Table 1. Preclinical study characteristics.
| Author, year | Subjects | No. of subjects | Days of intervention | Bacterial species and dosage (CFU) | Anxiety measure |
|---|---|---|---|---|---|
| Agusti A, 2017 Group 1 | Male C57BL-6 mice | 20 | 98 | B. pseudocatenulatum CECT 7765 (1 x 109) | Open field test: ↔ time in center; Light-dark test: ↔ latency |
| Agusti A, 2017 Group 2 | Male C57BL-6 mice fed a high-fat diet | 20 | 98 | B. pseudocatenulatum CECT 7765 (1 x 109) | Open field test: ↔ time in center; Light-dark test: ↔ latency |
| Barrera-Bugueno C, 2017 | Male Sprague-Dawley rats | 18 | 14 | L. casei 54-2-33 (1 x 104 CFU/mL of drinking water) | Open field test: ↑ time in center, ↑ entries into center; Elevated plus maze: ↔ time in open arms, ↔ entries into open arms |
| Beilharz J, 2017 Group 1 | Male Sprague-Dawley rats | 30 | 36 | B. longum DSM 24736, B. infantis DSM 24737, B. breve DSM 24732, L. acidophilus DSM 24735, L. paracasei DSM 24733, L. bulgaricus DSM 24734, L. plantarum DSM 24730, Streptococcus thermophilus subsp. thermophilus DSM 24731 (Low dose– 2.5 x 109; High dose– 2.5 x 1010) | Elevated plus maze: ↔ time in open arms |
| Beilharz J, 2017 Group 2 | Male Sprague-Dawley rats fed a cafeteria diet | 29 | 36 | B. longum DSM 24736, B. infantis DSM 24737, B. breve DSM 24732, L. acidophilus DSM 24735, L. paracasei DSM 24733, L. bulgaricus DSM 24734, L. plantarum DSM 24730, Streptococcus thermophilus subsp. thermophilus DSM 24731 (Low dose– 2.5 x 109; High dose– 2.5 x 1010) | Elevated plus maze: ↔ time in open arms |
| Bercik P, 2010 | Male AKR mice infected with Trichuris muris | 42 | 30 | L. rhamnosus NCC4007 and B. longum NCC3001 (1 x 1010) | Light-dark box test: ↓ time in light box, ↔ latency to re-enter light box; Step-down test: ↓ latency |
| Bercik P, 2011 Group 1 | Male AKR mice exposed to dextran sodium sulfate | 23 | 14 | B. longum (1 x 1010) | Step-down test: ↓ latency |
| Bercik P, 2011 Group 2 | Vagotomized male AKR mice exposed to dextran sodium sulfate | 30 | 14 | B. longum (1 x 1010) | Step-down test: ↔ latency |
| Bharwani A, 2017 Group 1 | Male C57BL/6 mice | 30 | 28 | L. rhamnosus JB-1 (1.67 x 109) | Light-dark box test: ↔ entries into light zone |
| Bharwani A, 2017 Group 2 | Male C57BL/6 mice exposed to social defeat | 31 | 28 | L. rhamnosus JB-1 (1.67 x 109) | Light-dark box test: ↓ entries into light zone |
| Bravo J, 2011 | Male BALB/c mice | 36 | 28 | L. rhamnosus JB-1 (1 x 109) | Elevated plus maze: ↓ open arm entries, ↔ time in open arms |
| Cowan C, 2016 | Female Sprague-Dawley rats | 16 | 13 | L. rhamnosus R0011 and L. helveticus R0052 (1 x 109 CFU/mL of drinking water) | Elevated plus maze: ↔ open arm entries, ↔ time in open arms, ↔ latency |
| Divyashri G, 2015 | Male CFT-Swiss mice | 24 | 28 | Enterococcus faecium CFR 3003 (Low dose– 1 x 104; High dose– 1 x 108) or L. rhamnosus GG MTCC 1408 (1 x 108) | Elevated plus maze: ↓ open arm entries, ↓ time in open arms; Open field test: ↔ entries into center, ↔ time in center |
| Emge J, 2016 Group 1 | Male and female C57BL/6 mice | 10 | 15 | L. rhamnosus R0011 and L. helveticus R0052 (2 x 109) | Light-dark box test: ↔ time in light box |
| Emge J, 2016 Group 2 | Male and female C57BL/6 mice exposed to dextran sodium sulfate | 20 | 15 | L. rhamnosus R0011 and L. helveticus R0052 (2 x 109) | Light-dark box test: ↓ time in light box |
| Jang H, 2017 | Male ICR mice exposed to immobilization stress | 24 | 3 | B. adolescentis IM38 (Low dose– 2 x 108; Medium dose– 1 x 109; High dose– 5 x 109 CFU) | Elevated plus maze: ↓ open arm entries, ↓ time in open arms |
