Hericium erinaceus Improves Recognition Memory and Induces Hippocampal and Cerebellar Neurogenesis in Frail Mice during Aging

Abstract

Frailty is a geriatric syndrome associated with both locomotor and cognitive decline, implicated in both poor quality of life and negative health outcomes. One central question surrounding frailty is whether phenotypic frailty is associated with the cognitive impairment during aging. Using spontaneous behavioral tests and by studying the dynamic change during aging, we demonstrated that the two form of vulnerability, locomotor and recognition memory decline, develop in parallel and therefore, integration of the motoric and cognitive evaluations are imperative. We developed an integrated frailty index based on both phenotypic and recognition memory performances. Hericium erinaceus (H. erinaceus) is a medicinal mushroom that improves recognition memory in mice. By using HPLC-UV-ESI/MS analyses we obtained standardized amounts of erinacine A and hericenones C and D in H. erinaceus extracts, that were tested in our animal model of physiological aging. Two-month oral supplementation with H. erinaceus reversed the age-decline of recognition memory. Proliferating cell nuclear antigen (PCNA) and doublecortin (DCX) immunohistochemistry in the hippocampus and cerebellum in treated mice supported a positive effect of an H. erinaceus on neurogenesis in frail mice.

Keywords: Hericium erinaceus; aging; cognitive decline; erinacines; hericenones; medicinal mushrooms supplementation; neurogenesis; phenotypic frailty.

Figure 1

Comparative age between men and mice during their life span and the chosen experimental times (modified by Dutta and Sengupta, 2016).

Figure 2

Locomotor and cognitive parameters during aging. (A) Locomotor parameters: total distance, resting time, mean speed, and max speed measured in open arena during aging. (B) cognitive parameters: latency to first exit, exit number, and exploring time measured in emergence, and (C) cognitive parameters: discrimination index (DI) of the time of approaches and of the number of approaches measured in NOR test. Statistical results were performed by Anova for repeated measures: * vs. T0, # vs. T1, $ vs. T2, and £ vs. T3. For all symbols reported p < 0.05 (*, #, $, £), p < 0.01 (**, ##, $$, ££), p < 0.001 (***, ###, $$$).

Figure 3

Locomotor, cognitive, and LAC (locomotor and cognitive) decline during physiological aging in mice. Locomotor (panel (A)), cognitive (panel (B)), and LAC (panel (C)) Frailty Index during physiological aging in mice. Linear regressions of experimental points and statistical results were reported. p < 0.05 (*), p < 0.01 (**), p < 0.001 (***), p < 0.0001 (****).

Figure 4

ESI/MS spectrum of Erinacine A. Panel (top, right) reports calibration curves and linear regression curve for Erinacine A.

Figure 5

ESI/MS spectra of Hericenone C and D. Panels (top, right) report calibration curves for Hericenone C and D.

Figure 6

MS (Mass Spectrum) traces of He1 mycelium and Erinacine A (Rt 10,57) standard. Peak area of Erinacine A is pointed out.

Figure 7

UV (Ultra Violet) traces of He1 sporophore (top) and Hericenone C (Rt 42.57) and D (Rt 44.34) standards (bottom). Peak areas corresponding to Hericenone C and D are pointed out.

Figure 8

H. erinaceus improved recognition memory during mice aging. Value measured pre-supplementation (pre) and post-supplementation (post) on locomotor, recognition memory, and LAC (Locomotor and Cognitive) FI. p < 0.05 (*).

Figure 9

Panel (A) shows cell proliferating activity immunocytochemically detected by PCNA (Proliferating Cell Nuclear Antigen) labelling, observed at T5 after 2 months oral supplementation with He1 in both hippocampus and cerebellum, (a’–d’ and e’–h’, respectively), compared to control untreated mice (CTR) (a–h). Cell proliferation was significantly enhanced in He1 mice, with the labelling appearing more intense in the hippocampal DG granule cells and in CA3 pyramidal neurons (a’–d’) and in cerebellar molecular layer (e’–h’), compared to controls (a–d and e–h, respectively), predominantly localized in the DG granule cells and in CA3 pyramidal neurons, as also in the width of the cerebellar. Objective magnification: 20 x (a, e and a’, e’); 40 x (b–d, f–h and b’–d’, f’–h’); 100 x (insert in b–d, f–h, b’–d’, f’–h’). Panel (B) shows changes in the percentage of PCNA labelling index of hippocampal and cerebellar cells in He1 mice. p < 0.05 (*).

Figure 10

Panel (A) shows doublecortin (DCX) immunocytochemistry, observed at T5 after 2 months oral supplementation with He1 in hippocampus and cerebellum (b and d), compared to control mice (a and c). Objective magnification: 40 x (a–d); 100 x (inserts). Panel (B) shows the cell frequency percentage of DCX labelling in the hippocampal dentate gyrus and cerebellar molecular layer in control and He1 mice. p < 0.01 (**), p = 0.07 (·).