Comparing the Behavioural Effects of Exogenous Growth Hormone and Melatonin in Young and Old Wistar Rats

Abstract

Growth hormone (GH) and melatonin are two hormones with quite different physiological effects. Curiously, their secretion shows parallel and severe age-related reductions. This has promoted many reports for studying the therapeutic supplementation of both hormones in an attempt to avoid or delay the physical, physiological, and psychological decay observed in aged humans and in experimental animals. Interestingly, the effects of the external administration of low doses of GH and of melatonin were surprisingly similar, as both hormones caused significant improvements in the functional capabilities of aged subjects. The present report aims at discerning the eventual difference between cognitive and motor effects of the two hormones when administered to young and aged Wistar rats. The effects were tested in the radial maze, a test highly sensitive to the age-related impairments in working memory and also in the rotarod test, for evaluating the motor coordination. The results showed that both hormones caused clear improvements in both tasks. However, while GH improved the cognitive capacity and, most importantly, the physical stamina, the effects of melatonin should be attributed to its antioxidant, anxiolytic, and neuroprotective properties.

Effect of Germination and Illumination on Melatonin and Its Metabolites, Phenolic Content, and Antioxidant Activity in Mung Bean Sprouts

“…Thereafter, the concentration gradually declines with increasing age [ 16 ]. Supplementation with melatonin not only delays age-related impairments but also improves physical, physiological, and psychological capabilities [ 17 ]. The biosynthesis pathway of melatonin initiates from the biosynthesis of tryptophan, an amino acid, and is stimulated by darkness and inhibited by light.…”

Growth rate, feed intake, physiological responses and hormonal profile of Murrah buffaloes implanted melatonin during summer season

“…During hot humid season, the values of GH in control was significant (P<0.05) lower than the treatment group. GH improved the cognitive capacity and melatonin should be attributed to its antioxidant, anxiolytic and neuro-protective properties (Barcelo et al 2016). During chronic heat stress GH concentration decreased, whereas, depicted static concentration of GH during acute heat stress, due to GH act as a calorigenic hormone (Mitra et al 1972).…”

Atividade física e longevidade

“…Pacientes com Doença de Alzheimer e Parkinson mostram uma redução na "melatonina" (Chen et al, 2020), "GH" (Bianchi et al, 2017) e "IGF-1" (Gasperi e Castellano, 2010;Walser et al, 2021). A administração exógena de GH em níveis menores foi capaz de levar a melhora na mobilidade (atividade e velocidade de movimento) e cognição (memória de trabalho) em ratos jovens e velhos (Barceló et al, 2016).…”