Fig. 5.

Co-expression of secretagogin with classical Ca²⁺-binding proteins in select brainstem nuclei of the rat. a–a₁’’ Complementary distribution of calretinin and secretagogin in the commissural part of the solitary nucleus and the dorsal nucleus of vagus (white arrowheads indicate secretagogin⁺/calretinin⁻ neurons, black arrowhead points to a secretagogin⁺/calretinin⁺ neuron). b–b₁’ Secretagogin⁺ neurons typically remained calretinin immunonegative (white arrowheads) in the spinal tract nucleus of the trigeminus, with exceptional co-expression only (black arrowhead). b₂ Single- and co-expression ratios of secretagogin and calretinin in the spinal tract nucleus of the trigeminus. 100% percentage refers to all labelled cells detected for secretagogin and/or calretinin immunoreactivity. Secretagogin⁺/calretinin⁺ neurons: 2.8 ± 3.2%, secretagogin⁺/calretinin⁻ neurons 51.2 ± 6.1%, secretagogin⁻/calretinin⁺ neurons 47.5 ± 5.4% (as of average ± s.e.m.). c–c₁’’’ Calretinin⁺ neurons in the dorsolateral part of the solitary tract nucleus can either remain immunonegative for secretagogin (white arrowheads) or co-express it (black arrowheads) Grey arrowhead points to a CR⁻/Scgn⁻/PV⁺ neuron. c₂ Single- and co-expression ratios of secretagogin and calretinin in the dorsolateral part of the solitary tract nucleus. 100% percentage refers to all labelled cells detected for secretagogin and/or calretinin immunoreactivity. Secretagogin⁺/calretinin⁺ neurons: 36.1 ± 2.3%, secretagogin⁺/calretinin⁻ neurons 16.9 ± 3.5%, secretagogin⁻/calretinin⁺ neurons 43.7 ± 2.1% (as of average ± s.e.m.). d Secretagogin⁺ neurons (white arrowheads) in the A1 field did not co-express parvalbumin (black arrowheads point to secretagogin⁻/parvalbumin⁺ somata). e–e₁’’ Secretagogin⁺ neurons typically co-expressed calbindin in the spinal tract nucleus of the trigeminus (black arrowheads). White arrowheads point to calbindin⁺/secretagogin⁻ somata, grey arrowhead to a secretagogin⁺/calbindin⁻ soma. e₂ Single- and co-expression ratios of secretagogin and calbindin in the spinal tract nucleus of the trigeminus. 100% percentage refers to all labelled cells detected for secretagogin and/or calbindin immunoreactivity. Secretagogin⁺/calbindin⁺ neurons: 19.1 ± 8.0%, secretagogin⁺/calbindin⁻ neurons 30.7 ± 11.3%, secretagogin⁻/calbindin⁺ neurons 50.2 ± 7.2% (as of average ± s.e.m.). f–f₁’’ Secretagogin⁺ neurons showed a complementary distribution to calretinin⁺ neurons in the lateral parabrachial nucleus (white arrowheads point to secretagogin⁺/calretinin⁻ somata, black arrowheads point to secretagogin⁻/calretinin⁺ somata). g Secretagogin⁺ neurons remain immunonegative for calbindin in the parabrachial nucleus. CB calbindin, CR calretinin, NTS solitary tract nucleus, NTSc commissural part of the solitary tract nucleus, Scgn secretagogin, PV parvalbumin, X dorsal nucleus of vagus, XII hypoglossal nucleus. Scale bars 150 µm (a, b, c, e), 70 µm (g), 40 µm (d, f), 10 µm (a₁’’, b₁’, c₁, e₁’’, f₁’’)