Nitric Oxide as an Efferent Modulator of Circadian Pacemaker Neurones in the Eye of the Marine Mollusc Bulla gouldiana~!2008-04-11~!2008-06-27~!2008-08-26~!

Abstract

An antiserum against the nitric oxide (NO) synthetase labelled varicosities surrounding circadian pacemaker cells ("basal retinal neurons", BRNs) in the eye of the marine mollusc Bulla gouldiana. These profiles appear to arise from extrinsic neurons with axons entering the eye via the optic nerve and are distinct from FMRFamide containing profiles, which represent the only efferent optic fibres in Bulla. In intact, dark-adapted eyes, the NO-donor SNAP (S-nitroso-N-acetylpenicillamine) had no obvious effect on BRN activity recorded from the optic nerve. However, the light response of these circadian pacemaker neurones was reversibly enhanced by 8-bromo-cGMP, a tissue permeable analogue of cyclic guanosine monophosphate, and reduced by L-NAME (N -nitro-L-arginine methyl ester), a specific but irreversible inhibitor of NO synthesis. Furthermore, isolated BRNs in primary cell culture responded to the NO-donor SNAP with an elevated intracellular calcium concentration as measured by fluorescent calcium imaging using fura-2. This effect was blocked in the presence of the calcium chelator ethylene glycol tetra acetic acid (EGTA), and mimicked by application of the phosphodiesterase blocker isobutylmethylxanthine (IBMX). We propose that NO released from neurons entering the eyes, modulates the light responsiveness of the circadian pacemaker cells in Bulla by activating cGMP-gated calcium channels.

Cellular, biochemical, and molecular characterization of nitric oxide synthase expressed in the nervous system of the prosobranch Stramonita haemastoma (Gastropoda, Neogastropoda)

“…Based on their morphology and distribution these varicosities resemble the basket-like synapses described in gland cells of the snail Helix pomatia (Serfozo et al, 2008), in salivary glands and cerebral ganglia of Aplysia (Moroz, 2006), and in the buccal ganglia of Tritonia diomedea (Beck et al, 2000). Interestingly, similar varicosities immunostained for NOS in circadian pacemaker cells of the eye in the nudibranch Bulla gouldiana (Bullmann and Stevenson, 2008). Further immunohistochemical observations are required to ascertain whether NADPHd staining is related to NOS in these varicosities.…”

Nitric Oxide Synthase in the Central Nervous System and Peripheral Organs of Stramonita haemastoma: Protein Distribution and Gene Expression in Response to Thermal Stress

“…To date, there is only sparse evidence of NOS enzymes in visual systems of mollusks. NADPHd staining was found in the optic nerve of Aplysia [ 35 ] and NOS enzymes were localized in the retina of Loligo [ 36 ] and Sepia [ 37 ] and in the eye neuropile and the optic nerve of Bulla gouldiana [ 38 ]. Immunohistochemical results in S. haemastoma are conflicting with those reported for B. gouldiana whose retinal neurons were not labeled for NOS.…”

Nitric oxide affects short-term olfactory memory in the antennal lobe ofManduca Sexta

“…NO could very likely be an important modulator in this process, especially given the expression of NOS in the olfactory receptor neurons in M. sexta. NO could affect pacemaker cells in the antennae, AL and optic lobes directly, similar to the basal retinal neurons in the mollusk (Bullmann and Stevenson, 2008), or be a downstream result. Given the dramatic physiological effects of NO in AL neurons, NO could act as a 'priming' agent that adjusts olfactory and optical circuitry to enable nocturnal behaviors.…”