Calcitonin gene-related peptide in the amygdaloid complex of the rat: immunohistochemical and quantitative distribution, and drug effects on calcium dependent, potassium-evoked in vitro release.
The amygdaloid complex is an area with a high concentration of calcitonin gene-related peptide. In the present paper, immunohistochemical studies revealed a dense innervation of the central nucleus originating most probably from the bed nuclei of the stria terminalis. For determination of tissue concentrations of calcitonin gene-related peptidelike immunoreactivity, the amygdaloid complex was dissected into four parts. The distribution was found to be uneven with the highest concentration (1153.3 fmol/mg protein) in the portion including the nucleus amygdaloideus centralis. High performance liquid chromatographic analysis from an extract of amygdaloid tissue showed that 97% of the calcitonin gene-related peptidelike immunoreactivity measured by radioimmunoassay is authentic rat calcitonin gene-related peptide alpha or beta. Release of calcitonin gene-related peptidelike immunoreactivity was measured in superfused slices of amygdalae pooled from three rats. High potassium (60 mM) caused a significant release of calcitonin gene-related peptidelike immunoreactivity (from 0.88% of total tissue content to 1.91%) from the amygdaloid complex in vitro, which was blocked in calcium-free buffer. Pretreatment with haloperidol or clozapine caused a significant reduction of the 60 mM potassium-evoked release, compared with a saline treated control group (control 21.0 fmol; haloperidol 2.8 fmol; clozapine 8.8 fmol) and an increase of tissue levels after haloperidol treatment by 43%. These results demonstrate that calcitonin gene-related peptide is integrated in amygdaloid functions and possibly a target for actions of neuroleptic drugs.
Haring
C
C
Department of Psychiatry, University Hospital, Innsbruck, Austria.
Humpel
C
C
Skofitsch
G
G
Krobath
J
J
Javorsky
F
F
Saria
A
A
D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003024:Clozapine / Q000494:pharmacology; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D007150:Immunohistochemistry; D011188:Potassium / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D003024:Clozapine; D006220:Haloperidol; D015740:Calcitonin Gene-Related Peptide; D011188:Potassium; D002118:Calcium