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Neural circuits containing olfactory neurons are involved in the prepulse inhibition of the startle reflex in rats.

Niu H, He X, Zhou T, Shi X, Zhang Q, Zhang Z, Qiao Y, Xu F, Hu M - Front Behav Neurosci (2015)

Bottom Line: Our results demonstrated that blockage of olfactory sensory input could disturb olfactory behavior.In the function studies, we demonstrated that blockage of olfactory sensory input could impair the pre-pulse inhibition of the startle response following decreased c-Fos expression in relevant brain regions during the PPI responses.Thus, these data suggest that the olfactory system participates in the PPI regulating fields and plays a role in the pre-pulse inhibition of the startle response in rats.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Xuzhou Medical College Xuzhou, China ; The Institute of Audiology and Speech Science, Xuzhou Medical Collage Xuzhou, China.

ABSTRACT
Many neuropsychiatric disorders, such as schizophrenia, have been associated with olfactory dysfunction and abnormalities in the prepulse inhibition (PPI) response to a startle reflex. However, whether these two abnormalities could be related is unclear. The present investigations were designed to determine whether theblockage of olfactory sensory input by zinc sulfate infusion in the olfactory naris (0.5 ml, 0.17 M, ZnE) can disturb the PPI response. Furthermore, a bilateral microinjection of lidocaine/MK801 in the olfactory bulb (OB) was administered to examine whether the blockage of olfactory sensory input could impair the PPI response. To identify the neural projection between olfaction and PPI-related areas, trans-synaptic retrograde tracing with the recombinant pseudorabies virus (PRV) was used. Our results demonstrated that blockage of olfactory sensory input could disturb olfactory behavior. In the function studies, we demonstrated that blockage of olfactory sensory input could impair the pre-pulse inhibition of the startle response following decreased c-Fos expression in relevant brain regions during the PPI responses. Furthermore, similar and more robust findings indicated that blockage of olfactory sensory input by microinjection of lidocaine/MK801 in the OB could impair the PPI response. In the circuit-level studies, we demonstrated that trans-synaptic retrograde tracing with PRV exhibited a large portion of labeled neurons in several regions of the olfactory cortices from the pedunculopontine tegmental nucleus (PPTg). Thus, these data suggest that the olfactory system participates in the PPI regulating fields and plays a role in the pre-pulse inhibition of the startle response in rats.

No MeSH data available.


Related in: MedlinePlus

The performance of ZnE-treated rats in a habituation/discrimination task and locomotion in an open field. (A,B) Odor habituation/ discrimination task. Values represent the mean ± SD (n = 8–10). * indicates p < 0.05. (C) Effect of ZnE treatment on the locomotor activity of rats in the open field. The rats were allowed to freely explore the open field for 5 min (mean ± SEM). There was no significant difference between the groups (F(2,21) = 0.005, p > 0.05). (D) The effect of ZnE treatment on the time spent in the central area of the open field. No differences were identified between the groups with respect to the time spent in the central area of the open field (F(2,21) = 0.897, p > 0.05) compared with the naïve control group.
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Figure 1: The performance of ZnE-treated rats in a habituation/discrimination task and locomotion in an open field. (A,B) Odor habituation/ discrimination task. Values represent the mean ± SD (n = 8–10). * indicates p < 0.05. (C) Effect of ZnE treatment on the locomotor activity of rats in the open field. The rats were allowed to freely explore the open field for 5 min (mean ± SEM). There was no significant difference between the groups (F(2,21) = 0.005, p > 0.05). (D) The effect of ZnE treatment on the time spent in the central area of the open field. No differences were identified between the groups with respect to the time spent in the central area of the open field (F(2,21) = 0.897, p > 0.05) compared with the naïve control group.

Mentions: Our primary goal was to test whether there is a causal relationship between PPI response impairment and olfactory deficiency. We first examined odor-guided behavior in an odor habituation/discrimination task, which enabled measurements of novel odor investigation, odor learning and memory (habituation), and odor discrimination within a single behavioral test (Yang and Crawley, 2009). In this test, the rats were presented with lemon and a control odor during five consecutive days and subsequently exposed to a novel odor (mint odor, see Section Materials and Methods). Analysis of variance, using the five habituation trial numbers as the within-subject factor and the experimental group as the between-subjects factor, identified significant main effects (F(4,160) = 50.869, p < 0.05) and interaction effects (F(20,160) = 2.015, p < 0.05). This finding indicated that habituation to the lemon odor progressed across successive trials and was affected by the different treatment methods. Post hoc analysis indicated that in the odor habituation experiments (Figures 1A,B), the animals in the naïve control and ZnE groups exhibited a significant decrease in the sniffing time from the first odor (lemon) presentation through the subsequent presentations of the same odor. This decrease in sniffing behavior suggested that the animals successfully habituated to the repeated lemon odor presentations. When the lemon odor was replaced by a novel odor (mint) in the discrimination test, pairwise comparisons indicated that the control animals spent more time investigating the mint odor than the mineral oil (p < 0.05), whereas the animals that received the ZnE application to the naris did not exhibit a significant difference in their sniffing times between the mint and control odors (Figures 1A,B). These results suggested that the animals that received the ZnE application exhibited impaired discrimination between familiar and novel odorants (p > 0.05).


