Comparative neuroanatomical distribution and expression levels of neuropeptide F in the central nervous system of the female freshwater prawn, Macrobrachium rosenbergii, during the ovarian cycle

Abstract

Neuropeptide F (NPF) plays critical roles in controlling the feeding and reproduction of prawns. In the present study, we investigated changes in the expression levels of Macrobrachium rosenbergii neuropeptide F (MrNPF), and its neuroanatomical distribution in eyestalk (ES), brain (BR), subesophageal ganglion (SEG), thoracic ganglia (TG), and abdominal ganglia (AG), during the ovarian cycle of female prawn. By qRT-PCR, the amount of MrNPF transcripts exhibited a gradual increase in the ES, BR, and combined SEG and TG from stages I and II, to reach a maximum level at stage III, and slightly declined at stage IV, respectively. The highest to lowest expression levels were detected in combined SEG and TG, BR, ES, and AG, respectively. MrNPF immunolabeling was observed in several neuronal clusters, associated fibers, and neuropils of these central nervous system (CNS) tissues. MrNPF-ir was more intense in neurons and neuropils of SEG and TG than those found in other parts of the CNS. The number of MrNPFir neurons and intensity of MrNPF-ir were higher in the ES, BR, SEG, and TG at the late stages than those at the early stages of the ovarian cycle, while those in AG exhibited insignificant change. Taken together, there is a correlation between changes in the neuroanatomical distribution of MrNPF and stages of the ovarian cycle, implying that MrNPF may be an important neuropeptide that integrates sensory stimuli, including photo-, chemo-, and gustatory receptions, to control feeding and reproduction, particularly ovarian development, of this female prawn, M. rosenbergii.

Discovery of a hidden form of neuropeptide F and its presence throughout the CNS–gut axis in the mud crab, Scylla olivacea

“…Macro-NPF-ir was majorly detected in the CNS, including the neuron of clusters 2, 3, and 4 and neuropil ME, MI, MT, XO-SG complex of optic ganglion, a few neurons in cluster 6/7, AMPN, PMPN of the protocerebrum, neuronal cluster 9/11, neuropil ON and its accessory lobe, and OGTN of deutocerebrum, neuronal cluster 14/15, TN, AnN, and CN of tritocerebrum of the brain. This localization pattern was very similar to previous reports into M. rosenbergii, especially the extensive intensity of NPF-ir in the XO-SG complex and their fibers in the optic ganglion linking to the ON and associated neuronal cluster 9/11 of the brain via the PT (Thongrod et al, 2017;Tinikul et al, 2022). The distribution pattern showed similarity, especially in the optic ganglion; however, there is a small different pattern in the prawn's brain.…”

“…Moreover, NPF-ir was localized in the neuronal clusters associated with SEG, TG, AG, and their neuropils of VNC of S. olivacea. Compared to M. rosenbergii NPF-ir, the localization patterns in TG and AG were quite similar to this study (Thongrod et al, 2019;Tinikul et al, 2022). Interestingly, NPF-ir was originally reported in CoG of the mud crab, S. olivacea, including the neuropils and associated neurons.…”

“…Moreover, our study revealed a distinct localization pattern of short NPF (sNPF) in S. paramamosain which was found in several neuronal clusters throughout the cerebral ganglion, including the neurons of cluster 10 examined by in situ hybridization (Xu et al, 2022). It is possible that the pattern of its localization might not be similar, according to the difference propose in the neuronal function or stages of release of each species (Thongrod et al, 2017;Tinikul et al, 2022;Xu et al, 2022). The most abundant NPF-ir throughout the CNS could suggest that this neuropeptide might be involved in the roles in olfactory modulation and endocrine signaling controls (Tinikul et al, 2022).…”

“…The distribution pattern showed similarity, especially in the optic ganglion; however, there is a small different pattern in the prawn's brain. NPF-ir was found in a few neurons in cluster 6/7 of the mud crab, whereas its localization pattern was mainly in the small and medium-sized neurons of cluster 6 of the protocerebrum and mildly intense in the neurons of cluster 17 in M. rosenbergii (Thongrod et al, 2017;Tinikul et al, 2022). Moreover, our study revealed a distinct localization pattern of short NPF (sNPF) in S. paramamosain which was found in several neuronal clusters throughout the cerebral ganglion, including the neurons of cluster 10 examined by in situ hybridization (Xu et al, 2022).…”

“…It is possible that the pattern of its localization might not be similar, according to the difference propose in the neuronal function or stages of release of each species (Thongrod et al, 2017;Tinikul et al, 2022;Xu et al, 2022). The most abundant NPF-ir throughout the CNS could suggest that this neuropeptide might be involved in the roles in olfactory modulation and endocrine signaling controls (Tinikul et al, 2022). Moreover, NPF-ir was localized in the neuronal clusters associated with SEG, TG, AG, and their neuropils of VNC of S. olivacea.…”