Sequence and expression of the rat prodynorphin gene

The effect of cycloheximide on the regulation of proenkephalin and prodynorphin gene expressions induced by kainic acid in rat hippocampus

The effect of cycloheximide (CHX), a protein synthesis inhibitor, on the regulation of proenkephalin (proENK) and prodynorphin (proDYN) mRNA levels, proto-oncogenes, such as c-fos, 35-kDa fra and c-jun mRNA, and the levels of their products induced by kainic acid (KA) in rat hippocampus was studied. The proENK and proDYN mRNA levels were markedly increased 4 and 8 h after KA (10 mg/kg i.p.) administration. However, the intracellular proENK protein level was not affected by KA. The elevations of both proENK and proDYN mRNA levels induced by KA were inhibited by pre-administration of CHX (15 mg/kg i.p.). The increases of proENK and proDYN mRNA levels induced by KA were well-correlated with the increases of c-Fos, 35-kDa Fra and c-Jun protein levels. KA administration increased the hippocampal levels of c-Fos, 35-kDa Fra and c-Jun proteins with the time. The increases of c-Fos, 35-kDa Fra and c-Jun protein levels induced by KA administration were also inhibited by CHX pre-administration. KA administration markedly increased both c-fos and c-jun mRNA levels during 1 and 4 h and the increased levels of these proto-oncogene mRNA were further prolonged by the treatment with CHX. In addition, CHX alone increased both c-fos and c-jun mRNA levels although the onset times of induction were different. In electrophoretic mobility shift-assay, both AP-1 and ENKCRE-2 DNA-binding activities were increased by KA. KA-induced increases of AP-1 and ENKCRE-2 DNA-binding activities were also attenuated by CHX. In addition, KA-induced AP-1 and ENKCRE-2 DNA-binding activities were diminished by the antibodies against Fos and Jun family proteins. Furthermore, the cross-competition studies revealed that AP-1 proteins actively participated in ENKCRE-2 DNA domain. The results suggest that KA-induced proENK and proDYN mRNA expressions may require on-going synthesis of proteins, such as c-Fos, c-Jun and 35-kDa Fra, which may have a possible role in the up-regulation of proENK and proDYN gene expression through the binding with AP-1 and ENKCRE-2 DNA-binding motifs.

Chronic food restriction and streptozotocin-induced diabetes differentially alter prodynorphin mRNA levels in rat brain regions

It was previously reported that chronic food restriction and streptozotocin-induced diabetes lead to brain region-specific changes in levels of Prodyn-derived peptides. These changes parallel behavioral adaptations that are reversed by opioid antagonists. In the present study, effects of food restriction and diabetes on Prodyn gene expression were measured in rat brain regions using a quantitative solution hybridization mRNA assay. Picogram amounts of Prodyn mRNA were determined in extracts of five brain regions. The highest density of Prodyn mRNA was observed in extracts of nucleus accumbens (4.68 pg/microg total RNA), bed nucleus of the stria terminalis (4.18 pg/microg), and in caudate nucleus (3.51 pg/microg). Lower levels were observed in the lateral hypothalamus (1.87 pg/microg) and central nucleus of the amygdala (1.22 pg/microg). Food restriction and diabetes both markedly increased the levels of Prodyn mRNA in the central amygdala (163% and 93%, respectively). Levels in the lateral hypothalamus were also increased (35% and 29%, respectively), though only the food-restriction effect was statistically significant. Neither treatment altered prodynorphin mRNA levels in the caudate nucleus, nucleus accumbens or bed nucleus of the stria terminalis. These results suggest that dynorphin neurons in central amygdala and lateral hypothalamus may be involved in behavioral or physiological adaptations to sustained metabolic need.

Opioidergic and dopaminergic gene expression in the caudate-putamen and accumbens of the mutant mouse, tottering (tg/tg)

Expression of preproenkephalin, dynorphin and D2 dopamine receptor mRNAs was examined in selected regions of the forebrain of homozygous and heterozygous tottering mice, using in situ hybridization histochemistry. Homozygous tottering mice carry an autosomal recessive mutation causing them to exhibit petit mal-like epilepsy. Preproenkephalin mRNA levels were significantly higher in the lateral caudate and the core of the nucleus accumbens of homozygous tottering mice compared to wild-type controls. No differences were observed in the expression of dynorphin and D2 receptor mRNA distribution in brain regions examined in the mutant mice as compared to wild-type controls.

Enhancement of the behavioral response to apomorphine administration following repeated treatment in the 6-hydroxydopamine-lesioned rat is temporally correlated with a rise in striatal preproenkephalin-B, but not preproenkephalin-A, gene expression

Repeated dopamine receptor stimulation in the 6-hydroxydopamine (6-OHDA)-lesioned rat produces a marked enhancement in the behavioral response to a given dose of dopamine agonist. Such treatment also increases the synthesis of preproenkephalin-B (PPE-B) throughout the striatum and preproenkephalin-A (PPE-A) rostrally. To examine the relationship between these changes, 6-OHDA-lesioned rats were treated with apomorphine (5 mg/kg) twice-daily. Between 0.5 and 7 days treatment, behavior was monitored and the levels of PPE-A and PPE-B mRNA were determined by in situ hybridization. A single injection of apomorphine induced a well-known rotational response contraversive to the lesion (314 +/- 22 rotations h-1). However, with repeated injection, the response to apomorphine was markedly enhanced, being significantly higher on Days 3 (704 +/- 60 rotations h-1), 5 (1354 +/- 104 rotations h-1), and 7 (1680 +/- 117 rotations h-1). In the lesioned caudate-putamen, but not in the nucleus accumbens, PPE-B expression rose in a manner that was temporally correlated with the enhanced locomotor response to apomorphine. PPE-A expression in the lesioned striatum, significantly increased only after 7 days treatment, did not correlate with the behavioral response. In conclusion, PPE-B may contribute to the development of behavioral supersensitivity following repeated dopamine-replacement therapy in animal models of Parkinson's disease.

cDNA sequence and expression of bovine prodynorphin

Prodynorphin (ProDYN) in the anterior pituitary gland appears to be processed differently from the brain, and the ProDYN-derived peptides may function differently in the anterior pituitary than in the brain. To further investigate the roles of ProDYN-derived peptides in the anterior pituitary, we have determined the nucleotide (nt) sequence of the cDNA encoding bovine ProDYN. This is the first time a complete cDNA sequence for ProDYN has been reported. The nt and deduced amino acid (aa) sequences were compared to the known ProDYN of other species. Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) combined with Southern blot analysis demonstrated that the expression of ProDYN in both the anterior and posterior pituitary glands was much lower than that in the neural tissues of the striatum and hypothalamus.

Prodynorphin, proenkephalin and kappa opioid receptor mRNA responses to acute "binge" cocaine

Previous studies showed that preprodynorphin (ppDyn) mRNA increases in caudate-putamen while kappa opioid receptor (KOR) mRNA decreases in substantia nigra after 3 and 14 days "binge" cocaine. To further characterize opioid mRNA responses, rats were administered: saline; 1 day cocaine followed by 1 day saline; 1 day cocaine; or 2 days cocaine. ppDyn mRNA in caudate-putamen increased in both groups receiving cocaine on the final day compared to groups receiving saline. Preproenkephalin (ppEnk) mRNA in caudate-putamen increased, and KOR mRNA in substantia nigra decreased, after 2 days of cocaine. Thus ppDyn mRNA is elevated acutely by cocaine, while ppEnk and KOR mRNAs show a significant response only on the second day of "binge" cocaine.