| Liang S, 2015 | Male specific-pathogen-free Sprague-Dawley rats exposed to chronic restraint stress | 16 | 22 | L. helveticus NS8 (1 x 109 CFU/mL of drinking water) | Elevated plus maze: ↔ open arm entries, ↓ time in open arms; Open field test: ↔ time in center |
| Liu W, 2016 Group 1 | Male GF C57BL/BJNarl mice | 20 | 16 | L. plantarum PS128 (1 x 109) | Elevated plus maze: ↓ time in open arms / time in closed arms ratio; Open field test: ↔ time in center |
| Liu W, 2016 Group 2 | Male C57BL/6J mice | 12 | 16 | L. plantarum PS128 (1 x 109) | Elevated plus maze: ↓ time in open arms; Open field test: ↓ time in center |
| Liu Y, 2016 Group 1 | Male C57BL/6J mice exposed to early-life stress | 20 | 28 | L. plantarum PS128 (1 x 109) | Elevated plus maze: ↔ time in open arms; Open field test: ↔ time in center |
| Liu Y, 2016 Group 2 | Male C57BL/6J mice | 18 | 28 | L. plantarum PS128 (1 x 109) | Elevated plus maze: ↓ time in open arms; Open field test: ↓ time in center |
| Luo J, 2014 | Male specific-pathogen-free Sprague-Dawley rats with induced hyperammonemia | 12 | 14 | L. helveticus NS8 (1 x 109) | Elevated plus maze: ↓ open arm entries, ↔ time in open arms |
| Mackos A, 2013 Group 1 | Male outbred CD-1 mice | 36 | 12 | L. reuteri 23272 (1.5 x 108) | Open field test: ↔ time spent in center |
| Mackos A, 2013 Group 2 | Male outbred CD-1 mice exposed to prolonged-restraint | 18 | 12 | L. reuteri 23272 (1.5 x 108) | Open field test: ↔ time spent in center |
| Matthews D, 2013 | Male specific-pathogen-free BALB/c mice | 18 | Administered several times over 7 weeks | Mycobacterium vaccae 15,483 (4.5 x 105) | Anxiety-like behaviors during maze task: ↔ immobilization, ↔ grooming, ↔ latency to start |
| McKernan D, 2010 Group 1 | Male Sprague-Dawley rats | 40 | 14 | L. salivarius UCC118 (1 x 109); or B. infantis 35624 (1 x 109); or B. breve UCC2003 (1 x 109) | Open field test: ↔ time in center |
| McKernan D, 2010 Group 2 | Male Wistar-Kyoto rats | 40 | 14 | L. salivarius UCC118 (1 x 109); or B. infantis 35624 (1 x 109); or B. breve UCC2003 (1 x 109) | Open field test: ↔ time in center |
| Moya-Perez A, 2017 Group 1 | Male C57Bl/6J mice | 18 | 20 | B. pseudocatenulatum CECT 7765 (1 x 108 CFU) | Elevated plus maze: ↔ time in open arms |
| Moya-Perez A, 2017 Group 2 | Male C57Bl/6J mice exposed to early-life stress | 18 | 20 | B. pseudocatenulatum CECT 7765 (1 x 108 CFU) | Elevated plus maze: ↓ time in open arms; Open field test: ↔ entries into center |
| Smith C, 2014 Group 1 | Male and female wild-type Rag1-/- mice | 12 | 28 | L. rhamnosus R0011 and L. helveticus R0052 (6 x 109) | Light-dark box test: ↓ time in light box |
| Smith C, 2014 Group 2 | Male and female wild-type Rag1-/- mice exposed to water avoidance stress | 10 | 28 | L. rhamnosus R0011 and L. helveticus R0052 (6 x 109) | Light-dark box test: ↓ time in light box |
| Vanhaecke T, 2017 | Sprague-Dawley rats | 12 | 15 | L. fermentum CECT 5716 (1 x 109 CFU/100g body weight) | Elevated plus maze: ↔ open arm entries |
| Wang T, 2015 | Male Sprague-Dawley rats exposed to an antibiotic | 20 | 30 | L. fermentum NS9 (1 x 109 CFU/mL of drinking water) | Elevated plus maze: ↓ open arm entries |
↓ and ↑ represent a statistically significant decrease or increase (respectively) in anxiety-like behavior in at least one probiotic treatment group, while ↔ represents a nonsignificant or unclear change.