Limits...
Quantification of dendritic and axonal growth after injury to the auditory system of the adult cricket Gryllus bimaculatus.

Pfister A, Johnson A, Ellers O, Horch HW - Front Physiol (2013)

Bottom Line: However, the cues that maintain or influence adult neuronal morphology are less well understood.In males, however, dendritic growth rates were linear, with dendrites growing steadily over time and reaching lengths, on average, twice as long as in females.On the other hand, rates of N5 axonal growth showed no significant sexual dimorphism and were linear.

View Article: PubMed Central - PubMed

Affiliation: Department of Invertebrate Zoology, American Museum of Natural History New York, NY, USA.

ABSTRACT
Dendrite and axon growth and branching during development are regulated by a complex set of intracellular and external signals. However, the cues that maintain or influence adult neuronal morphology are less well understood. Injury and deafferentation tend to have negative effects on adult nervous systems. An interesting example of injury-induced compensatory growth is seen in the cricket, Gryllus bimaculatus. After unilateral loss of an ear in the adult cricket, auditory neurons within the central nervous system (CNS) sprout to compensate for the injury. Specifically, after being deafferented, ascending neurons (AN-1 and AN-2) send dendrites across the midline of the prothoracic ganglion where they receive input from auditory afferents that project through the contralateral auditory nerve (N5). Deafferentation also triggers contralateral N5 axonal growth. In this study, we quantified AN dendritic and N5 axonal growth at 30 h, as well as at 3, 5, 7, 14, and 20 days after deafferentation in adult crickets. Significant differences in the rates of dendritic growth between males and females were noted. In females, dendritic growth rates were non-linear; a rapid burst of dendritic extension in the first few days was followed by a plateau reached at 3 days after deafferentation. In males, however, dendritic growth rates were linear, with dendrites growing steadily over time and reaching lengths, on average, twice as long as in females. On the other hand, rates of N5 axonal growth showed no significant sexual dimorphism and were linear. Within each animal, the growth rates of dendrites and axons were not correlated, indicating that independent factors likely influence dendritic and axonal growth in response to injury in this system. Our findings provide a basis for future study of the cellular features that allow differing dendrite and axon growth patterns as well as sexually dimorphic dendritic growth in response to deafferentation.

No MeSH data available.


Related in: MedlinePlus

Initial AN growth across the midline increased more rapidly in females than males over time after deafferentation. (A) AN dendritic maximum perpendicular extent, (B) longest dendrite, and (C) skeletal length increased non-linearly in females (red) and linearly in males (blue). Dendritic length in females reached a plateau by 3 days after deafferentation, while male dendritic length increased more slowly and did not plateau within the measured time period. The mean for each time point is shown as a slightly larger data point, and error bars represent standard error of the mean. The blue and red shaded areas represent 95% confidence intervals. Female AN control (n = 4), 30 h (n = 9), 3 days (n = 4), 5 days (n = 4), 7 days (n = 7), 14 days (n = 1), and 20 days (n = 9). Male AN control (n = 5), 30 h (n = 4), 3 days (n = 6), 5 days (n = 8), 7 days (n = 7), 14 days (n = 6), and 20 days (n = 3). See Table 1 for regression equations and statistics.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3750946&req=5

Figure 3: Initial AN growth across the midline increased more rapidly in females than males over time after deafferentation. (A) AN dendritic maximum perpendicular extent, (B) longest dendrite, and (C) skeletal length increased non-linearly in females (red) and linearly in males (blue). Dendritic length in females reached a plateau by 3 days after deafferentation, while male dendritic length increased more slowly and did not plateau within the measured time period. The mean for each time point is shown as a slightly larger data point, and error bars represent standard error of the mean. The blue and red shaded areas represent 95% confidence intervals. Female AN control (n = 4), 30 h (n = 9), 3 days (n = 4), 5 days (n = 4), 7 days (n = 7), 14 days (n = 1), and 20 days (n = 9). Male AN control (n = 5), 30 h (n = 4), 3 days (n = 6), 5 days (n = 8), 7 days (n = 7), 14 days (n = 6), and 20 days (n = 3). See Table 1 for regression equations and statistics.

Mentions: A small number of AN dendrites normally extended a short distance across the midline in control crickets (T = 0, Figure 3A); however, dendrites in deafferented crickets rapidly extended further across the midline. AN growth patterns were significantly and strikingly different in male and female crickets. In males, the maximum perpendicular extent, the longest dendrite, and the skeletal length each increased linearly following deafferentation. In females, however, growth of each of these variables increased non-linearly and were characterized by a rapid growth phase in the first 3 days followed by a plateau in length (Figures 3A–C; Table 1). In general, female data were less variable than male data (Table 1). While at day 0 there were no significant differences in dendritic characteristics (t-tests, each df = 10, each p > 0.3; see also 95% confidence intervals of linear and non-linear fits), by day 20, all dendritic characteristics were 45–110% greater in males than in females (Table 1).