Cellular responses to psychomotor stimulant and neuroleptic drugs are abnormal in mice lacking the D1 dopamine receptor

Stimulation of dopamine D1 receptors has profound effects on addictive behavior, movement control, and working memory. Many of these functions depend on dopaminergic systems in the striatum and D1-D2 dopamine receptor synergies have been implicated as well. We show here that deletion of the D1 dopamine receptor produces a neural phenotype in which amphetamine and cocaine, two addictive psychomotor stimulants, can no longer stimulate neurons in the striatum to express cFos or JunB or to regulate dynorphin. By contrast, haloperidol, a typical neuroleptic that acts preferentially at D2-class receptors, remains effective in inducing catalepsy and striatal Fos/Jun expression in the D1 mutants, and these behavioral and neural effects can be blocked by D2 dopamine receptor agonists. These findings demonstrate that D2 dopamine receptors can function without the enabling role of D1 receptors but that D1 dopamine receptors are essential for the control of gene expression and motor behavior by psychomotor stimulants.

Guinea pig preprodynorphin mRNA: primary structure and regional quantitation in the brain

We isolated and sequenced genomic and cDNA clones of the guinea pig preprodynorphin (ppDyn) mRNA. The sequence of ppDyn mRNA was deduced from a combination of genomic and cDNA clones: The primary structure of two coding exons was derived from a genomic clone and 5' and 3' untranslated sequences were obtained using rapid amplification of cDNA ends (RACE). The predicted mRNA of 2,350 nucleotides coincides well with the size of transcripts in Northern blot analyses of RNA from different brain regions. The deduced amino acid sequence of guinea pig ppDyn shares 70%, 68%, and 61% identity to porcine, human, and rat ppDyn, respectively. The 5' untranslated sequences of guinea pig hippocampal and adrenal ppDyn mRNA are identical; both contain sequences of exon I and, like porcine mRNA, lack an exon (exon II) present in human and rat mRNA. Quantitative solution hybridization RNase protection analysis of total RNA from selected guinea pig brain regions was performed. The nucleus accumbens was found to have the greatest abundance of ppDyn mRNA, followed by caudate putamen, hippocampus, hypothalamus, amygdala, frontal cortex, olfactory bulb, and pons/medulla.

Dynorphin and epilepsy

Studies on dynorphin involvement in epilepsy are summarised in this review. Electrophysiological, biochemical and pharmacological data support the hypothesis that dynorphin is implicated in specific types of seizures. There is clear evidence that this is true for complex partial (limbic) seizures, i.e. those characteristic of temporal lobe epilepsy, because; (1) dynorphin is highly expressed in various parts of the limbic system, and particularly in the granule cells of the hippocampus; (2) dynorphin appears to be released in the hippocampus (and in other brain areas) during complex partial seizures; (3) released dynorphin inhibits excitatory neurotransmission at multiple synapses in the hippocampus via activation of kappa opioid receptors; (4) kappa opioid receptor agonists are highly effective against limbic seizures. Data on generalised tonic-clonic seizures are less straightforward. Dynorphin release appears to occur after ECS seizures and kappa agonists exert a clear anticonvulsant effect in this model. However, more uncertain biochemical data and lack of efficacy of kappa agonists in other generalised tonic-clonic seizure models argue that the involvement of dynorphin in this seizure type may not be paramount. Finally, an involvement of dynorphin in generalised absence seizures appears unlikely on the basis of available data. This may not be surprising, given the presumed origin of absence seizures in alterations of the thalamo-cortical circuit and the low representation of dynorphin in the thalamus. In conclusion, it may be suggested that dynorphin plays a role as an endogenous anticonvulsant in complex partial seizures and in some cases of tonic-clonic seizures, but most likely not in generalised absence. This pattern of effects may coincide with the antiseizure spectrum of selective kappa agonists.

Atypical and typical neuroleptic treatments induce distinct programs of transcription factor expression in the striatum

Atypical and typical neuroleptics, when administered chronically, can bring about profound but contrasting changes in schizophrenic symptoms and motor activation and dramatically modulate brain neurochemistry. To explore the transcriptional events that might be involved in this neurochemical regulation, we used immunohistochemistry and immunoblotting to examine the expression patterns of two bZip transcription factors, c-Fos and FosB, in the striatum of rats treated acutely and chronically with neuroleptic drugs of different classes. Typical and atypical neuroleptic drugs produced contrasting regulatory effects on a FosB-like protein of ca. 36-39 kDa, the molecular weight of truncated FosB (delta FosB). Chronic treatments with two typical neuroleptics, haloperidol and metoclopramide, but not with the atypical neuroleptic clozapine, led to markedly enhanced FosB-like immunoreactivity in the caudoputamen. Further, c-Fos-like protein in the striatum, considered a marker for the induction of antipsychotic actions by neuroleptic treatments, was downregulated by chronic treatment with the two potent antipsychotic drugs tested, but not by chronic treatment with metoclopramide, which has low antipsychotic efficacy but induces extrapyramidal side effects. These results suggest that chronic treatments with neuroleptics having different effects on cognitive and motor behavior induce different long-term changes in transcription factor expression in the striatum. Nevertheless, we found that neuroleptics of both classes regulated transcription factor expression in overlapping populations of striatal neurons expressing enkephalin or DARPP-32. Contrasting patterns of transcriptional regulation in these neurons may thus contribute to the distinct neurochemical and behavioral effects that characterize neuroleptics of different classes.

Effects of BDNF and NT-4/5 on striatonigral neuropeptides or nigral GABA neurons in vivo

Supranigral infusions of the TrkB-receptor-preferring neurotrophins BDNF or NT-4/5 augment locomotor behaviours, pars compacta firing rates and striatal dopamine metabolism. However these actions of BDNF or NT-4/5 may involve other neurotransmitter systems in addition to dopamine neurons in the substantia nigra. We thus investigated the effects of 2-week supranigral infusions of BDNF or NT-4/5 on rat peptidergic striatonigral neurons and nigral GABAergic neurons. Radioimmunoassay revealed that BDNF and NT-4/5 elevated substantia nigra levels of substance P (by 46 and 57% respectively) and substance K (by 64 and 81%). In addition, BDNF elevated substance K by 59% in a nigral projection area, the superior colliculus. NT-4/5 elevated dynorphin A in the substantia nigra (by 52%) and met-enkephalin in substantia nigra and globus pallidus (by 89%). None of these neuropeptides were altered in the striatum. Consistent with these findings, supranigral infusions of BDNF elevated the mRNA for preprotachykinin A in striatal neurons. In the same animals, glutamic acid decarboxylase (GAD)67 mRNA was increased by 48% in the substantia nigra. The cross-sectional area of GAD67-positive neuronal somata in the BDNF-infused nigra was increased by 59%, and 70% of nigral GABAergic neurons had a cross-sectional area > 550 microns2, whereas 95% of the neurons in vehicle-infused animals had cross-sectional areas < 550 microns2. Thus, supranigral infusions of BDNF or NT-4/5 increase tachykinin mRNA and protein levels within striatonigral neurons and increase the size and GAD67 mRNA expression levels of nigral GABAergic neurons. These results suggest that BDNF or NT-4/5 may modify the output of the basal ganglia not only through effects on dopamine neurons but also by increasing neurotransmission in striatonigral peptidergic and nigral GABAergic pathways.

