Expression of alpha1D adrenergic receptor messenger RNA in oxytocin- and corticotropin-releasing hormone-synthesizing neurons in the rat paraventricular nucleus.

The paraventricular nucleus of the hypothalamus contains a number of intermingled populations of neuroendocrine cell groups involved in the hormonal stress response, including cells synthesizing corticotropin-releasing hormone and oxytocin. Ascending noradrenergic afferents to the paraventricular nucleus, acting through alpha1 adrenergic receptors, are thought to play a role in stress-induced activation of the hypothalamic-pituitary-adrenal axis. We have previously demonstrated that, of the three known alpha1 adrenergic receptor subtypes, messenger RNA for the alpha1D subtype is the most prominently expressed in the paraventricular nucleus. Thus, regulation of the expression of this receptor may be important in modulation of the stress response. It is currently unknown, however, which populations of stress-related neuroendocrine cells in the paraventricular nucleus express alpha1 receptors, or whether the excitatory influence of norepinephrine in stress is exerted directly on neurons expressing oxytocin or corticotropin-releasing hormone. Thus, in the present study, we used dual in situ hybridization, combining a digoxigenin-labeled riboprobe encoding the rat alpha1D adrenergic receptor with radiolabeled riboprobes for oxytocin or corticotropin-releasing hormone, to determine the degree to which these neurons in the paraventricular nucleus express alpha1D adrenergic receptors. In sections through the rostral and mid-level paraventricular nucleus, nearly all (>95%) oxytocin neurons also expressed alpha1D messenger RNA. In contrast, the populations of corticotropin-releasing hormone- and alpha1D-expressing cells overlapped only partially, with most alpha1D expression situated more laterally. A subset (37%) of the neurons expressing corticotropin-releasing hormone also expressed alpha1D messenger RNA, and these were found almost entirely within the region of overlap in the lateral aspect of the medial parvocellular region. These observations support a direct role for alpha1 receptors in regulation of oxytocin secretion. Expression of alpha1D messenger RNA in distinct subsets of cells synthesizing corticotropin-releasing hormone may also help to clarify contradictory and inconsistent observations in the literature regarding the role of norepinephrine in the stress response, and may account for a presumed stressor-specific role for norepinephrine in activation of the hypothalamic-pituitary-adrenal axis.     

Prostaglandins mediate lipopolysaccharide effects upon cholecystokinin and neurotensin phenotypes in neuroendocrine corticotropin-releasing hormone neurons: in situ hybridization evidence in the rat

Intraperitoneal injection of the endotoxin lipopolysaccharide produces an inflammation accompanied by immune system activation and secretion of cytokines that stimulate the hypothalamo-pituitary-adrenal (HPA) axis to release the anti-inflammatory corticosterone. Upstream in HPA axis are neuroendocrine corticotropin-releasing hormone neurons in the paraventricular nucleus whose multipeptidergic phenotype changes during inflammation: coexisting corticotropin-releasing hormone and cholecystokinin mRNAs are up-regulated whereas neurotensin mRNA expression is induced de novo. These changes may be mediated by prostaglandins released from perivascular and microglial cells in response to circulating cytokines. We examined by quantitative in situ hybridization histochemistry whether blockade of prostaglandin synthesis by indomethacin alters phenotypic expression in paraventricular nucleus neurons after lipopolysaccharide. Because indomethacin also elevated circulating corticosterone, animals were adrenalectomized and corticosterone replaced. Results showed that i.p. indomethacin administration suppressed lipopolysaccharide effects in a phenotype non-specific manner: one injection was sufficient to prevent both the increase in corticotropin-releasing hormone and cholecystokinin mRNAs expression and the induction of neurotensin mRNA expression. Therefore, neuroendocrine corticotropin-releasing hormone neurons with different peptidergic phenotypes appear to respond as a whole in the acute phase response to systemic infection.     

Corticotropin-releasing hormone messenger RNA distribution and stress-induced activation in the thalamus

