Postnatal development, electrophysiology, and sensory sural nerves

Role of tactile stimulation during the preweaning period on the development of the peripheral sensory sural (SU) nerve in adult artificially reared female rat

“…Indeed, although tactile stimuli did not prevent the effects of AR on myelin thickness, the main histological parameter proposed to be responsible of the disturbance of the CAP of the SU nerve (see Melo et al, 2021) and the frequency distribution of the myelin thickness (Figure 4i) were not significantly different from those of the SU nerves of MR females. Thus, we believe that tactile stimulation participates in the development of myelination of the SU nerve of female rats, but that this stimulus affects females differently than males, suggesting a sexually dimorphic effect.…”

Mother and sibling interactions during the preweaning period influence myelination and impulse propagation of the sensory sural nerve in the adult rat

“…It should be noted that the reduced myelination observed in rats reared in extreme litter sizes (1P, 3P, and 12P) may be associated with several axonal perturbations that disturb the propagation of action potentials (Kimura & Itami, 2009; Waxman et al, 1995). Since the SUn is mainly composed of myelinated sensory axons, disturbances in the axonal propagation of action potentials due to a lack of myelin could be expected to result in peripheral neuropathies (Melo et al., 2021). Consequently, it could be expected that a relatively large proportion of axons in nerves with peripheral neuropathy would present conduction block or intermittent propagation, which could account for the reduced area of the CAP observed in the SUn of rats from 1P, 3P, and 12P litters.…”

“…It should be noted that the reduced myelination observed in rats reared in extreme litter sizes (1P, 3P, and 12P) may be associated with several axonal perturbations that disturb the propagation of action potentials (Kimura & Itami, 2009;Waxman et al, 1995). Since the SUn is mainly composed of myelinated sensory axons, disturbances in the axonal propagation of action potentials due to a lack of myelin could be expected to result in peripheral neuropathies (Melo et al, 2021). Consequently, it could be expected that a relatively large proportion of axons in nerves with peripheral neuropathy would present Thus, the alteration of sensory nerve functionality found in offspring that did not receive adequate sensory and social stimulation during critical periods of development, either due to being deprived of the mother and littermates (Segura et al, 2014;Zempoalteca et al, 2018) or because they were raised in litters of extreme size (this study), resulting in poorer early nutrition, could explain certain neuropathies or even disturbances in social interactions due to the fact that social signals do not reach adequately the CNS and therefore the interpretation and response to these signals may be correspondingly inadequate.…”

“…The main branch of the SUn is practically a pure sensory nerve, containing approximately 1000–1300 myelinated axons (Segura et al., 2001) and few motor axons (Liguori & Trojabodrg, 2004). In rats, it is located immediately under the skin, traveling between the two heads of the gastrocnemius muscle, running in parallel to the lateral saphenous vein (Melo et al., 2021).…”

“…The main branch of the SUn is practically a pure sensory nerve, containing approximately 1000-1300 myelinated axons (Segura et al, 2001) and few motor axons (Liguori & Trojabodrg, 2004). In rats, it is located immediately under the skin, traveling between the two heads of the gastrocnemius muscle, running in parallel to the lateral saphenous vein (Melo et al, 2021). Segura et al (2014) found that artificially reared rat pups deprived of sensory feedback from their mother and littermates showed as adults a significant decrement in the area of the compound action potential (CAP), which has been considered a representative index of the number of axons activated in nerves (Stys et al, 1991), and a significant reduction in myelin thickness of axons in the SUn.…”