Colocalization of serotonin receptor subtypes 5-HT2A, 5-HT2C, and 5-HT6 with neuropeptides in rat striatum

There are two primary output pathways from the striatum: a projection to the globus pallidus, and projection to the substantia nigra. Certain striatally expressed neuropeptides are differentially distributed between these two pathways. Specifically, enkephalin is expressed in striatopallidal neurons, whereas substance P and dynorphin are expressed in striatonigral neurons. Several serotonin receptors are also prominently expressed in the striatum, but little is known about how they fit into the molecular neuroanatomy described above. We used double-label in situ hybridization to determine the striatal distribution of the mRNAs of the serotonin2A (5-HT2A), serotonin2C (5-HT2C), and serotonin6 (5-HT6) receptors in relation to enkephalin, substance P, and dynorphin expressing output neurons. Rat brain sections were simultaneously hybridized with an 35S riboprobe for one of the serotonin receptors and a digoxygenin labeled riboprobe for one of the neuropeptides. Sections were examined by using brightfield microscopy, and the degree of colocalization of the two mRNAs determined. All the serotonin receptors colocalized extensively with all three of the neuropeptides examined. None of the serotonin receptors showed preferential colocalization in striatopallidal (enkephalin containing), or striatonigral (substance P or dynorphin containing) cells. The 5-HT2A and 5-HT2C mRNAs displayed a differential distribution with regard to the scattered islands of strongly dynorphin mRNA positive cells, which are thought to reside in the striatal patch compartment. Within these islands, 5-HT2C mRNA expression was much higher than in surrounding areas. 5-HT2A mRNA showed the opposite pattern with decreased expression over dynorphin rich cell clusters.

PC12 cells as a model to study the effects of opioids on normal and tumoral adrenal chromaffin cells

Normal adrenal chromaffin cells produce delta opioid peptides while at the same time they have mainly kappa opioid receptors. This paper describes our date regarding the expression of the prodynorphin gene, the precursor of a family of endogenous kappa opioid ligands, in the PC12 rat pheochromocytoma cell line, and the effects of synthetic kappa opioid agonists and of Naloxone on various aspects of PC12 cell function including their secretion of catecholamines, proliferation and differentiation. This is the first part of a series of projects aimed at studying, (a) the conditions under which the prodynorphin gene is expressed in normal adrenomedullary cells, and (b) the physiological role of the endogenous kappa opioids in the physiology of the adrenal medulla.

Dopamine receptor mRNA expression patterns by opioid peptide cells in the nucleus accumbens of the rat: a double in situ hybridization study

Colocalization of proenkephalin and prodynorphin mRNAs with each other as well as with D1, D2, and D3 dopamine receptor mRNAs was analyzed in the nucleus accumbens of the rat. Distinct combinations were detected in the rostral pole, core, and shell subdivisions of the nucleus accumbens. Proenkephalin and prodynorphin mRNAs were principally localized in separate cells in the core. All detectable prodynorphin cells in the core expressed D1 mRNA but not D2 mRNA. Conversely, approximately 95% of the proenkephalin-positive cells in this region expressed D2 mRNA but not D1 mRNA. This pattern was identical to that observed in the caudate putamen. In the rostral pole and the shell, embedded in a background of this "typical" colocalization pattern, clusters of cells expressing a distinct configuration were found. In these clusters, proenkephalin-positive cells expressed both prodynorphin and D1 mRNAs, but they did not express D2 mRNA. D3 and prodynorphin mRNAs were colocalized in "limbic" striatal areas, including the ventromedial caudate putamen, the rostral pole, and the medial shell. In contrast, D3 mRNA was not detected in any proenkephalin-positive cells. Together with the prodynorphin/D1 data, this suggests that a subset of prodynorphin cells expresses both D1 and D3 mRNAs. It is concluded that 1) clusters of cells that coexpress proenkephalin, prodynorphin, and D1 mRNAs overlap extensively with previously defined cytoarchitectural cell clusters in the nucleus accumbens and 2) a subset of the prodynorphin cells in the ventromedial caudate putamen and the nucleus accumbens contains both D1 and D3 mRNAs.

Parkinsonian-like locomotor impairment in mice lacking dopamine D2 receptors

Dopaminergic neuronal pathways arise from mesencephalic nuclei and project axons to the striatum, cortex, limbic system and hypothalamus. Through these pathways dopamine affects many physiological functions, such as the control of coordinated movement and hormone secretion. Here we have studied the physiological involvement of the dopamine D2 receptors in dopaminergic transmission, using homologous recombination to generate D2-receptor-deficient mice. Absence of D2 receptors leads to animals that are akinetic and bradykinetic in behavioural tests, and which show significantly reduced spontaneous movements. This phenotype presents analogies with symptoms characteristic of Parkinson's disease. Our study shows that D2 receptors have a key role in the dopaminergic control of nervous function. These mice have therapeutic potential as a model for investigating and correcting dysfunctions of the dopaminergic system.

Early changes in prodynorphin mRNA and ir-dynorphin A levels after kindled seizures in the rat

Prodynorphin mRNA and immunoreactive dynorphin A (ir-dynorphin A) levels were measured in different brain areas at various time points after amygdala kindled seizures. In the hippocampus, striatum and hypothalamus, prodynorphin mRNA levels were not significantly changed in kindled rats (killed 1 week after the last stimulus-evoked seizure), but they were significantly increased 1 h after seizures. The relative increase was the highest in the hippocampus (approximately 3-fold). In the brainstem, midbrain and cerebral cortex no changes in prodynorphin mRNA were detected in kindled rats, 1 h or 1 week after a kindled seizure. ir-Dynorphin A levels were significantly reduced in the hippocampus and in the striatum of kindled rats, as well as 5 and 60 min after kindled seizures, but they were increased back to control levels after 120 min. In the hypothalamus, ir-dynorphin A levels were significantly increased 120 min after a kindled seizure. ir-Dynorphin A levels were also significantly reduced in the brainstem and in the frontal, parietal and temporal cortex 120 min, but not 5 or 60 min, after a kindled seizure. Taken together, these data support the hypothesis that the dynorphinergic system is activated after amygdala kindled seizures, with different kinetics in different brain areas.

Arcuate nucleus neurons that project to the hypothalamic paraventricular nucleus: neuropeptidergic identity and consequences of adrenalectomy on mRNA levels in the rat

The possible role that the hypothalamic arcuate nucleus might play in mediating the increase in paraventricular nucleus corticotropin-releasing hormone mRNA levels following adrenalectomy was investigated in two series of experiments. In the first series in situ hybridization histochemistry was used to quantify levels of eight accurate nucleus neuropeptide and neurotransmitter mRNAs in neurons that potentially relay adrenal steroid feedback to the paraventricular nucleus. In the second series of experiments, arcuate neuropeptidergic projections to the hypothalamic paraventricular nucleus were characterized using retrograde tracing in combination with in situ hybridization histochemistry. Despite an increase in paraventricular nucleus corticotropin-releasing hormone (60%) and pituitary proopiomelanocortin mRNA levels (sixfold), arcuate mRNA levels for proopiomelanocortin, neuropeptide Y, somatostatin, galanin, dynorphin, tyrosine hydroxylase, glutamate decarboxylase, and the glucocorticoid receptor were unchanged 14 days following adrenalectomy. Neuropeptidergic characterization of arcuatoparaventricular projections was achieved by injection of the retrograde tracer fluorogold into the paraventricular nucleus; retrogradely labeled neurons were characterized with polyclonal antisera against fluorogold in combination with oligonucleotide probes directed against neuropeptide Y, proopiomelanocortin, or somatostatin. Out of these three arcuate neuropeptide Y mRNA was contained in 18% of the fluorogold-positive neurons in the arcuate, proopiomelanocortin mRNA was contained in 8%, and somatostatin mRNA was contained in 6%. Overall, the results from both experiments suggest that the arcuatoparaventricular neuropeptide Y, proopiomelanocortin, and somatostatin projections are not sensitive to a chronic (14 day) lack of adrenal steroids. These projections as well as the other arcuate neurotransmitter and neuropeptide systems appear not to contribute to the persistent elevations in paraventricular nucleus corticotropin-releasing hormone mRNA levels or pituitary proopiomelanocortin mRNA levels found in 14 day adrenalectomized rats.

