R Nagabhushanam

In vivo stimulation of ovarian development in the red swamp crayfish, Procambarus clarkii (Girard), by 5-hydroxytryptamine

Summary The possibility that biogenic amines affect ovarian development in the red swamp crayfish, Procambarus clarkii, was investigated. Females were administered 15 μg/g body weight (bw) of norepinephrine, dopamine, 5-hydroxytryptamine (5-HT) or octopamine on days 1, 5 and 10 and were sacrificed on day 15. Crayfish given 5-HT showed significant increases in ovarian index (30.5%) and oocyte size (34.0%) over the concurrent controls, while norepinephrine, dopamine and octopamine did not significantly affect either the ovarian index or oocyte size. Significantly more labeling by 14C-leucine of ovarian proteins was found in ovaries of crayfish that were injected with 5-HT in vivo, but when ovarian lobes from crayfish that had not been injected with 5-HT were incubated in vitro with 5-HT added to the incubation medium, no significant change in the level of incorporation of 14C-leucine into ovarian proteins occurred. The 5-HT receptor blocker LY53857 (25 μg/g bw) retarded ovarian development. The 5-HT release...

Hormonally-regulated functions in crustaceans as biomarkers of environmental pollution

The effects of organic and inorganic contaminants on functions regulated by hormones in crustaceans are being investigated with increasing frequency because several of these phenomena show promise of being useful biomarkers of environmental contamination. Heavy metals and organic compounds have been found in studies with crustaceans to negatively affect hormonally-regulated functions, specifically reproduction, molting, blood glucose level, and pigmentary effectors. Neurotransmitters, including 5-hydroxytryptamine and dopamine, have been identified as being involved in stimulating or inhibiting release of specific crustacean neurohormones such as the pigment-dispersing and pigment-concentrating ones involved in color changes. The effects of pollutants on at least some of these hormonally-regulated processes appear due at least in part to impacting release of a neurohormone, possibly by affecting release of the neurotransmitter that normally stimulates release of that particular neurohormone.

In vitro inhibition by dopamine of 5-hydroxytryptamine-stimulated ovarian maturation in the red swamp crayfish,Procambarus clarkii

Dopamine inhibits 5-hydroxytryptamine-stimulated maturation of the ovaries of the red swamp crayfish,Procambarus clarkii, in vitro just as it does in vivo. This in vitro inhibition appears to be due to inhibition of release of the gonad-stimulating hormone from the brain and thoracic ganglia. However, it is possible that in vivo dopamine also triggers release of the gonad-inhibiting hormone.

Biomaterials from aquatic and terrestrial organisms

Use of Plants for Management of Alzheimer s Disease Antiviral Activity of Sulfated Polysaccharides of Marine Red Algae Anti-Inflammatory and Antiallergic Properties of Triterpenoids from Plants Antioxidant Compounds Extracted from Several Plant Materials Antimicrobial Activity of Terpenes Isolated from African Plants Antimalarial and Antifungal Alkaloids from Plants Anticancer Compounds from Higher Plants Biologically Active Natural Products from Marine Fungi Antioxidant Metabolites from Marine Derived Fungi Antiangiogenic Compounds from Marine Invertebrates Biologically Active Terpenoids from Sponges Bioactive Polyacetylenic Compounds from Marine Sponges Bioactive Natual Products from Nudibranchs Barnacle Underwater Adhesive: Complexity from Multi-Functionality in a Multi-Protein Complex Secondary Metabolites of Biological Significance from Echinoderms

Cadmium chloride induced hyperglycemia in the red swamp crayfish, Procambarus clarkii: Possible role of crustacean hyperglycemic hormone

Exposure to 5 ppm cadmium chloride for up to 72-hr produces hyperglycemia in intact Procambarus clarkii, but not in eyestalkless individuals. Extracts of eyestalks, regardless of whether the eyestalks are from cadmium exposed crayfish or crayfish kept in clean water, produce a greater hyperglycemia in eyestalkless crayfish kept in clean water than in cadmium exposed eyestalkless crayfish. This difference in effectiveness of the extracts may represent a decreased responsiveness of cadmium exposed crayfish to the crustacean hyperglycemic hormone. These results support the hypothesis that cadmium induced hyperglycemia is mediated at least in part by the crustacean hyperglycemic hormone that is produced in the eyestalk.

