Ja. Danks et al., PARATHYROID HORMONE-RELATED PROTEIN IN TISSUES OF THE EMERGING FROG (RANA-TEMPORARIA) - IMMUNOHISTOCHEMISTRY AND IN-SITU HYBRIDIZATION, Journal of Anatomy, 190, 1997, pp. 229-238
Using antiserum to human parathyroid hormone-related protein (1-16) [P
THrP(1-16)] we have examined tissues of the common frog (Rana temporar
ia) for the presence of immunoreactive PTHrP (irPTHrP) at the stage of
emergence from water to land. irPTHrP was detected in dorsal and vent
ral stratum granulosum of the skin, in the developing ovary, striated
muscle and the choroid plexus epithelium of the brain as well as in th
e olfactory gland epithelium and olfactory lobe neurons of the brain.
In the pituitary and hypothalamus irPTHrP protein could be demonstrate
d in the median eminence, infundibular stem and principally in the neu
ral lobe and pars distalis of the pituitary with weak reaction in the
pars intermedia. In situ hybridisation of the same tissues with an oli
gonucleotide probe to chicken PTHrP 55-65 clearly showed the presence
of mRNA for PTHrP-like molecule in all the tissues containing irPTHrP.
There was a major inconsistency in the pituitary in that the highest
level of gene expression, assessed by in situ hybridisation, was found
in the pars intermedia with only very low expression in the pars dist
alis and neural lobe and undetectable levels in the infundibular stem
and median eminence. These observations suggest that tissues of the fr
og synthesise a PTHrP-like molecule but that in the pituitary the pars
intermedia cells may export the protein to cells in other regions of
the pituitary and hypothalamus.