The expression of proenkephalin and prodynorphin genes and the induction of c-fos gene by dopaminergic drugs are not altered in the straitum of MPTP-treated mice

The expression of proenkephalin (PENK), prodynorphin (PDYN) and c-fos genes was studied in the striatum of C57B1/6 mice treated with 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP), which are used as a rodent model of Parkinson's disease (PD). Two weeks after systemic administration of MPTP (2 x 40 mg/kg, s.c. 18h apart), the lesion of the substantia nigra (SN) could be visualised by loss of the nigral tyrosine hydroxylase (TH) mRNA hybridization signal and by a 91% decrease in striatal dopamine levels. The levels of PENK and PDYN mRNAs were not significantly changed in the striatum of the lesioned mice, as compared to non-treated controls. The induction of the immediate early gene c-fos by the dopamine D2 receptor antagonist haloperidol was not altered, while the selective D1 receptor agonist SKF 38393 failed to induce c-fos in the striatum of MPTP-treated mice. These results are in contrast to the data concerning rats with the 6-hydroxydopamine (6-OHDA) lesion of the SN, which serve as another rodent model of PD. In the striata of 6-OHDA-lesioned rats, PENK gene is upregulated, PDYN gene is down-regulated and the induction of c-fos gene by D2 receptor antagonists is abolished, whereas selective D1 receptor agonists induce c-fos gene, which does not occur in non-lesioned rats. We presume that the lack of influence of the MPTP lesion in mice on the striatal gene expression was mainly caused by insufficient dopamine depletion in the striatum, which could not be increased in this model. The importance of the changes observed in 6-OHDA-lesioned rats has been discussed in the context of the mouse and primate MPTP models of PD.

Opioid precursor gene expression in the human hypothalamus

Using in situ hybridization histochemistry, we studied the distribution of neurons that express preproopiomelanocortin (pre-POMC), preprodynorphin (pre-PDYN), and preproenkephalin (pre-PENK) gene transcripts within the human hypothalamus and surrounding structures. Of the three opioid systems, pre-POMC neurons have the most restricted distribution. Pre-POMC cells are most numerous in the infundibular nucleus and retrochiasmatic area of the mediobasal hypothalamus; a few labeled cells are present within the boundaries of the ventromedial nucleus and infundibular stalk. Pre-POMC message was not found in the limited samples of structures adjacent to the hypothalamus. In contrast to neurons that express pre-POMC, neurons expressing pre-PDYN and pre-PENK are more widely represented throughout the hypothalamus and extrahypothalamic structures. However, pre-PDYN and pre-PENK cells differ from one another in distribution. Pre-PDYN message is especially abundant in neurons of the tuberal and mammillary regions, with a distinct population of labeled cells in the premammillary nucleus and dorsal posterior hypothalamus. Pre-PDYN gene expression also is found in neurons of the dorsomedial nucleus, ventromedial nucleus, caudal magnocellular portion of the paraventricular nucleus, dorsolateral supraoptic nucleus, tuberomammillary nucleus, caudal lateral hypothalamus, and retrochiasmatic area. In structures immediately adjacent to the hypothalamus, pre-PDYN neurons were observed in the caudate nucleus, putamen, cortical nucleus of the amygdala, and bed nucleus of the stria terminalis. Pre-PENK neurons occur in varying numbers in all hypothalamic nuclei except the mammillary bodies. The chiasmatic region is particularly rich in pre-PENK neurons, with the highest packing density in the intermediate nucleus [the intermediate nucleus (Braak and Braak [1987] Anat. Embryol. 176:315-330) has also been termed the sexually dimorphic nucleus of the preoptic area (SDA-POA; Swaab and Fliers [1985] Science 228:1112-1115) or the interstitial nucleus of the anterior hypothalamus 1 (Allen et al. [1989] J. Neurosci. 9:497-506)], dorsal suprachiasmatic nucleus, medial preoptic area, and rostral lateral hypothalamic area. Pre-PENK neurons are numerous in the infundibular nucleus, ventromedial nucleus, dorsomedial nucleus, caudal parvicellular portion of the paraventricular nucleus, tuberomammillary nucleus, lateral hypothalamus, and retrochiasmatic area. Only a few lightly labeled cells were found in the periphery of the supraoptic nucleus and lateral tuberal nucleus. In areas adjacent to the hypothalamus, cells that contain pre-PENK message occur in the nucleus basalis of Meynert, central nucleus of amygdala, bed nucleus of the stria terminalis, caudate nucleus, and putamen.(ABSTRACT TRUNCATED AT 400 WORDS)

Alterations in mRNA levels of D2 receptors and neuropeptides in striatonigral and striatopallidal neurons of rats with neuroleptic-induced dyskinesias

Chronic neuroleptic treatment in rat produces vacuous chewing movements (VCMs), analogous to TD in humans. We hypothesized that these hyperkinetic movements were due to alterations in striatonigral and striatopallidal GABAergic spiny II neurons. Rats were treated for 36 weeks with haloperidol decanoate and withdrawn for 28 weeks. Striatonigral and striatopallidal neurons were assessed using in situ hybridization histochemistry for mRNA levels of D1 and D2 dopamine receptors, preproenkephalin (ENK), prodynorphin (DYN), protachykinin (substance P), and glutamate decarboxylase (GAD67) in the dorsolateral and ventromedial striatum as well as the nucleus accumbens. Rats that did not develop VCMs (-VCM) had increased D2 receptor and DYN mRNA, and reduced substance P mRNA in the dorsolateral striatum. Rats with persistent VCMs (+VCM) had increased D2 receptor, ENK, and DYN mRNA in both striatal regions, and increased ENK and DYN mRNA in the nucleus accumbens, compared with controls. Relative to -VCM rats, however, +VCM rats only had increased ENK mRNA in the nucleus accumbens. Considering the overall pattern of mRNA changes, the data suggest that alterations in both the D1-mediated striatonigral and the D2-mediated striatopallidal pathways play a role in the expression of the VCM syndrome. To the extent that gene expression parallels changes in neuronal activity, this implies that the VCM syndrome is associated with increased activity in both pathways.

Distribution of preproenkephalin mRNA in the chicken and pigeon telencephalon

Bioassay and immunological studies have detected the presence of opioid peptides in the nervous system of representatives of all classes of vertebrates. The present study evaluates the expression and localization of preproenkephalin (PPE) mRNA to determine the sites of synthesis of the enkephalin peptides in the adult chicken and pigeon telencephalon using in situ hybridization histochemistry. We used a 500-base-pair chicken RNA probe corresponding to chicken PPE cDNA. In both the chicken and the pigeon telencephalon, the highest concentration of PPE mRNA-containing cells was observed in the lobus parolfactorius, paleostriatum augmentatum, nucleus accumbens, and septum. Distinct populations of labeled cells were also detected in the hyperstriatum accessorium, hippocampus, area parahippocampalis, nucleus of the diagonal band, cortex dorsolateralis, and cortex piriformis. Differences in PPE mRNA expression between chicken and pigeon were observed in several telencephalic regions. For instance, the bulbus olfactorius was heavily labeled in the pigeon, but was not labeled in the chicken, and numerous PPE mRNA-containing cells were present in the area parahippocampalis of pigeons but not of chickens. In contrast, in the hyperstriatum dorsale and hyperstriatum ventrale, numerous PPE mRNA-expressing cells were detected in the chicken but not in the pigeon. Overall, PPE mRNA-expressing cells were more numerous than enkephalin-immunoreactive cells described in previous studies. In addition, our results suggest that the general pattern of enkephalin expression in the avian telencephalon is similar to that found in other vertebrates. Finally, the results of the present study illustrate some differences in the pattern of PPE mRNA distribution between closely related species, indicating the existence of species-specific neurochemical pathways, which may influence and perhaps mediate different behaviors characteristics of these species.