Quantification of dendritic and axonal growth after injury to the auditory system of the adult cricket Gryllus bimaculatus.

Pfister A, Johnson A, Ellers O, Horch HW - Front Physiol (2013)

Initial AN growth across the midline increased more rapidly in females than males over time after deafferentation. (A) AN dendritic maximum perpendicular extent, (B) longest dendrite, and (C) skeletal length increased non-linearly in females (red) and linearly in males (blue). Dendritic length in females reached a plateau by 3 days after deafferentation, while male dendritic length increased more slowly and did not plateau within the measured time period. The mean for each time point is shown as a slightly larger data point, and error bars represent standard error of the mean. The blue and red shaded areas represent 95% confidence intervals. Female AN control (n = 4), 30 h (n = 9), 3 days (n = 4), 5 days (n = 4), 7 days (n = 7), 14 days (n = 1), and 20 days (n = 9). Male AN control (n = 5), 30 h (n = 4), 3 days (n = 6), 5 days (n = 8), 7 days (n = 7), 14 days (n = 6), and 20 days (n = 3). See Table 1 for regression equations and statistics.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750946&req=5

Figure 3: Initial AN growth across the midline increased more rapidly in females than males over time after deafferentation. (A) AN dendritic maximum perpendicular extent, (B) longest dendrite, and (C) skeletal length increased non-linearly in females (red) and linearly in males (blue). Dendritic length in females reached a plateau by 3 days after deafferentation, while male dendritic length increased more slowly and did not plateau within the measured time period. The mean for each time point is shown as a slightly larger data point, and error bars represent standard error of the mean. The blue and red shaded areas represent 95% confidence intervals. Female AN control (n = 4), 30 h (n = 9), 3 days (n = 4), 5 days (n = 4), 7 days (n = 7), 14 days (n = 1), and 20 days (n = 9). Male AN control (n = 5), 30 h (n = 4), 3 days (n = 6), 5 days (n = 8), 7 days (n = 7), 14 days (n = 6), and 20 days (n = 3). See Table 1 for regression equations and statistics.
Mentions: A small number of AN dendrites normally extended a short distance across the midline in control crickets (T = 0, Figure 3A); however, dendrites in deafferented crickets rapidly extended further across the midline. AN growth patterns were significantly and strikingly different in male and female crickets. In males, the maximum perpendicular extent, the longest dendrite, and the skeletal length each increased linearly following deafferentation. In females, however, growth of each of these variables increased non-linearly and were characterized by a rapid growth phase in the first 3 days followed by a plateau in length (Figures 3A–C; Table 1). In general, female data were less variable than male data (Table 1). While at day 0 there were no significant differences in dendritic characteristics (t-tests, each df = 10, each p > 0.3; see also 95% confidence intervals of linear and non-linear fits), by day 20, all dendritic characteristics were 45–110% greater in males than in females (Table 1).

Bottom Line: However, the cues that maintain or influence adult neuronal morphology are less well understood.In males, however, dendritic growth rates were linear, with dendrites growing steadily over time and reaching lengths, on average, twice as long as in females.On the other hand, rates of N5 axonal growth showed no significant sexual dimorphism and were linear.

View Article: PubMed Central - PubMed

Affiliation: Department of Invertebrate Zoology, American Museum of Natural History New York, NY, USA.

ABSTRACT
Dendrite and axon growth and branching during development are regulated by a complex set of intracellular and external signals. However, the cues that maintain or influence adult neuronal morphology are less well understood. Injury and deafferentation tend to have negative effects on adult nervous systems. An interesting example of injury-induced compensatory growth is seen in the cricket, Gryllus bimaculatus. After unilateral loss of an ear in the adult cricket, auditory neurons within the central nervous system (CNS) sprout to compensate for the injury. Specifically, after being deafferented, ascending neurons (AN-1 and AN-2) send dendrites across the midline of the prothoracic ganglion where they receive input from auditory afferents that project through the contralateral auditory nerve (N5). Deafferentation also triggers contralateral N5 axonal growth. In this study, we quantified AN dendritic and N5 axonal growth at 30 h, as well as at 3, 5, 7, 14, and 20 days after deafferentation in adult crickets. Significant differences in the rates of dendritic growth between males and females were noted. In females, dendritic growth rates were non-linear; a rapid burst of dendritic extension in the first few days was followed by a plateau reached at 3 days after deafferentation. In males, however, dendritic growth rates were linear, with dendrites growing steadily over time and reaching lengths, on average, twice as long as in females. On the other hand, rates of N5 axonal growth showed no significant sexual dimorphism and were linear. Within each animal, the growth rates of dendrites and axons were not correlated, indicating that independent factors likely influence dendritic and axonal growth in response to injury in this system. Our findings provide a basis for future study of the cellular features that allow differing dendrite and axon growth patterns as well as sexually dimorphic dendritic growth in response to deafferentation.

No MeSH data available.


Related in: MedlinePlus