Effect of different glyphosate doses on the chemical coding of neurons of the enteric nervous system of the porcine descending colon

Abstract

Background: Neurons of the enteric nervous system are characterised by high neuronal plasticity, with their number likely to change in response to various endogenous and exogenous substances.

Materials and methods: Fifteen sexually immature gilts divided into 3 groups were used: control — animals receiving empty gelatin capsules; G1 — animals receiving a low dose of glyphosate — 0.05 mg/kg bw/day; G2 — animals receiving a higher dose of glyphosate—0.5 mg/kg/day in gelatin capsules orally for 28 days. Frozen sections were then subjected to the procedure of double immunofluorescent staining.

Results: With low-dose supplementation, no effect on the SP- and CART-positive neuron population was observed. However, a reduction in the number of VAChT-positive neurons in the internal submucosal plexus was described, while the number of CGRP-positive neurons increased in all enteric plexuses. In response to a high glyphosate dose, the quantitative variability of the neurons was significantly more pronounced than that for a low dose. There was an increase in the number of SP- and CGRP-positive neurons and a decrease in the number of VAChT-positive neurons in both the myenteric plexus and the submucosal plexuses. The response of CART-positive neurons was the weakest, as a high dose of glyphosate led to an increase in the number of neurons only in the myenteric plexus.

Conclusions: The above data show that glyphosate is an exogenous substance that affects neuronal populations of the enteric nervous system, in this case, the descending colon.