Age- and sex-related differences in the nerve growth factor distribution in the rat brain

Tests Used to Assess the Cognitive Abilities of Aged Rats: Their Relation to Each Other and to Hippocampal Morphology and Neurotrophin Expression

“…Larkfors et al [22] and others [23,24] have reported that NGF was decreased in the hippocampus of aging rats. Contrary results have been observed by several groups [25][26][27][28] however, including Hellweg et al [28], who found no decrease in NGF with age and no relationship between NGF expression and cognitive ability, as measured in the Morris water maze.…”

Patterns of Neurotrophin Protein Levels in Male and Female Fischer 344 Rats from Adulthood to Senescence: How Young is “Young” and How Old is “Old”?

“…Showing substantial variability, the age of the "aged" group has ranged from 18 to 33 months in different studies (Narisawa-Saito & Nawa, 1996;Yurek & Turner, 2001). The age of the young comparison group could also impact the young versus aged comparison, as underscored by research showing significant alterations in NGF and BDNF concentrations during early development (Katoh-Semba, 1997;Nishizuka et al, 1991). In some studies the age of the "young" group was 1 month (Katoh-Semba et al, 1998), 3 to 4 months (Nishizuka et al, 1991), 3 to 5 months (Bimonte, Nelson, & Granholm, 2002), or 4 to 5 months (Yurek & Turner, 2001), whereas others collapsed across 2 to 5 months olds (Scott et al, 1994).…”

“…Given recent evidence that neurotrophins are related to cognition in rodents, changes in neurotrophin levels may be a critical link in the cascade of biological alterations resulting in cognitive deterioration that occurs in aging and age-related neurodegenerative disorders (Kaisho, Ohta, Miyamato, & Igarashi, 1999;Mizuno, Yamada, Olariu, Nawa, & Nabeshima, 2000;Sugaya et al, 1998). Some studies show that patients with Alzheimer's disease (AD) exhibit alterations in NGF and BDNF in various brain regions compared to age-matched controls, although such effects are not consistently reported (see Siegel & Chauhan, 2000, for review (Nishizuka et al, 1991) or no change (Alberch, Perez-Navarro, Arenas, & Marsal, 1991;Crutcher & Weingartner, 1991;Katoh-Semba, Semba, Takeuchi, & Kato, 1998;Narisawa-Saito & Nawa, 1996;Scott, Liang, Weingartner, & Crutcher, 1994;Taglialatela, Robinson, Gegg, & Perez-Polo, 1997) in hippocampal NGF. Although strain differences in age-related neurotrophin changes may account for some of the discrepancy between rat studies, there are conflicting findings even when comparing studies using the same rat strain (Larkfors et al, 1988).…”

“…Still others did not specify the sex of subjects (Larkfors et al, 1988), or used both males and females yet did not include sex in the published analyses (KatohSemba et al, 1998). The importance of sex is highlighted by the reported sex differences in certain brain regions (e.g., the hippocampus) and biochemical systems (e.g., cholinergic and neurotrophic) known to degenerate during normal and disease-related aging (see Luine, Renner, & McEwen, 1986;Nishizuka et al, 1991, for examples). Hence, age-related changes in neurotrophin levels in males may not be generalizable to the age-related changes that occur in females.…”

“…Unfortunately, animal research has not clarified the direction of age-related neurotrophic alterations, or even whether changes do in fact occur. For example, compared to young rodents, aged rodents have exhibited both decreases (Nishizuka et al, 1991) or no change (Alberch, Perez-Navarro, Arenas, & Marsal, 1991;Crutcher & Weingartner, 1991;Katoh-Semba, Semba, Takeuchi, & Kato, 1998;Narisawa-Saito & Nawa, 1996;Scott, Liang, Weingartner, & Crutcher, 1994;Taglialatela, Robinson, Gegg, & Perez-Polo, 1997) in hippocampal NGF. Although strain differences in age-related neurotrophin changes may account for some of the discrepancy between rat studies, there are conflicting findings even when comparing studies using the same rat strain (Larkfors et al, 1988).…”