Distinct substance P- and calretinin-containing projections from the supramammillary area to the hippocampus in rats; a species difference between rats and monkeys.
Our recent studies showed the co-existence of substance P and calretinin in the supramammillo-hippocampal pathway of monkeys, as well as species differences in the synaptic targets of extrinsic substance P fibers in the hippocampi of monkeys and rats. Experiments used: (1) single and multiple stereotaxic injection of wheat germ agglutinin-conjugated HRP into the hippocampus and immunostaining for substance P in the supramammillary area; (2) colocalization of substance P and calretinin in supramammillary area cells; and (3) colocalization of these two neurochemicals in retrogradely labeled supramammillary projective cells of both male and female rats. These demonstrated: (a) many calretinin- and fewer substance P-immunoreactive neurons retrogradely labeled in the ipsilateral supramammillary area; (b) approximately 74% of all substance P cells contain calretinin and 9% of the calretinin neurons co-contain substance P; and, most importantly (c) none of the retrogradely labeled supramammillary cells colocalize calretinin and substance P. These results indicate the presence of two distinct supramammillo-hippocampal projections in the rat, one that contains substance P and the other calretinin. The latter innervates the same areas as those in the monkey, and the former terminates only in the CA2 hippocampal subfield.
Borhegyi
Z
Z
Department of Functional Neuroanatomy, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
Leranth
C
C
D000818:Animals; D064032:Calbindin 2; D005260:Female; D000882:Haplorhini; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D006651:Histocytochemistry; D008297:Male; D008326:Mammillary Bodies / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D009412:Nerve Fibers / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D013045:Species Specificity; D013373:Substance P / Q000378:metabolism*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
C576512:Calb2 protein, rat; D064032:Calbindin 2; D064030:S100 Calcium Binding Protein G; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D013373:Substance P