Serotonergic immunoreactivity in the pedal ganglia of the pulmonate snail Megalobulimus abbreviatus after thermal stimulus: A semi-quantitative analysis.
Using an immunohistochemical procedure and optical densitometry, the distribution of neurons containing serotonin (5-HT) was investigated in the pedal ganglia of Megalobulimus abbreviatus after thermal "non-functional stimulus" (22 degrees C) and stressful thermal conditions (50 degrees C). The animals were sacrificed at different times (3 h, 6 h and 24 h) following these stimuli. In control animals, the results showed the location of these serotonergic immunoreactive elements (5HT-ir) in this ganglion to be similar to those shown in other studies, where the anterior region of ventral sections showed the largest number of 5HT-ir neurons. In the anterior neurons, significant differences (p < 0.01) were observed between the groups of animals stimulated at 50 degrees C and 22 degrees C and sacrificed after 6 h. In the medial neurons, significant differences (p < 0.05) were observed between the control group and the groups of animals stimulated at 50 degrees C and sacrificed after 6 and 24 h. Neuropilar area 1 showed differences (p < 0.01) in 5HT-ir between the control group and the groups of animals stimulated at 50 degrees C and sacrificed after 3 and 24 h. Neuropilar area 2 showed a significant difference (p < 0.05) between the groups of animals stimulated at 22 degrees C and sacrificed after 3 and 24 h. These results suggest the involvement of 5-HT in the nociceptive circuit of M. abbreviatus, mainly that of the medial neurons and neuropilar area 1, which showed increases in 5HT-ir after thermal aversive stimuli. These results could be helpful in drawing cellular homologies with other gastropods.
Laboratório de Histofisiologia Comparada, Departamento de Ciências Morfológicas, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, RS, Brazil.
A
A
Swarowsky
A F
AF
Monteiro
L L
LL
Xavier
D M
DM
Zancan
M
M
Achaval
D000818:Animals; D017952:Ganglia, Invertebrate / Q000276:immunology* / Q000502:physiology; D006358:Hot Temperature; D007150:Immunohistochemistry; D009474:Neurons / Q000737:chemistry; D009619:Nociceptors / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D012908:Snails / Q000166:cytology / Q000502:physiology*
D012701:Serotonin