Rostrocaudal subregional differences in the response of enkephalin, dynorphin and substance P synthesis in rat nucleus accumbens to dopamine depletion

Quantitative in situ hybridization histochemistry was used to examine the effects of unilateral 6-hydroxydopamine lesions of the ascending dopaminergic fibres on levels of mRNA encoding the neuropeptides enkephalin, dynorphin and substance P in subregions of the nucleus accumbens. The nucleus accumbens was divided into quadrants and changes in mRNA were measured along the rostrocaudal extent of the nucleus. Two weeks after the lesion an increase was found in enkephalin mRNA in the lesioned side compared to the non-lesioned side, whereas a decrease was observed for dynorphin and substance P mRNA. The changes in mRNA levels differed from quadrant to quadrant and were not uniformly distributed along the rostrocaudal axis. Both types of changes, i.e. increase and decrease, were much higher in rostral parts of the nucleus than in caudal parts, indicating regional differences in the effects of blockade of the dopaminergic neurotransmission. The lesion-induced increases and decreases in mRNA levels occurred in both the shell and the core subregions of the nucleus accumbens and were not specifically related to either of these areas. Factors are discussed that may contribute to the rostrocaudal gradient in the changes of enkephalin, substance P and dynorphin mRNA levels. On the basis of their afferent and efferent connections, the rostral and caudal parts of the nucleus accumbens are considered to be involved in different functions. The present results suggest that dopamine depletion may affect these functions in a differential manner.

Characterization of opioid binding sites in the neural and intermediate lobe of the rat pituitary gland by quantitative receptor autoradiography

Previous studies have suggested an involvement of enkephalins in regulation of oxytocin (OXT) and vasopressin (AVP) release, which seems to disagree with the very low affinities of Met- and Leu-enkephalin for the kappa opioid receptor. As opioid receptors in the neural lobe exclusively exist of kappa receptors, we studied the binding characteristics of larger pro-enkephalin derived peptides for opioid binding sites in the neural lobe by means of light microscopic receptor autoradiography. In addition, the pharmacological characteristics of opioid binding sites in the neural lobe were compared with those in other parts of the pituitary. In the neural as well as the intermediate lobe both high and low affinity 3H-bremazocine binding sites were present. Binding to these sites was completely displaceable by both naloxone and nor-binaltorphimine suggesting that these sites represent kappa opioid receptors. Also with regard to selectivity and affinity characteristics to other ligands, opioid binding sites in the neural and intermediate lobe were quite similar. In the anterior lobe a very low level of bremazocine binding was present, which could not be displaced by nor-binaltorphimine. Displacement studies with pro-enkephalin and pro-dynorphin derived peptides showed that both groups of peptides could bind to opioid binding sites in the neural and intermediate lobe. Especially the relatively large pro-dynorphin and pro-enkephalin derived peptides, such as dynorphin 1-17 and BAM22, appeared to be very potent ligands for these opioid binding sites and were much more potent than smaller fragments, such as dynorphin 1-8, and Met- and Leu-enkephalin. These results contradict the existence of a mismatch in the neural (and intermediate) lobe with regard to the local type of opioid peptides and receptors present.

Processing of prodynorphin by the prohormone convertase PC1 results in high molecular weight intermediate forms. Cleavage at a single arginine residue

Processing of rat prodynorphin (proDyn) by the mouse prohormone convertase PC1 was investigated. Recombinant vaccinia virus vectors were used to coexpress proDyn and PC1 in rat PC12 pheochromocytoma and mouse AtT-20 corticotroph cells. In vitro experiments were also conducted by co-incubating purified proDyn and PC1. The results demonstrate that PC1 cleaves proDyn at pairs of basic residues to yield 10 and 16 kDa high molecular weight (HMW) intermediates. Additionally, PC1 cleaves proDyn at a single arginine residue to yield an 8 kDa product and the C-peptide. This demonstrates that PC1 cleaves proDyn at single and pairs of basic residues.

Morphine-induced reciprocal alterations in G alpha s and opioid peptide mRNA levels in discrete brain regions

The mechanisms involved in the development of morphine tolerance and dependence are still unknown. Recently much attention has been directed toward the changes in post receptor events. Opiate receptors, like other hormone and neurotransmitter receptors, have been shown to mediate their effects through guanine nucleotide binding proteins (G-proteins). This, in turn, may cause alterations in intracellular events, one of which is transcription of specific genes. We investigated the changes in the levels of mRNA of proenkephalin (PPE) and prodynorphin (DYN) and the stimulatory G protein alpha subunit (G alpha s) in adult morphine tolerant rats. Chronic morphine treatment induced reciprocal alterations in the levels of opioid peptide mRNA and G alpha s mRNA in discrete brain regions. In striatum, PPE mRNA decreased by 49% (P < .01) and in hypothalamus, DYN mRNA showed a decrease of 21% (P < .01). In contrast, G alpha s mRNA increased 20% (P < .01) in striatum and 97% (P < .01), in hypothalamus. In hippocampus the changes were reversed: PPE mRNA increased (55%, P < .05) and G alpha s mRNA decreased (33%, P < .01). Frontal cortex exhibited a small decrease in PPE (11.5%, P < .05) without any change on G alpha s or DYN mRNA levels. These reciprocal alterations suggest an opposing mode of regulation of G alpha s and PPE/DYN gene expression in morphine tolerant animals.

Proteins of the Golgi apparatus. Purification to homogeneity, N-terminal sequence, and unusually large Stokes radius of the membrane-bound form of UDP-galactose:N-acetylglucosamine beta 1-4galactosyltransferase from rat liver

The Golgi marker enzyme, UDP-galactose:N-acetylglucosamine beta 1-4galactosyltransferase (beta 1-4GalT) was purified 44300-fold in its intact, membrane-bound form from rat liver membranes. The protein was isolated from detergent extracts as a high-M(r) form, having a Stokes radius approximating a globular protein of M(r) 440,000. It is comprised of a single protein component as observed on SDS/polyacrylamide gels, having an M(r) near 51,000, and does not have intermolecular disulfide cross-links. N-terminal sequencing of the enzyme demonstrated that it contains an N-terminal hydrophobic stretch deduced previously from cDNA encoding for the enzyme. Previous studies have indicated that the protein may be translated at either of two AUG sites near the 5' end of the mRNA [Russo, R. N., Shaper, N. L. & Shaper, J. H. (1990) J. Biol. Chem. 265, 3324-3331], giving rise to two polypeptides, one appended with 13 amino acids. In the work described here, evidence was only found for the sequence of the short form, missing a single methionine at the N-terminus. Mild proteolytic treatment cleaved the enzyme, giving rise to low-M(r) forms which were fully catalytically active and which, upon sequencing, were missing a 66-amino-acid stretch from the N-terminus (as compared to the mouse cDNA). Proteolytic treatment was accompanied by conversion of the form having a large Stokes radius to one approximating a globular protein with M(r) near 50,000. The N-terminal stretch appears to contribute to maintenance of the form having a large Stokes radius. This may be the result of interaction with a detergent micelle, dimerization or oligomerization, or interaction with some other large, non-protein molecule, although a detergent exchange still resulted in a form having a large Stokes radius.

