Immunohistochemical Observation of Pituitary Adenylate Cyclase–activating Polypeptide (PACAP) and Adenohypophysial Hormones in the Pituitary of a Teleost, Uranoscopus japonicus

Matsuda, Kouhei; Nagano, Yoshinobu; Uchiyama, Minoru; Takahashi, Akiyoshi; Kawauchi, Hiroshi

doi:10.2108/zsj.22.71

Cited by 15 publications

(4 citation statements)

References 35 publications

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“…Similar results have been achieved even with antisera against hormones of non-closely-related species, e.g. in gilthead seabream (anti-Mediterranean-yellowtail antisera; García Ayala et al 2003) and Uranoscopus japonicus (antichum-salmon antisera; Matsuda et al 2005). These studies and our own have revealed a distribution pattern similar to that obtained by in situ hybridisation with species-specific probes.…”

Section: Discussionsupporting

confidence: 86%

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

et al. 2006

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Fish pituitary plays a central role in the control of growth, development, reproduction and adaptation to the environment. Several types of hormone-secreting adenohypophyseal cells have been characterised and localised in diverse teleost species. The results suggest a similar distribution pattern among the species investigated. However, most studies deal with a single hormone or hormone family. Thus, we studied adjacent sections of the pituitary of Oreochromis niloticus, the tilapia, by conventional staining and immunohistochemistry with specific antisera directed against growth hormone (GH), prolactin (PRL), somatolactin (SL), thyrotropin (beta-TSH), follicle-stimulating hormone (beta-FSH), luteinising hormone (beta-LH), adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (alpha-MSH). The pituitary was characterised by a close interdigitating neighbourhood of neurohypophysis (PN) and adenohypophysis. PRL-immunoreactive and ACTH-immunoreactive cells were detected in the rostral pars distalis. GH-immunoreactive cells were present in the proximal pars distalis (PPD). A small region of the PPD contained beta-TSH-immunoreactive cells, and beta-LH-immunoreactive cells covered approximately the remaining parts. Centrally, beta-FSH-immunoreactive cells were detected in the vicinity of the GH-containing cells. Some of these cells also displayed beta-LH immunoreactivity. The pars intermedia was characterised by branches of the PN surrounded by SL-containing and alpha-MSH-immunoreactive cells. The ACTH and alpha-MSH antisera were observed to cross-react with the respective antigens. This cross-reactivity was abolished by pre-absorption. We present a complete map of the distinct localisation sites for the classical pituitary hormones, thereby providing a solid basis for future research on teleost pituitary.

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Section: Discussionsupporting

confidence: 86%

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

et al. 2006

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“…In representative fish species, PACAP immunoreactivity can be detected in the posterior pituitary, e.g., in goldfish (43) and European eels (26). In stargazer, PACAP nerve fibers are located in close proximity to SL cells in the pars intermedia (22), suggesting that the peptide may play a role in SL regulation. In a recent study (23) in goldfish using a cell immunoblot assay, PACAP treatment was shown to increase the immunoblot area for SL immunoreactivity in individual pituitary cells, implying that PACAP may act as a stimulator to trigger SL release at the pituitary level.…”

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Grass carp somatolactin: I. Evidence for PACAP induction of somatolactin-α and -β gene expression via activation of pituitary PAC-I receptors

Jiang

Ko²,

Lerner³

et al. 2008

American Journal of Physiology-Endocrinology and Metabolism

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Somatolactin (SL), the latest member of the growth hormone/prolactin family, is a novel pituitary hormone with diverse functions. At present, SL can be identified only in fish but not in tetrapods and its regulation at the pituitary level has not been fully characterized. Using grass carp as a model, we examined the direct effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on SL secretion and synthesis at the pituitary cell level. As a first step, the structural identity of grass carp SL, SLalpha and SLbeta, was established by 5'/3'-rapid amplification of cDNA ends. These two SL isoforms are single-copy genes and are expressed in two separate populations of pituitary cells located in the pars intermedia. In the carp pituitary, PACAP nerve fibers were detected in the nerve tracts of the neurohypophysis and extended into the vicinity of pituitary cells forming the pars intermedia. In primary cultures of grass carp pituitary cells, PACAP was effective in stimulating SL release, cellular SL content, and total SL production. The increase in SL production also occurred with parallel rises in SLalpha and SLbeta mRNA levels. With the use of a combination of molecular and pharmacological approaches, PACAP-induced SL release and SL gene expression were shown to be mediated by pituitary PAC-I receptors. These findings, as a whole, suggest that PACAP may serve as a hypophysiotropic factor in fish stimulating SL secretion and synthesis at the pituitary level. Apparently, PACAP-induced SL production is mediated by upregulation of SLalpha and SLbeta gene expression through activation of PAC-I receptors.