Evidence for opioid involvement in the regulation of ovarian maturation of the fiddler crab, Uca pugilator

Abstract The potential involvement of an endogenous opioid system in the regulation of ovarian development in the fiddler crab, Uca pugilator, was investigated in vivo. Injection of the opioid, methionine enkephalin, into female crabs significantly slowed ovarian maturation in a dose-dependent manner. In contrast, injection of the opioid antagonist, naloxone, produced dose-dependent ovarian maturation. These results provide the first evidence that an opioid system is involved in the control of reproduction in a crustacean. It is hypothesized that the opioid (a) stimulates release of the gonad-inhibiting hormone, (b) inhibits release of the gonad-stimulating hormone or (c) does both (a) and (b).

An In Vitro Study of the Inhibitory Action of Methionine Enkephalin on Ovarian Maturation in the Red Swamp Crayfish, Procambarus clarkii

Abstract The possible involvement of an endogenous opioid system in the regulation of ovarian development in the red swamp crayfish, Procambarus clarkii, was investigated in vitro. Ovarian explants exposed to the opioid methionine (Met) enkephalin and thoracic ganglia showed reduced development in a dose-dependent manner as compared with explants incubated with thoracic ganglia alone. These thoracic ganglia secrete a gonad-stimulating hormone (GSH) as shown by the fact that explants incubated with thoracic ganglia alone showed more development than did explants incubated with muscle alone. On the other hand, the opioid antagonist naloxone produced dose-dependent enhanced development of explants incubated with thoracic ganglia. The fact that Met-enkephalin and naloxone are effective with thoracic ganglia in vitro strongly suggests that a functional endogenous opioid system is present in these ganglia and modulates release of GSH.

In Vivo Effects of Dopamine and Dopaminergic Antagonists on Testicular Maturation in the Red Swamp Crayfish, Procambarus clarkii

In vivo, dopamine (DA) inhibits testicular maturation in the red swamp crayfish, Procambarus clarkii. Crayfish given DA injections had a smaller testicular index, smaller testicular lobes, fewer mature sperm, and less-well-developed androgenic glands than did the control crayfish given physiological saline. Males administered 5-hydroxytryptamine (5-HT) or a DA receptor blocker, spiperone or pimozide, showed enhanced testicular maturation and more highly developed androgenic glands than did the control crayfish. When equimolar amounts of 5-HT and DA were co-injected, the actions of DA and 5-HT were found to be antagonistic. These results can be explained by assuming not only that 5-HT triggers release of the gonad-stimulating hormone (GSH) but that DA (a) triggers release of the gonad-inhibiting hormone (GIH), (b) inhibits GSH release, or

DOPAMINERGIC INHIBITION OF 5-HYDROXYTRYPTAMINE-STIMULATED TESTICULAR MATURATION IN THE FIDDLER CRAB, UCA PUGILATOR

The in vivo effects of dopamine (DA), a dopaminergic antagonist (spiperone), and a dopaminergic agonist (ADTN) on maturation of the testes in the fiddler crab, Uca pugilator, were determined. DA inhibited testicular maturation dose-dependently. ADTN also inhibited maturation of the testes whereas spiperone induced testicular maturation. These results provide the first evidence for dopaminergic inhibition of testicular maturation in a crustacean. This DA-induced inhibition may have been due to: (a) inhibition of release of the gonad-stimulating hormone, (b) stimulation of release of the gonad-inhibiting hormone or (c) both (a) and (b).

In vivo assessment of opioid agonists and antagonists on ovarian maturation in the red swamp crayfish, Procambarus chrkii

The possible involvement of an endogenous opioid system in the regulation of ovarian development in the red swamp crayfish, Procambarus clarkii, was investigated in vivo. Injections of the opioid, methionine (Met) enkephalin, into females significantly slowed ovarian maturation in a dose-dependent manner. In contrast, injection of the general opioid antagonist, naloxone, produced dose-dependent ovarian maturation. Furthermore, the highly selective delta opioid agonist, DADLE, also inhibited ovarian maturation, whereas a highly selective delta receptor antagonist, ICI-174,864, stimulated ovarian maturation. In view of these results and the fact that Met-enkephalin is a relatively selective delta receptor agonist, we hypothesize that in the crayfish the inhibitory effect of Met-enkephalin involves this type of binding site. Furthermore, it is hypothesized that the inhibitory action of these opioids is due to either (a) stimulation of release of the gonad-inhibiting hormone, (b) inhibition of release of the gonad-stimulating hormone or (c) both (a) and (b).