Corticotropin-releasing hormone plays a critical role in mediating the stress response. Brain circuits hypothesized to mediate stress include the thalamus, which plays a pivotal role in distributing sensory information to cortical and subcortical structures. In situ hybridization revealed neurons containing corticotropin-releasing hormone messenger RNA in the posterior thalamic nuclear group and the central medial nucleus of the thalamus, which interfaces with the ventral posteromedial nucleus (parvicellular part). These regions are of interest because they process somatosensory and visceral information. In the first experiment, the effect of acute stress on thalamic corticotropin-releasing hormone messenger RNA levels was assessed. Rats restrained for 1 h and killed 1 h later were found to have increased corticotropin-releasing hormone messenger RNA in the posterior thalamic nuclear group. The time course of these changes was examined in a second experiment in which rats were killed immediately or 3 h after restraint. While no changes occurred in the thalamus immediately after restraint, 3 h after restraint, increases in corticotropin-releasing hormone messenger RNA occurred in both the posterior thalamic nuclear group and the central medial-ventral posteromedial nucleus (parvicellular part) of the thalamus. A different pattern of activation was observed in the paraventricular nucleus of the hypothalamus with increased corticotropin-releasing hormone messenger RNA immediately after restraint, but not 1 or 3 h later. In addition to the stress-induced changes, a prominent decrease in baseline thalamic corticotropin-releasing hormone messenger RNA was observed from 1000 to 1300 h.These results show that the thalamus contains corticotropin-releasing hormone messenger RNA that increases after restraint stress, indicating a role for thalamic corticotropin-releasing hormone systems in the stress response. Stress-induced changes in thalamic corticotropin-releasing hormone messenger RNA expression appears to be regulated differently than that in the paraventricular nucleus of the hypothalamus, and may be influenced by diurnal mechanisms.     

Neuronal activity and stress differentially regulate hippocampal and hypothalamic corticotropin-releasing hormone expression in the immature rat

Corticotropin-releasing hormone, a major neuromodulator of the neuroendocrine stress response, is expressed in the immature hippocampus, where it enhances glutamate receptor-mediated excitation of principal cells. Since the peptide influences hippocampal synaptic efficacy, its secretion from peptidergic interneuronal terminals may augment hippocampal-mediated functions such as learning and memory. However, whereas information regarding the regulation of corticotropin-releasing hormone's abundance in CNS regions involved with the neuroendocrine responses to stress has been forthcoming, the mechanisms regulating the peptide's levels in the hippocampus have not yet been determined. Here we tested the hypothesis that, in the immature rat hippocampus, neuronal stimulation, rather than neuroendocrine challenge, influences the peptide's expression. Messenger RNA levels of corticotropin-releasing hormone in hippocampal CA1, CA3 and the dentate gyrus, as well as in the hypothalamic paraventricular nucleus, were determined after cold, a physiological challenge that activates the hypothalamic pituitary adrenal system in immature rats, and after activation of hippocampal neurons by hyperthermia. These studies demonstrated that, while cold challenge enhanced corticotropin-releasing hormone messenger RNA levels in the hypothalamus, hippocampal expression of this neuropeptide was unchanged. Secondly, hyperthermia stimulated expression of hippocampal immediate-early genes, as well as of corticotropin-releasing hormone. Finally, the mechanism of hippocampal corticotropin-releasing hormone induction required neuronal stimulation and was abolished by barbiturate administration. Taken together, these results indicate that neuronal stimulation may regulate hippocampal corticotropin-releasing hormone expression in the immature rat, whereas the peptide's expression in the hypothalamus is influenced by neuroendocrine challenges.     

Central corticotropin-releasing hormone receptors modulate hypothalamic-pituitary-adrenocortical and sympathoadrenal activity during stress

The role of brain corticotropin-releasing hormone receptors in modulating hypothalamic-pituitary-adrenal and sympathoadrenal responses to acute immobilization stress was studied in conscious rats under central corticotropin-releasing hormone receptor blockade by intracerebroventricular injection of a peptide corticotropin-releasing hormone receptor antagonist. Blood for catecholamines, adrenocorticotropic hormone and corticosterone levels was collected through vascular catheters, and brains were removed at 3 h for in situ hybridization for tyrosine hydroxylase messenger RNA in the locus coeruleus, and corticotropin-releasing hormone and corticotropin-releasing hormone receptor messenger RNA in the hypothalamic paraventricular nucleus. Central corticotropin-releasing hormone receptor blockade reduced the early increases in plasma epinephrine and dopamine, but not norepinephrine, during stress. Immobilization stress increased tyrosine hydroxylase messenger RNA levels in the locus coeruleus by 36% in controls, but not in corticotropin-releasing hormone antagonist-injected rats. In control rats, corticotropin-releasing hormone messenger RNA and type 1 corticotropin-releasing hormone receptor messenger RNA in the paraventricular nucleus increased after stress (P<0.01), and these responses were attenuated by central corticotropin-releasing hormone receptor blockade. In contrast, central corticotropin-releasing hormone antagonist potentiated plasma adrenocorticotropic hormone responses, but slightly attenuated plasma corticosterone responses to stress. The inhibition of plasma catecholamine and locus coeruleus tyrosine hydroxylase messenger RNA responses to stress by central corticotropin-releasing hormone receptor blockade supports the notion that central corticotropin-releasing hormone regulates sympathoadrenal responses during stress. The attenuation of stress-induced corticotropin-releasing hormone and corticotropin-releasing hormone receptor messenger RNA responses by central corticotropin-releasing hormone receptor blockade suggests direct or indirect positive feedback effects of corticotropin-releasing hormone receptor ligands on corticotropin-releasing hormone expression, whereas additional mechanisms potentiate adrenocorticotropic hormone responses at the pituitary level. In addition, changes in neural activity by central corticotropin-releasing hormone are likely to modulate adrenocortical responsiveness during stress.     