Numerous candidate plasticity-related genes revealed by differential cDNA cloning

Plasticity is a property of the nervous system that allows it to modify its response to an altered input. This capacity for change suggests that there are molecular mechanisms in neurons that can couple stimuli to long-term alterations in phenotype. Neuronal excitation elicits rapid transcriptional activation of several immediate-early genes, for example c-fos, c-jun and zif268. Many immediate-early genes encode transcription factors that control expression of downstream genes whose products are believed to bring about long-term plastic changes. Here we use a highly sensitive differential complementary DNA cloning procedure to identify genes that may participate in long-term plasticity. We cloned 52 cDNAs of genes induced by the glutamate analogue kainate in the hippocampus dentate gyrus. The number of these candidate plasticity-related genes (CPGs) is estimated to be 500-1,000. One of the cloned CPGs (16C8), encoding a protease inhibitor, is induced by a stimulus producing long-term potentiation and during dentate gyrus development; a second, cpg1, is dependent on activation of the NMDA (N-methyl-D-aspartate) receptor for induction and encodes a new small, dentate-gyrus-specific protein. Seventeen of the cloned CPGs encode known proteins, including six suggesting that strong neuronal activation leads to de novo synthesis of vesicular and other synaptic components.

Endogenous opioid regulation of oxytocin secretion through pregnancy in the rat

We have investigated the influence of endogenous opioids on oxytocin secretion during pregnancy. In blood-sampled conscious rats on days 18 and 21 of pregnancy plasma oxytocin concentration, measured by radioimmunoassay, was significantly increased compared to non-pregnant or post-partum rats. On days 15, 18 and 21 of pregnancy but not in non-pregnant, early pregnant or post-partum rats, the opioid antagonist naloxone caused a significant increase in plasma oxytocin compared to vehicle injection, indicating activation of an endogenous opioid restraint over oxytocin secretion. Electrically stimulated neural lobes isolated from 16- and 21-day pregnant rats released more oxytocin than those from non-pregnant rats. However, naloxone (10(-5) M) was less effective at potentiating, and the kappa-opioid agonist U50,488 (10(-5)M) was less effective at inhibiting, stimulated release at the end of pregnancy than in non-pregnant rats suggesting desensitization of oxytocin nerve terminals to actions of endogenous opioids. Neural lobes from male rats drinking 2% saline for 4 days also showed desensitization of oxytocin nerve endings to naloxone. Neither neural lobe content of dynorphin A(1-8), an endogenous kappa-opioid, nor prodynorphin mRNA expression, measured by in situ hybridization histochemistry in the supraoptic nucleus altered during pregnancy. However, neural lobe content of Met5-enkephalin significantly decreased by day 21 of gestation suggesting enhanced release.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular alterations in the neostriatum of human cocaine addicts

Molecular changes in the neostriatum of human subjects who died with a history of cocaine abuse were revealed in discrete cell populations by means of the techniques of in situ hybridization histochemistry and in vitro receptor binding and autoradiography. Cocaine subjects had a history of repeated cocaine use and had cocaine and/or cocaine metabolites on board at the time of death. These subjects were compared to control subjects that had both a negative history and toxicology of cocaine use. Selective alterations in mRNA levels of striatal neuropeptides were detected in cocaine subjects compared to control subjects, especially for the opioid peptides. Marked reductions in the levels of enkephalin mRNA and mu opiate receptor binding were found in the caudate and putamen, concomitant with elevations in levels of dynorphin mRNA and kappa opiate receptor binding in the putamen and caudate, respectively. Dopamine uptake site binding was reduced in the caudate and putamen of cocaine subjects. The greater magnitude of changes in the dorsolateral striatum (caudate and putamen) as opposed to the ventromedial striatum (nucleus accumbens) suggests that cocaine abuse preferentially alters the biosynthetic activity of striatal systems associated with sensorimotor functioning. Additionally, an imbalance in the activity of the two major striatal output pathways in cocaine users is implicated because peptide mRNA levels were reduced in enkephalinergic striatopallidal neurons and increased in dynorphinergic striatonigral neurons. Another imbalance, that of reductions of transmitter mRNA and receptor expression associated with euphoria (enkephalin and mu opiate receptors), together with elevations in mRNAs of transmitter systems associated with dysphoria (dynorphin and kappa opiate receptors), suggests a model of dysphoria and craving in the human cocaine addict brain.

RHS2, a POU domain-containing gene, and its expression in developing and adult rat

Gene expression within the central nervous system is regulated by complex interactions of DNA-binding proteins, among which are the POU domain-containing proteins, which are distantly related to homeobox proteins. These POU domain-containing proteins have been implicated in control of transcription and replication within the central nervous system. We used degenerate primers with the PCR to isolate another POU domain-containing cDNA, RHS2, from hypothalamic RNA. Isolation of a putative full-length cDNA was accomplished by using serial dilutions of a hypothalamic cDNA library grown on solid medium. This member of the class III POU family is expressed in rats from embryonic day 11.5 into adulthood, being especially prominent in the brain. We performed double-labeling hybridization histochemistry and determined that RHS2 is coexpressed with a variety of neuropeptides in medium-sized neurons in the caudate putamen and with dynorphin in the paraventricular and supraoptic nuclei of the hypothalamus. Expression of RHS2 in the caudate putamen was increased by elimination of its nigrostriatal dopaminergic innervation.

Atypical prodynorphin gene expression in corticosteroid-producing cells of the rat adrenal gland

Prodynorphin (proDyn) gene expression was examined in the rat adrenal gland. In situ hybridization revealed a heterogenous proDyn mRNA distribution limited almost exclusively to the adrenal cortex; the inner cortical layers contained the highest amounts. In the adrenal medulla, only scattered single cells were seen. By Northern (RNA) blot analysis, adrenocortical proDyn mRNA levels were highly abundant but of smaller size than proDyn transcripts found in the brain. Low levels of the brain-size proDyn mRNA transcript were detected but restricted to the medulla. A discrepancy was suggested when comparing the high abundance of proDyn mRNA levels with the low levels of proDyn-derived peptide in the adrenal. A hypothesis of nontranslation of the shorter proDyn mRNA by adrenocortical cells was rejected because polysomal loading analysis suggests that the mRNA is translated. We propose that adrenocortical proDyn-derived peptides are not targeted for storage but are released shortly after synthesis, thus accounting for low peptide levels. We also measured proDyn mRNA levels in response to stimuli known to affect adrenocortical cells and their most important function--steroidogenesis. Adrenals from hypophysectomized rats had less proDyn mRNA by a factor of 5 than adrenals from normal sham-operated rats. Normal levels were restored by adrenocorticotrophic hormone administration, indicating a potential importance of adrenal proDyn in the hypothalamic-adrenal-pituitary axis.

