Is doping of cognitive performance an anti‐herbivore adaptation? Alkaloids inhibiting acetylcholinesterase as a case

Abstract

Citation: Ejsmond, M. J., and F. D. Provenza. 2018. Is doping of cognitive performance an anti-herbivore adaptation?Alkaloids inhibiting acetylcholinesterase as a case. Ecosphere 9(2):e02129. 10. 1002/ecs2.2129 Abstract. Historically, people who study interactions between plants and herbivores focused on the ecological costs and benefits of synthesizing secondary metabolites. These compounds have diverse functions including defenses against herbivores. Some plants produce alkaloids that act as acetylcholinesterase inhibitors, increasing both the level and duration of action of the neurotransmitter acetylcholine with potential toxic effects in insects and mammals. Yet, among a number of neuroactive plant chemicals, alkaloids that inhibit acetylcholinesterase (AIA) display nootropic activities, that is, positively affect cognition, learning, and memory in mammals. This creates a paradox: Neuroactive AIA, expected to punish herbivores, enhance cognition, learning, and memory. A prevailing view is AIA are pesticides that adversely affecting the nervous systems of herbivorous insects, and the positive influences in mammals are merely a byproduct of other functions. We review literature on the behavioral ecology of diet choice, food-aversion learning, and neurophysiological actions of AIA in mammals to provide a more comprehensive view of the adaptive significance of AIA. These compounds act as anti-herbivory defenses that influence flavor (taste plus odor) preference/aversion, the formation of memories, and the feeding behavior of mammalian herbivores. Thus, what appears from an insect standpoint to be an enigma makes sense for mammals: AIA enable mammalian herbivores to quickly learn and remember specific plant(s) and the locations where they ate those plant(s). We provide examples of AIA, synthesized by over 200 plant species in 16 families, which affect learning and memory in mammals. Using 36 examples of acetylcholinesterase inhibitors synthesized by plants in 58 families, we also show that acetylcholinesterase blockers contribute to antiherbivore chemical defense by affecting food-aversion learning and memory in mammalian herbivores. We provide an evolutionary rationale for why natural selection may favor synthesis of chemicals that positively affect mental functions of herbivores. Our hypothesis, which challenges the current view that plant chemical defenses are aimed solely at destabilizing herbivore physiology, facilitates a broader understanding of diet preferences and feeding behavior in mammalian herbivores.

Probing of mortality rate by staying alive: The growth‐reproduction trade‐off in a spatially heterogeneous environment

“…In plants, structural constraints of reproductive investment may lead to simultaneous growth and reproduction (Ioslovich & Gutman, ; Kozłowski & Ziółko, ). However, selection exerted by herbivores seems to be a more general explanation (see Janczur, ) as the great majority of plants synthesize defensive chemicals to defend from herbivores (Ejsmond & Provenza, ; Foley & Moore, ; Strauss, Rudgers, Lau, & Irwin, ). Growth accompanying reproduction can also be optimal in populations that grow indefinitely, and age‐specific mortality drops throughout life towards a constant value (Engen & Saether, ).…”

The Power of Electropenetrography in Enhancing Our Understanding of Host Plant-Vector Interactions

“…Host plant metabolites play an important role in deterring or minimizing herbivory, and host metabolites have been shown to impact pest insect behavior and host preference in hemipteran pests [49,50,51]. Plant metabolites can be constitutive or induced [52], and can have diverse functions, including: Defense against herbivores or pathogens [53], as a response to mechanical damage [54,55], and as a response to environmental stress [56].…”

Atividade de alcaloides inibidores da acetilcolinesterase no tratamento da doença de Alzheimer: uma revisão sistemática

“…Dessa forma, alguns alcaloides, que se apresentam como um grupo heterogêneo de metabólitos secundários com estrutura química composta praticamente de nitrogênio, carbono, hidrogênio, e, em alguns casos, de oxigênio, e que podem ser encontrados no meio ambiente de diversas formas, têm-se apresentado como potenciais ativos no tratamento da DA devido à capacidade de aumentar a neurotransmissão colinérgica e a inibição rapidamente reversível da AChE 3,4 . Além disso, é mencionado que eles seriam mais bem tolerados pelos mamíferos em comparação a substâncias sintéticas, além de apresentarem maior especificidade aos ligantes 5 . Portanto, o objetivo deste trabalho é descrever a atividade de inibição da enzima acetilcolinesterase, por meio de ativos extraídos de alcaloides naturais.…”