Ric-8B interacts with G alpha olf and G gamma 13 and co-localizes with G alpha olf, G beta 1 and G gamma 13 in the cilia of olfactory sensory neurons.

Olfactory sensory neurons are able to detect odorants with high sensitivity and specificity. We have demonstrated that Ric-8B, a guanine nucleotide exchange factor (GEF), interacts with Galphaolf and enhances odorant receptor signaling. Here we show that Ric-8B also interacts with Ggamma13, a divergent member of the Ggamma subunit family which has been implicated in taste signal transduction, and is abundantly expressed in the cilia of olfactory sensory neurons. We show that Gbeta1 is the predominant Gbeta subunit expressed in the olfactory sensory neurons. Ric-8B and Gbeta1, like Galphaolf and Ggamma13, are enriched in the cilia of olfactory sensory neurons. We also show that Ric-8B interacts with Galphaolf in a nucleotide dependent manner, consistent with the role as a GEF. Our results constitute the first example of a GEF protein that interacts with two different olfactory G protein subunits and further implicate Ric-8B as a regulator of odorant signal transduction.

Efferent connections of the nucleus of the lateral olfactory tract in the rat.

The efferent connections of the nucleus of the lateral olfactory tract (LOT) were examined in the rat with the Phaseolus vulgaris leucoagglutinin (PHA-L) technique. Our observations reveal that layers II and III of LOT have largely segregated outputs. Layer II projects chiefly ipsilaterally to the olfactory bulb and anterior olfactory nucleus, bilaterally to the anterior piriform cortex, dwarf cell cap regions of the olfactory tubercle and lateral shell of the accumbens, and contralaterally to the lateral part of the interstitial nucleus of the posterior limb of the anterior commissure. Layer III sends strong bilateral projections to the rostral basolateral amygdaloid complex, which are topographically organized, and provides bilateral inputs to the core of the accumbens, caudate-putamen, and agranular insular cortex (dorsal and posterior divisions). Layer II projects also to itself and to layers I and II of the contralateral LOT, whereas layer III projects to itself, to ipsilateral layer II, and to contralateral layer III of LOT. In double retrograde labeling experiments using Fluorogold and cholera toxin subunit b tracers, LOT neurons from layers II and III were found to provide collateral projections to homonymous structures on both sides of the brain. Unlike other parts of the olfactory amygdala, LOT neither projects directly to the extended amygdala nor to the hypothalamus. Thus, LOT seemingly influences nonpheromonal olfactory-guided behaviors, especially feeding, by acting on the olfactory bulb and on ventral striatal and basolateral amygdaloid districts that are tightly linked to lateral prefrontal cortical operations.

Preliminary identification and quantification of the age-pigment lipofuscin in the brain of Farfantepenaeus paulensis (Crustacea: Decapoda).

A preliminary study was done on the age-pigment lipofuscin content in the brains of captive Farfantepenaeus paulensis juveniles (5 months old) and wild adults (estimated age of 12-15 months). Random samples of 6 individuals were obtained from each group (juvenile and adult) for histological analysis. Serial sections (6 microns) of the brains were mounted without staining and observed in an epifluorescent microscope. The fluorescent images of the five most central sections of the olfactory lobe cell mass (OLCM) of each individual were digitized for image analysis. The lipofuscin granule mean diameter was similar in both groups (p > 0.05), however the lipofuscin area fraction (percentage of the OLCM occupied by pigment granules) was significantly higher (p < 0.05) in the adult shrimp. The detection of lipofuscin granules in 5 month old F. paulensis indicates that lipofuscin deposition probably takes place even earlier in the juvenile phase. Our results suggested that the amount of granules in the F. paulensis OLCM is related to age, but further studies are necessary to evaluate the relationship between lipofuscin content and the age of captive F. paulensis.

Comparative dopamine-acetylcholine interactions in the ventral and dorsal striatum of rabbit and rat brain.

The dopamine (DA)-acetylcholine (ACh) interactions were investigated in dorsal (nucleus caudate, NC) and ventral (olfactory tubercle, OT) striatal regions, of rats and rabbits. Both regions receive a dense dopaminergic innervation and have high ACh concentrations. Brain slices of NC and OT from both animal species were prelabeled with [3H]choline and superfused. In rat and rabbit OT and NC, higher ACh release per pulse was elicited by lower than higher stimulation frequencies; in addition, rabbit tissues released a greater fraction of tissue [3H]transmitter than rat tissues. Blockade of D2 DA-receptors with sulpiride (1 microM), did not modify ACh release in OT and NC of rats and rabbits; suggesting that the lower ACh release observed in rat tissues is not due to an inhibitory dopaminergic tone on cholinergic neurons. Apomorphine (APO), a D2 DA-receptor agonist, inhibited in a concentration-dependent manner the evoked release of ACh from rat and rabbit NC (maximal inhibition = 90%). In rabbit OT, maximal inhibition induced by APO was 49 +/- 2% and in the rat OT, it was 23 +/- 1%. Sulpiride antagonized APO-induced inhibition of ACh release from rat and rabbit NC; however, it failed to prevent APO-induced inhibition in rat OT, and in the rabbit OT reduced it from 47% to 20 +/- 5%. These results indicate differences in the wiring of DA and cholinergic neurons and terminals in dorsal and ventral striatal structures, as well as between rat and rabbit tissues. Cholinergic ventral striatal structures may not receive a direct DA input, and afferent cholinergic nerve terminals (rather than interneurons) predominate in the ventral striatum.