The differential expression patterns of messenger RNAs encoding K-Cl cotransporters (KCC1,2) and Na-K-2Cl cotransporter (NKCC1) in the rat nervous system.

Cation-chloride cotransporters have been considered to play pivotal roles in controlling intracellular and extracellular ionic environments of neurons and hence controlling neuronal function. We investigated the total distributions of K-Cl cotransporter 1 (KCC1), KCC2 (KCC2), and Na-K-2Cl cotransporter 1 (NKCC1) messenger RNAs in the adult rat nervous system using in situ hybridization histochemistry. KCC2 messenger RNA was abundantly expressed in most neurons throughout the nervous system. However, we could not detect KCC2 messenger RNA expression in the dorsal root ganglion and mesencephalic trigeminal nucleus, where primary sensory neurons show depolarizing responses to GABA, suggesting that the absence of KCC2 is necessary for this phenomenon. Furthermore, KCC2 messenger RNA was also not detected in the dorsolateral part of the paraventricular nucleus, dorsomedial part of the suprachiasmatic nucleus, and ventromedial part of the supraoptic nucleus where vasopressin neurons exist, and in the reticular thalamic nucleus. As vasopressin neurons in the suprachiasmatic nucleus and neurons in the reticular thalamic nucleus produce their intrinsic rhythmicity, the lack of KCC2 messenger RNA expression in these regions might be involved in the genesis of rhythmicity through the control of intracellular chloride concentration. The expression levels of KCC1 and NKCC1 messenger RNAs were relatively low, however, positive neurons were observed in several regions, including the olfactory bulb, hippocampus, and in the granular layer of the cerebellum. In addition, positive signals were seen in the non-neuronal cells, such as choroid plexus epithelial cells, glial cells, and ependymal cells, suggesting that KCC1 and NKCC1 messenger RNAs were widely expressed in both neuronal and non-neuronal cells in the nervous system.These results clearly indicate a wide area- and cell-specific variation of cation chloride cotransporters, emphasizing the central role of anionic homeostasis in neuronal function and communication.     

Single administration of interleukin-1 increased corticotropin releasing hormone and corticotropin releasing hormone-receptor mRNA in the hypothalamic paraventricular nucleus which paralleled long-lasting (weeks) sensitization to emotional stressors

Single exposure to the proinflammatory cytokine interleukin-1 induces sensitization of the adrenocorticotropin hormone and corticosterone responses to stressors weeks later (hypothalamus-pituitary-adrenal sensitization). Hypothalamus-pituitary-adrenal responses are controlled by corticotropin-releasing hormone and arginine-vasopressin secreted from parvocellular corticotropin-releasing hormone neurons of the hypothalamic paraventricular nucleus and may involve autoexcitatory feedback mechanisms. Therefore, we studied the temporal relationship between resting levels of corticotropin-releasing hormone, corticotropin-releasing hormone-R1 and arginine-vasopressin receptor (V1a, V1b) mRNAs in the paraventricular nucleus and the development of hypothalamus-pituitary-adrenal sensitization to an emotional stressor (novelty). The adrenocorticotropin hormone precursor molecule proopiomelanocortin hnRNA in the pituitary gland served as an index for acute activation. Single administration of interleukin-1 induced sensitization of the hypothalamus-pituitary-adrenal to novelty from 3 to 22 days later, but not after 42 days. Single administration of interleukin-1 induced biphasic increases in corticotropin-releasing hormone and corticotropin-releasing hormone-R1 mRNAs in the paraventricular nucleus: an early peak within 24 h, followed by a delayed (>7 days) increase that peaked after 22 days. Hypothalamic V1a and V1b mRNA levels were unaffected. In contrast, in the pituitary gland, there was an early decrease in corticotropin-releasing hormone-R1 mRNA (from 10.5 to 3 h after interleukin-1) and V1b receptor mRNA (3 to 6 h), which returned to control levels from 24 h onwards. Thus, interleukin-1-induced long-lasting hypothalamus-pituitary-adrenal sensitizations associated with prolonged activation of corticotropin-releasing hormone and corticotropin-releasing hormone-R1 mRNA expression in the paraventricular nucleus, but not with changes in the expression of proopiomelanocortin hnRNA or V1b receptor or corticotropin-releasing hormone R1 mRNAs in the pituitary gland. We propose that transient exposure to immune events can induce long-lasting hypothalamus-pituitary-adrenal sensitization, which at least in part involves long-term hypothalamic adaptations that enhance central corticotropin-releasing hormone signaling.     

