Углеродные нанотрубки (УНТ), благодаря своим уникальным свойствам (повышенным прочности,
гибкости, электро- и теплопроводности), очень перспективны для разных областей промышленности и
медицины. Однако, в литературе накапливаются сведения о токсичности для организма больших доз УНТ,
но практически не изучен вопрос о потенциальной токсичности их малых доз. Ранее мы показали, что даже
однократное интраназальное введение крысам взвеси однослойных УНТ (ОСУНТ) в малой дозе (4 мкг/кг)
оказывало иммунносупрессивный эффект, что выражалось в угнетении продукции мРНК большинства
цитокинов в селезёнке и мозге. При этом усиливалась экспрессия раннего гена c-fos в обонятельной
луковице и пириформной коре [Лосева Е.В. и др., 2016]. Цель настоящей работы состояла в исследовании
влияния небольших доз ОСУНТ при интраназальном введении на показатели поведения крыс в тестах на
тревожность («открытое поле», «свет-темнота», «приподнятый крестообразный лабиринт» (ПКЛ)) и
депрессию («вынужденное плавание»).
Крысам-самцам Вистар ежедневно интраназально вводили по 100 мкл взвеси ОСУНТ в
физиологическом растворе (ФР) в малой (5,2 мкг/кг, n=9) или средней (52 мкг/кг, n=8) дозах. Контрольным
крысам аналогично вводили по 100 мкл ФР (n=8). Был проведён межгрупповой анализ (тест Манна Уитни
для независимых групп) совокупности показателей поведения крыс в упомянутых тестах (по 5 мин в
каждом). Показано, что в тесте «открытое поле» через сутки после однократного введения ОСУНТ в обеих
дозах, снижалась исследовательская активность, и наблюдались симптомы тревожности, а на фоне
средней дозы ОСУНТ – и симптомы депрессивного поведения (длительные замирания). В тестах «свет-
темнота» и «ПКЛ» у крыс после 3-х или 4-х кратного введения обоих доз ОСУНТ наблюдалась активация
поведения в светлом отсеке или открытом рукаве, что выражалось в частом и длительном их посещении.
Под влиянием малой дозы ОСУНТ в этих тестах также увеличивалась вертикальная исследовательская
активность (стойки), горизонтальная исследовательская активность (свешивания) и двигательная
активность, а под влиянием средней дозы ОСУНТ в ПКЛ усиливалось депрессивное поведение
(длительные замирания и долгий латентный период захода в закрытый рукав). В тесте «вынужденное
плавание» после 5-кратного введения обеих доз ОСУНТ увеличивалась длительность иммобильности и
уменьшалась длительность плавания, что может свидетельствовать о депрессивном поведении. То есть,
даже непродолжительное интраназальное введение небольших доз ОСУНТ может изменить поведение
животных, вызывая тревожно-депрессивное состояние и/или гиперактивацию поведенческих реакций.
Предполагается, что изменения в поведении крыс после интраназального введения ОСУНТ могут быть
связаны с частичным их проникновением в мозг, приводящим к нейродегенерации и/или нейровоспалению.
Необходимы дальнейшие исследования для выяснения механизмов, лежащих в основе поведенческих
изменений, вызываемых интраназальным введением ОСУНТ.
Работа поддержана Российской Академией Наук.

Carbon nanotubes (CNT) are very promising for different fields of industry and medicine due to their unique
properties (increased strength, flexibility, electrical and thermal conductivity). However, in literature, while the data
on toxicity for the organism of large doses of CNT are being accumulated, the question of the potential toxicity of
their small doses has not been studied in practice. Previously, we showed that even a single intranasal injection of
single-walled CNT (SWCNT) in a small dose (4 μg / kg) to rats had an immunosuppressive effect, which was
expressed in the inhibition of mRNA production of most cytokines in the spleen and brain. At the same time, the
expression of the early c-fos gene was enhanced in the olfactory bulb and the pyriform cortex [Loseva E.V. et al.,
2016]. The purpose of this work was to study the effect of SWCNT in small doses after intranasal injections on the
rat behavior in anxiety tests (open field, light-darkness, elevated plus maze (EPM)) and depression test (forced
swimming).
