Colocalization of tyrosine hydroxylase and Fos in the male Syrian hamster brain following different states of arousal

In an investigation of the role that central tyrosine hydroxylase-(TH) containing neurons play in copulation in the male Syrian hamster, The induction of Fos protein was used as an index of neuronal activation. With a double immunoperoxidase technique, the activation of TH neurons was compared in hamsters from three experimental groups: (1) mated in a new cage; (2) handled controls placed in a new cage, and (3) unhandled controls. Although mating selectively induces Fos production in the medial amygdaloid nucleus (Me), more than half of the TH neurons in Me (a region outside of the classical catecholamine systems) expressed Fos equally in all of the experimental groups. In the paraventricular hypothalamic nucleus (PVN), TH neurons were activated equivalently in mated and handled control animals compared to unhandled controls. TH neurons in the neucleus of the solitary tract (NST) were also activated in handled control animals, and mating further enhanced the level of Fos immunostaining in these neurons above both groups of nonmated animals. Although not quantified, co-localization of Fos and TH was also observed in all experimental groups in the olfactory bulbs and the interfascicular nucleus, and in the horizontal limb of the diagonal band of Broca and the cerebral cortex, regions which contain TH neurons but are not part of the classically described TH cell groups. Few, if any, TH neurons in other catecholaminergic brain regions, such as the substantia nigra and locus coeruleus, produced Fos in any of the experimental groups. These results suggest that TH neurons in the PVN and NST may be activated during different states of arousal, and that nonclassical TH neurons in the amygdala produce high levels of Fos even in unstimulated animals. 1994 John Wiley & Sons, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50083/1/480250207_ftp.pd

The delta subunit of rod specific cyclic GMP phosphodiesterase, PDE δ, interacts with the Arf-like protein Arl3 in a GTP specific manner

Recently, we have shown that the δ subunit of the cGMP phosphodiesterase (PDE δ) interacts with the retinitis pigmentosa guanine regulator (RPGR). Here, using the two-hybrid system, we identify a member of the Arf-like protein family of Ras-related GTP-binding proteins, Arl3, that interacts with PDE δ. The interaction was verified by fluorescence spectroscopy and co-immunoprecipitation. Arl3 features an unusually low affinity for guanine nucleotides, with a KD of 24 nM for GDP and 48 μM for GTP. Fluorescence spectroscopy shows that PDE δ binds and specifically stabilizes the GTP-bound form of Arl3 by strongly decreasing the dissociation rate of GTP. Thus, PDE δ is an effector of Arl3 and could provide a novel nucleotide exchange mechanism by which PDE δ stabilizes Arl3 in its active GTP-bound form