GABA‐like immunoreactivity in Biomphalaria: Colocalization with tyrosine hydroxylase‐like immunoreactivity in the feeding motor systems of panpulmonate snails

Abstract

The simpler nervous systems of certain invertebrates provide opportunities to examine colocalized classical neurotransmitters in the context of identified neurons and well defined neural circuits. This study examined the distribution of γ-aminobutyric acid-like immunoreactivity (GABAli) in the nervous system of the panpulmonates Biomphalaria glabrata and Biomphalaria alexandrina, major intermediate hosts for intestinal schistosomiasis. GABAli neurons were localized in the cerebral, pedal, and buccal ganglia of each species. With the exception of a projection to the base of the tentacle, GABAli fibers were confined to the CNS. As GABAli was previously reported to be colocalized with markers for dopamine (DA) in five neurons in the feeding network of the euopisthobranch gastropod Aplysia californica (Díaz-Ríos, Oyola, & Miller, 2002), double-labeling protocols were used to compare the distribution of GABAli with tyrosine hydroxylase immunoreactivity (THli). As in Aplysia, GABAli-THli colocalization was limited to five neurons, all of which were located in the buccal ganglion. Five GABAli-THli cells were also observed in the buccal ganglia of two other intensively studied panpulmonate species, Lymnaea stagnalis and Helisoma trivolvis. These findings indicate that colocalization of the classical neurotransmitters GABA and DA in feeding central pattern generator (CPG) interneurons preceded the divergence of euopisthobranch and panpulmonate taxa. These observations also support the hypothesis that heterogastropod feeding CPG networks exhibit a common universal design.

Localization of keyhole limpet hemocyanin‐like immunoreactivity in the nervous system ofBiomphalaria alexandrina

“…In addition, GABA and possibly glycine might be expected to colocalize with VGAT (Chaudhry et al, ; McIntire, Reimer, Schuske, Edwards, & Jorgensen, ), but results obtained using antibodies against GABA and glycine produced different staining patterns from that observed for VGAT/KLH‐LIR (see Supporting Info. ); staining patterns produced by GABA were consistent with those in B. glabrata (Vaasjo et al, ) and shared similarities with other species (Díaz‐Ríos, Suess, & Miller, ; Gunaratne et al, ).…”

A central control circuit for encoding perceived food value

“…To test whether PRNs account for behavioral selection in vivo, we first identified the transmitter used by these cells to drive egestion. Previous mapping studies have revealed a single pair of unidentified dopaminergic neurons on the ventral surface of the buccal ganglia ( 20 , 21 ), and we hypothesized that these might be PRNs. Electrophysiology and double-labeling experiments using Alexa Fluor and dopamine antibody staining supported this idea ( Fig.…”

Melanin‐concentrating hormone peptidergic system: Comparative morphology between muroid species

“…Fronczek, Lammers, Balesar, Unmehopa, and Swaab () verified the specificity of the anti‐orexin antiserum by performing a dot blot test against a panel of 22 compounds, with only the orexin‐A well resulting in labeling. Vaasjo et al () report that the anti‐TH antibody used specifically labels neurons that are otherwise identified with several independent catecholaminergic markers, and Yew et al () performed an adsorption test with TH to show its specificity.…”