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

Abstract

To investigate whether mother and sibling interactions during the preweaning period influence the histological and electrophysiological characteristics of the sensory sural nerve (SUn) in the adult rat, litters composed of 1, 3, 6, 9, and 12 male pups (P) were formed and the pups routinely weighed until postnatal day 60 (PND60). At PND9, 3P and 6P litters showed greater body weight than pups without siblings or from 9P or 12P litters, and such differences in weight were maintained until adulthood. Analysis of maternal licking at PND8 and 9 showed that pups from large litters received fewer licks than pups from small size litters. At PND60, SUn of rats from 6P and 9P litters had greater compound action potential (CAP) amplitude and a higher proportion of axons with large myelin thickness than nerves from rats of 1P, 3P, or 12P litters. SUn of heaviest rats from 9P and 12P litters had greater CAP area and myelination than the lightest rats from the same litters. We propose that a complex interplay of sensory, social, and nutritional factors arising from mother and littermate interactions during the preweaning period influence myelination and the propagation of action potentials in the SUn of adult rats.

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

“…Furthermore, significant reductions in the outer diameter and myelin thickness of axons were also observed in AR rats. In addition, a semiquantitative deconvolution‐like procedure developed by our group (Martínez‐Alvárez et al., 2022) reveals the probable presence of a large proportion of axons with low myelin thickness in nerves of AR rats as compared to the nerves of the MR and AR‐tactile groups of rats.…”

“…As several percent distributions of the histological parameters measured in the SU nerves seem not to follow a single binomial distribution but rather a bimodal distribution (with two peaks), we decided to use a simple deconvolution‐like, semiquantitative procedure developed previously by our group (Martínez‐Álvarez et al., 2022). Briefly, such procedure assumed that the presence of two peaks in the total percent frequency distribution indicated the occurrence of two subpopulations of axons (Subp.…”

“…The sum of the percent frequency values of each Subp. A and B curves corresponds to the percentage of axons with relatively small or large diameters (outer or inner) or myelin thickness of axons, respectively (for a more detailed description of the deconvolution‐like procedure, see supplementary material in Martínez‐Álvarez et al., 2022).…”