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“…In stargazer, PACAP nerve fibers are located in the vicinity of SL cells in the pars intermedia (20). With the use of a cell immunoblot assay, the blotting area for SL immunoreactivity detected on the culture membrane with goldfish pituitary cells attached can be increased by PACAP treatment, implying that PACAP may induce SL release at the pituitary level (21).…”

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Grass carp somatolactin: II. Pharmacological study on postreceptor signaling mechanisms for PACAP-induced somatolactin-α and -β gene expression

Jiang

He²,

Wang³

et al. 2008

American Journal of Physiology-Endocrinology and Metabolism

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Somatolactin (SL), the latest member of the growth hormone/prolactin family, is a novel pituitary hormone with diverse functions. However, the signal transduction mechanisms responsible for SL expression are still largely unknown. Using grass carp as an animal model, we examined the direct effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on SL gene expression at the pituitary level. In primary cultures of grass carp pituitary cells, SL␣ and SL␤ mRNA levels could be elevated by PACAP via activation of PAC-I receptors. With the use of a pharmacological approach, the AC/cAMP/PKA and PLC/inositol 1,4,5-trisphosphate (IP 3)/PKC pathways and subsequent activation of the Ca 2ϩ /calmodulin (CaM)/CaMK-II cascades were shown to be involved in PACAP-induced SL␣ mRNA expression. Apparently, the downstream Ca 2ϩ /CaM-dependent cascades were triggered by extracellular Ca 2ϩ ([Ca 2ϩ ]e) entry via L-type voltagesensitive Ca 2ϩ channels (VSCC) and Ca 2ϩ release from IP3-sensitive intracellular Ca 2ϩ stores. In addition, the VSCC component could be activated by cAMP/PKA-and PLC/PKC-dependent mechanisms. Similar postreceptor signaling cascades were also observed for PACAP-induced SL␤ mRNA expression, except that [Ca 2ϩ ]e entry through VSCC, PKC coupling to PLC, and subsequent activation of CaMK-II were not involved. These findings, taken together, provide evidence for the first time that PACAP can induce SL␣ and SL␤ gene expression in fish model via PAC-I receptors through differential coupling to overlapping and yet distinct signaling pathways.pituitary adenylate cyclase-activating polypeptide; grass carp pituitary cells SOMATOLACTIN (SL), the latest member of the growth hormone (GH)/prolactin (PRL) family, can be identified only in fish but not in tetrapods (37). Phylogenetic analysis reveals that SL is derived from ancestral GH (16), and gene duplication in bony fish have given rise to two paralogous SL isoforms, namely SL␣ and SL␤ (47). Unlike GH and PRL, which are nonglycosylated and expressed mainly in the anterior pituitary, SL is a glycoprotein secreted by the periodic acid Schiff-positive cells located in the pars intermedia (15). Although the physiological functions of SL have not been fully characterized, its involvement in color presentation (7), body metabolism (8), osmoregulation (18), stress responses (30), and reproductive functions (31) has been proposed by various studies in fish models. Recently, it has been shown that swim bladder development can be inhibited in zebrafish by SL␤ but not SL␣ gene silencing, implying that the two SL isoforms may act differently during the process of embryo organogenesis (46). In rainbow trout, SL release can be suppressed by dopamine but stimulated by corticotropin-releasing hormone and gonadotropin-releasing hormone (GnRH; Ref. 13). In addition, SL mRNA expression can be upregulated by GnRH treatment (e.g., salmon; Ref. 26), which is in agreement with the previous reports (28) that GnRH receptors are expressed in fish pituitary cells with SL immunoreact...

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Immunohistochemical Observation of Pituitary Adenylate Cyclase–activating Polypeptide (PACAP) and Adenohypophysial Hormones in the Pituitary of a Teleost, Uranoscopus japonicus

Cited by 15 publications

References 35 publications

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

Grass carp somatolactin: I. Evidence for PACAP induction of somatolactin-α and -β gene expression via activation of pituitary PAC-I receptors

Grass carp somatolactin: II. Pharmacological study on postreceptor signaling mechanisms for PACAP-induced somatolactin-α and -β gene expression

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