for normal development of the tuberoinfundibular neuronal system of the hypothalamus during the neonatal period in rats (Shyr et al., 1986). Blocking the suckling-induced rise in maternal prolactin levels causes abnormal tuberoinfundibular function, with decreased inhibition by dopamine of prolactin secretion in the offspring later in life. The resulting chronically elevated prolactin levels cause prostatitis in the male offspring (Tangbanluekal Robinette, 1993). 

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As noted in chapter 3 on normal development, maturation of organ systems extends into the fetal and postnatal periods. Therefore, the notion of critical periods of susceptibility can be extended for... 

Adverse effects in children may result from exposure prior to conception (paternal and/or maternal), during prenatal development, or postnatally to the time of full maturity. Even within a given developmental stage, shorter intervals of exposure may determine susceptibility for particular outcomes. Different organ systems develop at different rates, but it has been shown that for each developmental stage, there are both broad windows of susceptibility and more specific periods of susceptibility (Faustman et al., 2000 ... 

Period of susceptibility for exposure Neurological Reproductive Renal Endocrine... 

Examples of chemicals that cause birth defects in various organ systems are discussed in subsequent sections, along with periods of susceptibility of chemicals for these organ systems and for cancer. 

Bennett GD Finnell GD (1998) Periods of susceptibility to induced malformations of the developing mammalian brain. In Slikker WJ Chang LW eds. Handbook of developmental neurotoxicology. San Diego, CA, Academic Press, pp 189-208. 

The period of susceptibility in humans occurs primarily in the first 60 days of pregnancy, at a time when a woman might not be aware of her pregnancy. 

To fully understand the critical periods of susceptibility for toxicity to the primate immune system, an understanding of the timings of the development of each of the major immune system organs is required. The following narrative briefly describes the development of the macaque immune system and discusses the relevance of these timings to developmental toxicity study designs. 

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