Subpopulations of corticotropin-releasing hormone neurosecretory cells distinguished by presence or absence of vasopressin: confirmation with multiple corticotropin-releasing hormone antisera

Parvocellular corticotropin-releasing hormone neurosecretory cells in the hypothalamic paraventricular nucleus project axons to the portal capillary plexus in the external zone of the median eminence. Immunocytochemical studies have identified two approximately equal subpopulations of these corticotropin-releasing hormone neurons in normal rats, distinguished by the presence or absence of co-existent vasopressin, and different responses to stress. However, it was recently proposed that the vasopressin deficient cells do not contain corticotropin-releasing hormone, but have been misidentified due to cross-reactivity of the corticotropin-releasing hormone antiserum to peptide histidine-isoleucineamide. It is shown here that the same set of corticotropin-releasing hormone neurons (including both vasopressin expressing and vasopressin deficient subtypes) was labeled with multiple corticotropin-releasing hormone antisera. These included two antisera that did not cross-react with peptide histidine-isoleucineamide: one against ovine corticotropin-releasing hormone, and one rat corticotropin-releasing hormone antiserum absorbed with peptide histidine-isoleucineamide. The results provide further support for the hypothesis of functionally distinct compartments of the corticotropin-releasing hormone neurosecretory system that can modulate the ratio of vasopressin to corticotropin-releasing hormone in portal blood.     

Immunocytochemical detection of corticotropin-releasing factor: multiple cross-reactions of a widely used carboxy-terminally directed corticotropin-releasing factor antiserum (code rC70) in rat hypothalamus

Forty-one-residue corticotropin-releasing factor is a physiologically significant mediator of the hypothalamic control of corticotropin secretion by the anterior pituitary gland. This releasing hormone is produced by parvicellular neurons in the hypothalamic paraventricular nucleus that project to the external zone of the median eminence. Recent immunocytochemical evidence based on work with a rabbit antiserum against rat corticotropin-releasing factor (code rC70) suggests that about half of the parvicellular corticotropin-releasing factor-containing neurons in the hypothalamic paraventricular nucleus synthesize vasopressin, another potent corticotropin secretagogue, while the rest of the cells do not. If this is indeed the case, the neurohumoral control of corticotropin release may be mediated via distinct hypothalamic effector pathways utilizing releasing hormone cocktails of varying composition. In the present study we have examined the specificity of various antisera against rat corticotropin-releasing factor in immunocytochemical staining. Male Wistar rats pretreated with colchicine were used throughout. The brain was fixed by perfusion with a Zamboni type fixative solution. Vibratome sections of the hypothalamus were immunostained with three different primary antisera (codes rC70, rCRF-3, oCRF-N) using the peroxidase-antiperoxidase or avidin-biotin complex methods. All three antisera stained cell groups previously described to be immunopositive for corticotropin-releasing factor. Most notably, however, rC70 labelled a significant number of additional cells, most readily identified in the arcuate and suprachiasmatic nuclei, as well as in the dorsolateral hypothalamic area caudal to the paraventricular nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of salt loading on vasopressin gene expression in magno- and parvocellular hypothalamic neurons: an immunocytochemical and in situ hybridization analysis

Arginine vasopressin peptide and messenger RNA expression were examined at the cellular level in the magnocellular and parvocellular neurons in the rat paraventricular nucleus after dehydration and rehydration, employing immunocytochemistry and in situ hybridization histochemistry on the same tissue sections. Most magnocellular vasopressinergic neurons of control animals expressed both vasopressin-like immunoreactivity and messenger RNA. However, neurons negative for vasopressin-like immunoreactivity but expressing messenger RNA were also detected, and their number increased during dehydration. In contrast, almost all of the parvocellular vasopressinergic neurons of dehydrated animals expressed vasopressin messenger RNA alone, with continued increase in their number after rehydration, despite return of the number of magnocellular vasopressinergic neurons to the control level. Vasopressin messenger RNA and corticotropin releasing factor-like immunoreactivity were co-localized in the same parvocellular neurons, and vasopressin-immunoreactive nerve terminals were detected in the external zone of the median eminence. These findings suggest that magno- and parvocellular vasopressinergic neurons are differentially activated during dehydration/rehydration. Osmotic stimuli activate all magnocellular vasopressinergic neurons, but the effect is not simultaneous in all of these neurons. Parvocellular vasopressinergic neurons are also activated by the stress of dehydration which effect appears to last longer than in the magnocellular system.     

