Proceedings zur Tagung der DVG-Fachgruppe „Physiologie und Biochemie“

ObjectiveGiven the progressively aging population and the associated increased risk of digestive disorders, which impose a significant individual and economic burden, it is essential to understand the underlying (patho-)physiological mechanisms.Age-related loss of neurons has been described in the enteric nervous system (ENS) of different mammalian species, whereas functional data (especially derived from the same individuum) on ENS activity and intestinal motor function are scarce.Since guinea pigs are widely used research models in the field of neurogastroenterology, we aimed to fill this gap of knowledge. MethodsThe colon of 27 guinea pigs, assigned to age group (ag) I (8 weeks old, n = 10), ag II (1 year old, n = 7) or ag III (2 years old, n = 10) was used to assess i) total neuronal numbers in myenteric plexus preparations stained for the pan neuronal marker HuCD, ii) colonic motility in organ bath experiments and iii) myenteric spontaneous and pharmacological stimulated neuronal activity using neuroimaging. ResultsHigher age was associated with both, a significant reduction in myenteric neuronal numbers and an altered myenteric neuronal and colonic motor activity.While spontaneous myenteric neuronal activity differed only marginally between the age groups, certain neuronal response parameters of nicotinergic as well as serotonergic responsiveness increased particularly in the time between 8 weeks and 12 months.In the organ bath setup, the contractile response to carbachol, added to circular-muscle-myenteric-plexus-preparations, was significantly smaller in age group III than in age group I. ConclusionsOur results confirm the already described reduction in myenteric neurons in the aging colon of various species, including the guinea pig.The concomitant assessment of neuronal and muscle activity showed a reduced cholinergic mediated contractile muscle response in the colon and increased neuronal activity in response to nicotinergic and serotonergic stimulation.This adds important information on age-related alterations of intestinal functions, while further research is needed to elucidate the impact of such findings for the in vivo situation.