Striatonigral projection neurons: a retrograde labeling study of the percentages that contain substance P or enkephalin in pigeons

Two largely separate populations of neuropeptide-containing striatonigral projection neurons have been distinguished in pigeons, one population whose neurons contain substance P (SP) and dynorphin (DYN) and a second population whose neurons contain enkephalin (ENK) (Reiner, '86a; Anderson and Reiner, '90a). In the present study, we investigated the abundance of these two types of neurons relative to all striatonigral projection neurons by combining retrograde labeling by the fluorescent dye fluorogold with immunofluorescence labeling for SP and ENK. Pigeons received large intranigral injections of fluorogold to retrogradely label the striatonigral projection neurons, and several days later they were treated with colchicine (32 hours before transcardial perfusion). Adjacent series of sections through the basal ganglia were labeled for SP and ENK using immunofluorescence techniques. The tissue was examined using fluorescence microscopy and the percentages of retrogradely labeled neurons containing either SP or ENK were quantified. We found that 85-95% of the fluorogold-labeled striatonigral neurons were SP+, whereas only 1-4% were ENK+. Thus the majority of striatonigral projection neurons in pigeons appear to contain SP, whereas a small percentage contain ENK. Only a small percentage of striatonigral neurons did not contain either. Since striatal projection neurons also contain GABA (Reiner, '86b), the present results suggest that a high percentage of striatonigral projection neurons coexpress SP, DYN and GABA, whereas a small fraction coexpress ENK and GABA. The available data are consistent with the conclusion that this is true in reptilian and mammalian species as well.

Subcellular localization, partial purification, and characterization of a dynorphin processing endopeptidase from bovine pituitary

An enzyme capable of cleaving dynorphin B-29 to dynorphin B-13 is present in bovine pituitary, with 40- to 50-fold higher specific activity in the posterior and intermediate lobes than in the anterior lobe. Subcellular fractionation of bovine neurointermediate pituitary shows that this enzyme is present in the peptide-containing secretory vesicles. The enzyme has been purified 2,800-fold from whole bovine pituitaries using ion-exchange and gel filtration chromatography. Purified dynorphin-converting enzyme has a neutral pH optimum, and is subsantially inhibited by the thiol-protease inhibitor p-chloromercuriphenylsulfonic acid, but not by serine or metalloprotease inhibitors. The purified enzyme processes dynorphin B-29 at Arg14, producing both dynorphin B-14 and dynorphin B-13 in a 5:1 ratio. No other cleavages are observed, suggesting that the activity is free from other proteases and is specific for single Arg sequences. Purified enzyme also processes dynorphin A-17 at the single Arg cleavage site, generating both dynorphin A-8 and A-9 in a 7:1 ratio. The tissue distribution, subcellular localization, and substrate specificity of this enzyme are consistent with a physiological role in the processing of dynorphin B-29 and dynorphin A-17, and possibly other peptides, at single Arg residues.

Expression of the prodynorphin gene in the developing and adult cerebral cortex of the rat: an in situ hybridization study

A population of cortical neurons contains the opioid peptide dynorphin; the laminar distribution of these neurons in the adult cerebral cortex and their patterns of development are not well known. We have utilized in situ hybridization techniques to localize prodynorphin mRNA-containing neurons. Rats aged from embryonic day (E) 15 through postnatal day (P) 90 were used. Prenatal animals did not show any labeling in the cerebral cortex. By P4, prodynorphin was expressed in a small number of cortical neurons for the first time. The autoradiographic signal was restricted to perikarya. In the frontoparietal cortex, labeled neurons first appeared in layer V and the upper part of layer VI. Subsequently, from P11 onward, the band expanded in an "inside-out" sequence to include layers IV through II. In the posterior cingulate cortex and in the insular and perirhinal cortices, prodinorphin mRNA containing-neurons were located preferentially in layer V. In all cortical areas analyzed, a progressive increase in the packing density of neurons expressing prodynorphin mRNA was observed until P14; it decreased slightly thereafter.

Regulation of c-fos and c-jun expression in the rat supraoptic nucleus

1. We have investigated induction of the nuclear proto-oncogenes c-fos and c-jun in the rat supraoptic nucleus (SON) during physiological stimulation. 2. Dehydration (0-24 hr) was associated with modest, but significant increases in both c-fos and c-jun mRNA at 8 hr and 16 hr as determined by Northern analysis of total RNA extracted from microdissected SON. Prior to 8 hr, and beyond 24 hr, no consistent changes in c-fos and c-jun mRNA were found. Levels of c-fos and c-jun mRNA in the hippocampus were not altered over 24 hr of dehydration. 3. Acute stimulation with hypertonic saline (1.5 M, i.p.) resulted in a marked increase in SON c-fos mRNA at 1 hr (6-fold) and 2 hr (3.5-fold). Small increases in SON c-jun mRNA were observed at these time points. Treatment with a similar volume of 0.9% saline did not elevate SON c-fos and c-jun mRNA levels. 4. Analysis of transcriptional activity with a nuclear run-on assay showed that activation of transcription appears to mediate the induction of c-fos and c-jun mRNA following acute hypertonic saline treatment. During dehydration transcriptional activation is apparent for c-jun but is not well defined for c-fos. 5. The results are discussed with reference to the hypothesis that products of c-fos and c-jun may mediate adaptive changes in hypothalamic gene expression.

Extensive co-occurrence of substance P and dynorphin in striatal projection neurons: an evolutionarily conserved feature of basal ganglia organization

A number of different neuroactive substances have been found in striatal projection neurons and in fibers and terminals in their target areas, including substance P (SP), enkephalin (ENK), and dynorphin (DYN). In a preliminary report on birds and reptiles, we have suggested that SP and DYN are to a large extent found in the same striatal projection neurons and that ENK is found in a separate population of striatal projection neurons. In the present study, we have examined this issue in more detail in pigeons and turtles. Further, we have also explored this issue in rats to determine whether this is a phylogenetically conserved feature of basal ganglia organization. Simultaneous immunofluorescence double-labeling procedures were employed to explore the colocalization of SP and DYN, SP and ENK, and ENK and DYN in striatal neurons and in striatal, nigral, and pallidal fibers in pigeons, turtles, and rats. To guard against possible cross-reactivity of DYN and ENK antisera with each others' antigens, separate double-label studies were carried out with several different antisera that were specific for DYN peptides (e.g., dynorphin A 1-17, dynorphin B, leumorphin) or ENK peptides (leucine-enkephalin, metenkephalin-arg6-gly7-leu8, methionine-enkephalin-arg6-phe7). The results showed that SP and DYN co-occur extensively in specific populations of striatal projection neurons, whereas ENK typically is present in different populations of striatal projection neurons. In pigeons, 95-99% of all striatal neurons containing DYN were found to contain SP and vice versa. In contrast, only 1-3% of the SP+ striatal neurons and no DYN neurons contained ENK. Similarly, in turtles, greater than 75% of the SP+ neurons were DYN+ and vice versa, whereas ENK was observed in fewer than 5% of the SP+ neurons and 2% of the DYN+ neurons. Finally, in rats, more than 70% of the SP+ neurons contained DYN and vice versa, but ENK was found in only 5% of the SP+ neurons and in none of the DYN+ perikarya. Fiber double-labeling in the striatum and its target areas (the pallidum and substantia nigra) was also consonant with these observations in pigeons, turtles, and rats. These results, in conjunction with studies in cats by M.-J. Besson, A.M. Graybiel, and B. Quinn (1986; Soc Neurosci. Abs. 12:876) strongly indicate that the co-occurrence of SP and DYN in large numbers of striatonigral and striatopallidal projection neurons in a phylogenetically widespread, and therefore evolutionarily conserved, feature of basal ganglia organization.(ABSTRACT TRUNCATED AT 400 WORDS)

Peptides and transmitter enzymes in hypothalamic magnocellular neurons after administration of hyperosmotic stimuli: comparison between messenger RNA and peptide/protein levels

