Human SCGN ELISA Matched Antibody Pair

Background: Secretagogin (Scgn), a member of the EF-hand calcium-binding protein (CaBP) superfamily, has recently been found in subsets of developing and adult neurons. Here, we have analyzed the expression of Scgn in dorsal root ganglia (DRGs) and trigeminal ganglia (TGs), and in spinal cord of mouse at the mRNA and protein levels, and in comparison to the well-known CaBPs, calbindin D-28k, parvalbumin and calretinin. Rat DRGs, TGs and spinal cord, as well as human DRGs and spinal cord were used to reveal phylogenetic variations. Results: We found Scgn mRNA expressed in mouse and human DRGs and in mouse ventral spinal cord. Our immunohistochemical data showed a complementary distribution of Scgn and the three CaBPs in mouse DRG neurons and spinal cord. Scgn was expressed in similar to 7% of all mouse DRG neuron profiles, mainly small ones and almost exclusively co-localized with calcitonin gene-related peptide (CGRP). This co-localization was also seen in human, but not in rat DRGs. Scgn could be detected in the mouse sciatic nerve and accumulated proximal to its constriction. In mouse spinal cord, Scgn-positive neuronal cell bodies and fibers were found in gray matter, especially in the dorsal horn, with particularly high concentrations of fibers in the superficial laminae, as well as in cell bodies in inner lamina II and in some other laminae. A dense Scgn-positive fiber network and some small cell bodies were also found in the superficial dorsal horn of humans. In the ventral horn, a small number of neurons were Scgn-positive in mouse but not rat, confirming mRNA distribution. Both in mouse and rat, a subset of TG neurons contained Scgn. Dorsal rhizotomy strongly reduced Scgn fiber staining in the dorsal horn. Peripheral axotomy did not clearly affect Scgn expression in DRGs, dorsal horn or ventral horn neurons in mouse. Conclusions: Scgn is a CaBP expressed in a subpopulation of nociceptive DRG neurons and their processes in the dorsal horn of mouse, human and rat, the former two co-expressing CGRP, as well as in dorsal horn neurons in all three species. Functional implications of these findings include the cellular refinement of sensory information, in particular during the processing of pain.

Psychostimulant use is an ever-increasing socioeconomic burden, including a dramatic rise during pregnancy. Nevertheless, brain-wide effects of psychostimulant exposure are incompletely understood. Here, we performed Fos-CreER(T2)-based activity mapping, correlated for pregnant mouse dams and their fetuses with amphetamine, nicotine, and caffeine applied acutely during midgestation. While light-sheet microscopy-assisted intact tissue imaging revealed drug- and age-specific neuronal activation, the indusium griseum (IG) appeared indiscriminately affected. By using GAD67(gfp/+) mice we subdivided the IG into a dorsolateral domain populated by gamma-aminobutyric acidergic interneurons and a ventromedial segment containing glutamatergic neurons, many showing drug-induced activation and sequentially expressing Pou3f3/Brn1 and secretagogin (Scgn) during differentiation. We then combined Patch-seq and circuit mapping to show that the ventromedial IG is a quasi-continuum of glutamatergic neurons (IG-Vglut1(+)) reminiscent of dentate granule cells in both rodents and humans, whose dendrites emanate perpendicularly toward while their axons course parallel with the superior longitudinal fissure. IG-Vglut1(+) neurons receive VGLUT1(+) and VGLUT2(+) excitatory afferents that topologically segregate along their somatodendritic axis. In turn, their efferents terminate in the olfactory bulb, thus being integral to a multisynaptic circuit that could feed information antiparallel to the olfactory-cortical pathway. In IG-Vglut1(+) neurons, prenatal psychostimulant exposure delayed the onset of Scgn expression. Genetic ablation of Scgn was then found to sensitize adult mice toward methamphetamine-induced epilepsy. Overall, our study identifies brain-wide targets of the most common psychostimulants, among which Scgn(+)/Vglut1(+) neurons of the IG link limbic and olfactory circuits.