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Distribution and cellular localization of preproenkephalin mRNA in the ovine brain and pituitary
S G Matthews1, R P Heavens, D J Sirinathsinghji
1Department of Behavioural Physiology, AFRC Institute of Animal Physiology and Genetics Research, Cambridge Research Station, Babraham, U.K.
Abstract:
In this study in situ hybridization histochemistry was used to determine the regional and cellular localization of preproenkephalin (PPE) mRNA in the sheep brain and pituitary. Coronal brain sections were hybridized with an 35S-labelled synthetic 45-mer deoxyribonucleotide probe complementary to a portion of the bovine PPE gene. The specificity of the probe was confirmed by Northern blot analysis. The highest density of labelled cell bodies was found in the nucleus accumbens, caudate-putamen, olfactory tubercle, the central nucleus of the amygdala, the paraventricular nucleus of the hypothalamus, the suprachiasmatic nucleus and in the gigantocellular division of the medullary reticular formation. Labelled cells were also found in the olfactory bulb, prefrontal cortex, piriform cortex and cerebral cortex and in the vicinity of the locus coeruleus, parabrachial nucleus and the nucleus of the solitary tract. In the pituitary a dense PPE mRNA signal was observed in the intermediate lobe; cells in the anterior or neural lobe did not express PPE mRNA. The widespread distribution of cells containing PPE mRNA transcripts within the ovine brain agrees with a similar distribution in the rat. The data suggest that PPE neurons may be involved in diverse physiological functions including the processing of sensory and nociceptive information and in the regulation of endocrine and motor responses.
Insights
Preproenkephalin (PPE) mRNA is widely distributed in sheep brain regions, including the nucleus accumbens and hypothalamus. This suggests diverse roles for PPE neurons in sensory processing, pain, and motor and endocrine regulation.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Preproenkephalin (PPE) is a precursor to endogenous opioids involved in pain and reward pathways.
- Understanding the distribution of PPE mRNA provides insights into neuronal function and regulation.
Purpose of the Study:
- To determine the regional and cellular localization of preproenkephalin (PPE) mRNA in the sheep brain and pituitary.
- To investigate the potential physiological roles of PPE-expressing neurons.
Main Methods:
- In situ hybridization histochemistry was employed to detect PPE mRNA.
- A 35S-labelled synthetic deoxyribonucleotide probe complementary to the bovine PPE gene was used.
- Northern blot analysis confirmed probe specificity.
Main Results:
- High densities of PPE mRNA were observed in the nucleus accumbens, caudate-putamen, olfactory tubercle, amygdala, hypothalamus, and medullary reticular formation.
- PPE mRNA was also detected in the olfactory bulb, cortex, and near the locus coeruleus.
- A dense PPE mRNA signal was present in the intermediate lobe of the pituitary, but not in the anterior or neural lobes.
Conclusions:
- The widespread distribution of PPE mRNA in the ovine brain is consistent with findings in rats.
- PPE neurons are likely involved in processing sensory and nociceptive information.
- These neurons may also play roles in regulating endocrine and motor responses.