In situ hybridization histochemistry and indirect immunofluorescence histochemistry were used to study changes in the expression of vasopressin (VP), oxytocin (OXY), tyrosine hydroxylase (TH), galanin (GAL), dynorphin (DYN) and cholecystokinin (CCK) in hypothalamic magnocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of rats. After prolonged administration of 2% sodium chloride as drinking water (salt-loading), the treatment increased the levels of VP, OXY, TH, GAL, DYN and CCK mRNA in the PVN and SON. The increase in CCK mRNA was, however, proportionally higher in the PVN than in the SON. Within cell bodies of the PVN and SON of salt-loaded rats, a depletion of VP- and OXY-like immunoreactivity (LI) and an increase in TH-LI were seen. In salt-loaded/colchicine-treated rats, a marked decrease in GAL- and DYN-LI, but no specific changes in CCK-LI were observed. Within nerve fibers of the posterior pituitary of salt-loaded rats, a marked depletion of VP-, GAL- and DYN-LI was found. Less pronounced depletion was observed in OXY- and CCK-LI, and no specific changes in TH-LI were seen. The results show that high plasma osmolality induces increased mRNA levels for VP, OXY, TH, GAL, DYN and CCK, presumably indicating increased synthesis, an increased export from cell somata of VP, OXY, GAL and DYN, and a decrease in levels of these peptides in the posterior pituitary, suggesting increased release. The catecholamine-synthesizing enzyme TH, however, which has a cytoplasmic localization and is not released from nerve endings, remains high in the cell bodies and nerve endings during this state of increased activity.

Regulated expression of proenkephalin A during ontogenic development of mesenchymal derivative tissues

Proenkephalin A (PEA), a neuropeptide-encoding gene, is widely expressed in the nervous and endocrine systems. Recently, we demonstrated that in addition to its abundance in fetal brain tissue; PEA is markedly expressed in nondifferentiated mesodermal cells of developing fetuses. To evaluate the implication of these findings for the normal development of tissues of mesodermal origin, we examined the expression of PEA in rat mesenchymal tissues during pre- and postnatal development. Using in situ hybridization analysis combined with RNA blots and a Met-enkephalin-specific radioimmunoassay, we showed that (i) PEA mRNA levels in embryonic and newborn mesenchymal derivative tissues were as high as in the developing brain, (ii) PEA mRNA concentrations in these tissues dropped to undetectable levels shortly after birth, and (iii) this mRNA was translated and processed differentially among different mesenchymal tissues, yielding a tissue-specific pattern of PEA-derived peptides. Our results demonstrate multilevel regulation of PEA gene expression during ontogenic development of mesenchymal derivative tissues. The transient expression and the correlation between PEA mRNA and tissue maturation support the notion that peptides encoded by PEA play a significant role in normal development of these tissues. These findings provide a framework for examination of the mechanisms and roles of PEA gene expression during mesenchymal ontogeny.

Postnatal development of preproenkephalin mRNA containing neurons in the rat lower brainstem

Postnatal developmental changes of preproenkephalin (PPE) gene expression in rat brainstem neurons were studied by in situ hybridization histochemistry. On the basis of PPE mRNA expression, brainstem neurons were categorized into three types: 1) type I neurons were characterized by constant or increasing expression of PPE mRNA during postnatal development; 2) type II neurons started to express PPE mRNA several days after birth and continued to do so thereafter; and 3) type III neurons showed transient expression of PPE mRNA or stopped expressing the mRNA during early postnatal development. Type I PPE neurons were observed in diverse brainstem structures including the mesencephalic and pontine central gray matter, various reticular and raphe nuclei, the ventral tegmental area of Tsai, the interpeduncular nucleus, the nucleus of the brachium of the inferior colliculus, the ventral and dorsal tegmental nuclei of Gudden, the sphenoid nucleus, the laterodorsal tegmental nucleus, Barrington's nucleus, the parabrachial region, the lateral lemniscus and its related nuclei, the trapezoid nucleus, the rostral and ventromedial periolivary nuclei, the mesencephalic trigeminal and principal sensory trigeminal nuclei, the locus coeruleus, the subcoeruleus nucleus, the medial and spinal vestibular nuclei, the dorsal and ventral cochlear nuclei, the medial and lateral cerebellar nuclei, the Roller nucleus, and the intermedius nucleus of the medulla. Type II PPE neurons were found in the superior colliculus, the inferior colliculus, the central part of the dorsal tegmental nucleus, and as Golgi neurons in the granular layer of the cerebellum. Type III PPE neurons were located in the substantia nigra, the red nucleus, the superior olive, the motor trigeminal nucleus, the facial nucleus, the inferior olive, the dorsal motor nucleus of the vagus, and the hypoglossal nucleus. Such region-specific expression of the PPE gene during postnatal ontogeny suggests that rat brainstem PPE neurons may be involved in a variety of developmental events, such as cell proliferation, differentiation, and migration.

Optimization of non-radioactive in situ hybridization: image analysis of varying pretreatment, hybridization and probe labelling conditions

Using detection of proopiomelanocortin (POMC) mRNA in rat pituitary as a model, varying conditions of tissue pretreatment, hybridization and probe labelling have been tested. Results were evaluated both by visual assessment and by image analysis of coded specimens. Good correlations between visual gradation, optical densities and cell area percentages were obtained. However, determinations of optical densities (or pixel values) provided most detailed information. The data obtained emphasize the interdependence of fixation and permeabilization conditions and clearly show that the stronger the primary fixation, the more efficient the permeabilization by proteinase K must be. The hybridization temperature is also of importance and temperatures between 40-45 degrees C produced the best signal to noise ratio. The POMC-directed 24-mer probe had a theoretical melting point (Tm) of 49.4 degrees C (in the absence of formamide) and four individual experimental determinations of Tm produced a mean value of 48.9 degrees C. Detection of the biotinylated probe was best accomplished with monoclonal antibiotin antibodies and the alkaline phosphatase-anti-alkaline phosphatase (APAAP) system. Short washes at high-stringency (0.1 x SSC, 45 degrees C) produced an optimal signal to noise ratio. Inclusion of 50% formamide in the hybridization buffer produced an enhanced signal to noise ratio, in spite of a higher background staining. The probe employed for most studies was a synthetic 24-mer oligodeoxynucleotide, complementary to the MSH[4-11]-coding region of POMC mRNA. It was labelled with biotinylated dUTP and unlabelled dCTP using terminal transferase. Chromatographical analyses revealed the labelled probe to be heterogeneous in tail length.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulated expression of proenkephalin A during ontogenic development of mesenchymal derivative tissues

Proenkephalin A (PEA), a neuropeptide-encoding gene, is widely expressed in the nervous and endocrine systems. Recently, we demonstrated that in addition to its abundance in fetal brain tissue; PEA is markedly expressed in nondifferentiated mesodermal cells of developing fetuses. To evaluate the implication of these findings for the normal development of tissues of mesodermal origin, we examined the expression of PEA in rat mesenchymal tissues during pre- and postnatal development. Using in situ hybridization analysis combined with RNA blots and a Met-enkephalin-specific radioimmunoassay, we showed that (i) PEA mRNA levels in embryonic and newborn mesenchymal derivative tissues were as high as in the developing brain, (ii) PEA mRNA concentrations in these tissues dropped to undetectable levels shortly after birth, and (iii) this mRNA was translated and processed differentially among different mesenchymal tissues, yielding a tissue-specific pattern of PEA-derived peptides. Our results demonstrate multilevel regulation of PEA gene expression during ontogenic development of mesenchymal derivative tissues. The transient expression and the correlation between PEA mRNA and tissue maturation support the notion that peptides encoded by PEA play a significant role in normal development of these tissues. These findings provide a framework for examination of the mechanisms and roles of PEA gene expression during mesenchymal ontogeny.