Mechanical properties of skin and responsiveness of slowly adapting type I mechanoreceptors in rats at different ages.

Abstract

SUMMARY1. Slowly adapting type I (s.a. I) cutaneous mechanoreceptors were studied in young (3-4 months old) and adult (9-11 months old) rats. Trains of thirty repetitive mechanical stimuli with 0-1 s rise time, 1-9 s plateau phase, and 0-7 s interstimulus interval were applied. A feed-back mechanism maintained the force of stimulation at 20 mN during the plateau phases of stimuli and the contact force between stimuli at 0-5 mN.2. During the first few stimuli in a train residual indentation at contact force increased rapidly. Maximal indentation required to maintain the force of stimulation of 20 mN increased as well but to a smaller extent. Thus, the stroke amplitudes of individual stimuli decreased with increasing stimulus number.3. All displacement values in the group of adult rats were consistently reduced to 62+3 % of the respective values in the group of young rats, indicating a linear decrease in skin compliance in the force range of 0-5-20 mN. 4. Nervous responses to individual stimuli decreased from about 200 impulses for stimulus number 1 to about 60 impulses for stimulus number 30. Significant differences in the number of impulses between young and adult rats were observed from stimulus number 9 to number 16 only.5. It is concluded that the design of the s.a. I receptor allows maintained high tactile sensitivity in response to force-related stimuli irrespective of age-induced changes in mechanical properties of the skin and underlying tissues.

Responsiveness and ultrastructure of slowly adapting type I cutaneous mechanoreceptors in vitamin A deficient rats.

“…I receptors. In the accompanying paper (Baumann et al 1986) conditions were described where large differences in the compliance of the skin have no consistent effect on the responsiveness of s.a. I receptors.…”

“…However, the connexion between these two phenomena may be only coincidental. Pronounced age-related changes in skin compliance had only little effect on the responsiveness of touch corpuscles (Baumann et al 1986). In other studies reduced responsiveness coincided with reduced rather than increased skin compliance for example after chronic treatment with neomycin (Baumann et al 1984) and neonatal treatment with capsaicin (Baumann, Cervero, Hamann & Leung, 1985).…”

“…Recovery time between runs was at least 6 min. A detailed description of the method has been given in the accompanying paper (Baumann et al 1986). …”

“…The accompanying paper (Baumann, Hamann & Leung, 1986) is concerned with age-induced changes in the force transmission properties of the skin and its effect on the responsiveness of s.a. I receptors.…”

Neurotrophin‐3 signaling in mammalian Merkel cell development

“…Together with A␤ sensory nerve endings they form the slowly adapting Merkel nerve endings, which are sensitive to steady skin indentation. They transduce sensation for whisker deflection by monitoring velocity, amplitude, and direction (Baumann et al, 1986;Halata et al, 2003). In mammals, Merkel cells are assembled in large numbers in touch domes of hairy skin, touch spots of glabrous skin, and in the outer root sheath of various types of hair.…”