Neural circuits containing olfactory neurons are involved in the prepulse inhibition of the startle reflex in rats.

Niu H, He X, Zhou T, Shi X, Zhang Q, Zhang Z, Qiao Y, Xu F, Hu M - Front Behav Neurosci (2015)

The performance of ZnE-treated rats in a habituation/discrimination task and locomotion in an open field. (A,B) Odor habituation/ discrimination task. Values represent the mean ± SD (n = 8–10). * indicates p < 0.05. (C) Effect of ZnE treatment on the locomotor activity of rats in the open field. The rats were allowed to freely explore the open field for 5 min (mean ± SEM). There was no significant difference between the groups (F(2,21) = 0.005, p > 0.05). (D) The effect of ZnE treatment on the time spent in the central area of the open field. No differences were identified between the groups with respect to the time spent in the central area of the open field (F(2,21) = 0.897, p > 0.05) compared with the naïve control group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373374&req=5

Figure 1: The performance of ZnE-treated rats in a habituation/discrimination task and locomotion in an open field. (A,B) Odor habituation/ discrimination task. Values represent the mean ± SD (n = 8–10). * indicates p < 0.05. (C) Effect of ZnE treatment on the locomotor activity of rats in the open field. The rats were allowed to freely explore the open field for 5 min (mean ± SEM). There was no significant difference between the groups (F(2,21) = 0.005, p > 0.05). (D) The effect of ZnE treatment on the time spent in the central area of the open field. No differences were identified between the groups with respect to the time spent in the central area of the open field (F(2,21) = 0.897, p > 0.05) compared with the naïve control group.
Mentions: Our primary goal was to test whether there is a causal relationship between PPI response impairment and olfactory deficiency. We first examined odor-guided behavior in an odor habituation/discrimination task, which enabled measurements of novel odor investigation, odor learning and memory (habituation), and odor discrimination within a single behavioral test (Yang and Crawley, 2009). In this test, the rats were presented with lemon and a control odor during five consecutive days and subsequently exposed to a novel odor (mint odor, see Section Materials and Methods). Analysis of variance, using the five habituation trial numbers as the within-subject factor and the experimental group as the between-subjects factor, identified significant main effects (F(4,160) = 50.869, p < 0.05) and interaction effects (F(20,160) = 2.015, p < 0.05). This finding indicated that habituation to the lemon odor progressed across successive trials and was affected by the different treatment methods. Post hoc analysis indicated that in the odor habituation experiments (Figures 1A,B), the animals in the naïve control and ZnE groups exhibited a significant decrease in the sniffing time from the first odor (lemon) presentation through the subsequent presentations of the same odor. This decrease in sniffing behavior suggested that the animals successfully habituated to the repeated lemon odor presentations. When the lemon odor was replaced by a novel odor (mint) in the discrimination test, pairwise comparisons indicated that the control animals spent more time investigating the mint odor than the mineral oil (p < 0.05), whereas the animals that received the ZnE application to the naris did not exhibit a significant difference in their sniffing times between the mint and control odors (Figures 1A,B). These results suggested that the animals that received the ZnE application exhibited impaired discrimination between familiar and novel odorants (p > 0.05).

Bottom Line: Our results demonstrated that blockage of olfactory sensory input could disturb olfactory behavior.In the function studies, we demonstrated that blockage of olfactory sensory input could impair the pre-pulse inhibition of the startle response following decreased c-Fos expression in relevant brain regions during the PPI responses.Thus, these data suggest that the olfactory system participates in the PPI regulating fields and plays a role in the pre-pulse inhibition of the startle response in rats.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Xuzhou Medical College Xuzhou, China ; The Institute of Audiology and Speech Science, Xuzhou Medical Collage Xuzhou, China.

ABSTRACT
Many neuropsychiatric disorders, such as schizophrenia, have been associated with olfactory dysfunction and abnormalities in the prepulse inhibition (PPI) response to a startle reflex. However, whether these two abnormalities could be related is unclear. The present investigations were designed to determine whether theblockage of olfactory sensory input by zinc sulfate infusion in the olfactory naris (0.5 ml, 0.17 M, ZnE) can disturb the PPI response. Furthermore, a bilateral microinjection of lidocaine/MK801 in the olfactory bulb (OB) was administered to examine whether the blockage of olfactory sensory input could impair the PPI response. To identify the neural projection between olfaction and PPI-related areas, trans-synaptic retrograde tracing with the recombinant pseudorabies virus (PRV) was used. Our results demonstrated that blockage of olfactory sensory input could disturb olfactory behavior. In the function studies, we demonstrated that blockage of olfactory sensory input could impair the pre-pulse inhibition of the startle response following decreased c-Fos expression in relevant brain regions during the PPI responses. Furthermore, similar and more robust findings indicated that blockage of olfactory sensory input by microinjection of lidocaine/MK801 in the OB could impair the PPI response. In the circuit-level studies, we demonstrated that trans-synaptic retrograde tracing with PRV exhibited a large portion of labeled neurons in several regions of the olfactory cortices from the pedunculopontine tegmental nucleus (PPTg). Thus, these data suggest that the olfactory system participates in the PPI regulating fields and plays a role in the pre-pulse inhibition of the startle response in rats.

No MeSH data available.


Related in: MedlinePlus