Male Wistar rats were injected daily with 100 μl of SWCNT suspensions in physiological saline in small (5.2
μg / kg, n = 9) or medium (52 μg / kg, n = 8) doses. Control rats received100 μl of physiological saline (n = 8) in the
same manner. A statistical analysis (Mann-Whitney test for independent groups) of the set of rat behavior signs in
these tests (5 min each) was carried out. It was shown that, in the "open field" test, one day after a single injection
of SWCNT in both doses exploratory activity decreased anxiety symptoms were observed, and after injection of a
medium dose of SWCNT symptoms of depressive behavior (long freezing) were observed. In "light-darkness" and
EPM tests in rats after 3 or 4-fold injections of both doses of SWCNT, behavior activation was observed in the light
box or open arms, which was expressed in their frequent and prolonged visitation. Under the influence of a small
dose of SWCNT, vertical exploratory activity (rears), horizontal exploratory activity (head dips) and motor activity
also increased in these tests, and under the influence of the medium dose of SWCNT in EPM, depressive behavior
(prolonged freezing and long latent period of going into the closed arms) increased. In the "forced swimming" test
after 5-fold injections of bothdecreased, which may indicate a depressive behavior. That is, even a short intranasal administration of small
doses of SWCNT can change the behavior of animals, causing anxiety-depressive state and / or hyperactivation of
behavioral reactions. It is suggested that changes in the behavior of rats after intranasal administration of SWCNT
may be associated with partial penetration into the brain leading to neurodegeneration and / or neuroinflammation.
Further studies are needed to elucidate the mechanisms underlying the behavioral changes caused by intranasal
administration of SWCNT. Work was supported by the Russian Academy of Sciences.

Carbon nanotubes (CNT) are very promising for different fields of industry and medicine due to their unique
properties (increased strength, flexibility, electrical and thermal conductivity). However, in literature, while the data
on toxicity for the organism of large doses of CNT are being accumulated, the question of the potential toxicity of
their small doses has not been studied in practice. Previously, we showed that even a single intranasal injection of
single-walled CNT (SWCNT) in a small dose (4 μg / kg) to rats had an immunosuppressive effect, which was
expressed in the inhibition of mRNA production of most cytokines in the spleen and brain. At the same time, the
expression of the early c-fos gene was enhanced in the olfactory bulb and the pyriform cortex [Loseva E.V. et al.,
2016]. The purpose of this work was to study the effect of SWCNT in small doses after intranasal injections on the
rat behavior in anxiety tests (open field, light-darkness, elevated plus maze (EPM)) and depression test (forced
swimming).
Male Wistar rats were injected daily with 100 μl of SWCNT suspensions in physiological saline in small (5.2
μg / kg, n = 9) or medium (52 μg / kg, n = 8) doses. Control rats received100 μl of physiological saline (n = 8) in the
same manner. A statistical analysis (Mann-Whitney test for independent groups) of the set of rat behavior signs in
these tests (5 min each) was carried out. It was shown that, in the "open field" test, one day after a single injection
of SWCNT in both doses exploratory activity decreased anxiety symptoms were observed, and after injection of a
medium dose of SWCNT symptoms of depressive behavior (long freezing) were observed. In "light-darkness" and
EPM tests in rats after 3 or 4-fold injections of both doses of SWCNT, behavior activation was observed in the light
box or open arms, which was expressed in their frequent and prolonged visitation. Under the influence of a small
dose of SWCNT, vertical exploratory activity (rears), horizontal exploratory activity (head dips) and motor activity
also increased in these tests, and under the influence of the medium dose of SWCNT in EPM, depressive behavior
(prolonged freezing and long latent period of going into the closed arms) increased. In the "forced swimming" test
after 5-fold injections of bothdecreased, which may indicate a depressive behavior. That is, even a short intranasal administration of small
doses of SWCNT can change the behavior of animals, causing anxiety-depressive state and / or hyperactivation of
behavioral reactions. It is suggested that changes in the behavior of rats after intranasal administration of SWCNT
may be associated with partial penetration into the brain leading to neurodegeneration and / or neuroinflammation.
Further studies are needed to elucidate the mechanisms underlying the behavioral changes caused by intranasal
administration of SWCNT. Work was supported by the Russian Academy of Sciences.