Co-expression of vasopressin and androgen-binding protein in the rat hypothalamus

In previous studies we have observed the expression of androgen binding protein (ABP) in the rat hypothalamo-neurohypophysial system. With immunocytochemical double staining we found partial co-localization with oxytocin. In the present study we used antibodies to the anti-diuretic hormone arginine vasopressin (AVP) for co-localization with ABP in the rat hypothalamus. Both antigens were seen in the magnocellular paraventricular and supraoptic nuclei. Dense fiber networks with varicosities containing both AVP and ABP immunoreactivity were visible throughout the hypothalamus, the median eminence and in the posterior pituitary lobe. Double immunostaining revealed also co-existence in the parvocellular portion of the paraventricular nucleus and in the suprachiasmatic nucleus. ABP immunoreactive neurons in the preoptic region were devoid of AVP staining, AVP neurons in the bed nucleus of the stria terminalis stained only occasionally for ABP. We conclude that both the magnocellular and the parvocellular hypothalamic vasopressin systems are capable of expressing the steroid binding globulin, which is probably subject to axonal transport, along with the peptide hormone. Intrahypothalamic expression of ABP may be among the mechanisms necessary for rapid actions of steroids on hypothalamic neuroendocrine systems.     

The effects of prenatal stress on the development of hypothalamic paraventricular neurons in fetal rats.

The present experiments focused on the influence of prenatal stress on the development of neurons of the hypothalamic paraventricular nucleus in the fetal rat, including corticotropin-releasing factor-containing neurons. Prenatal stress was administered by restraining pregnant rats in a small cage for either 30 (30-min stress group) or 240 min (240-min stress group) daily for three days from embryonic day 15 to 17, and the fetal brains were taken on embryonic day 18 for later analysis. Golgi-impregnated neurons of the paraventricular nucleus in the 240-min stress group revealed that the total length of the processes was significantly shorter than in the control (unstressed) and 30-min stress groups. In addition, the 240-min stress group showed an increase in the number of apoptotic cells in the fetal paraventricular nucleus. On the other hand, Golgi-impregnated neurons of the paraventricular nucleus in the 30-min stress group had a greater degree of cell differentiation as manifested by an increase in both the number of branch points and the total length of the processes from the cell body. Furthermore, the fetal paraventricular nucleus in the 30-min stress group showed enhanced corticotropin-releasing factor messenger RNA expression, while the varicosities of corticotropin-releasing factor-containing axons at the median eminence revealed more matured morphology such as shorter intervals between the varicosities. These findings suggest the duration-dependent effects of prenatal stress on the development of fetal hypothalamic paraventricular nucleus neurons, including corticotropin-releasing factor-containing neurons: long-lasting stress causes neurotoxic changes of fetal paraventricular nucleus neurons, whereas short-lasting stress facilitates the development of these fetal brain neurons. These morphological changes induced by prenatal stress may contribute to behavioral changes of the offspring after birth.     

Stress,the neuroendocrine system and mast cells: current understanding of their role in psoriasis

Psychological stress can activate the hypothalamic–pituitary–adrenal axis and sensory nerves in the brain and skin, resulting in the release of neuroendocrine and neural mediators such as, corticotropin-releasing hormone, neuropeptides, neurotrophins and α-melanocyte-stimulating hormone. These factors can activate mast cells to release proinflammatory mediators and some of them, for example, histamine, tryptase and nerve growth factor, can stimulate sensory C-fibers. Since corticotropin-releasing hormone, sensory nerves and mast cell numbers are increased in the psoriatic lesion, a feedforward loop can exist potentiating the inflammation. Studies in rats and mice have shown that mast cells are activated during standardized stress through corticotropin-releasing hormone and sensory nerves. Therefore, the role of stress, the neuroendocrine system and mast cells in psoriasis is discussed in this article.     

Opioid synapses on vasopressin neurons in the paraventricular and supraoptic nuclei of juvenile monkeys.

Opioid peptide- as well as vasopressin-containing neurons synapse on gonadotropin releasing hormone neurons in juvenile macaques. In this study we performed double-label immunostaining for opioid and vasopressin neurons in the paraventricular and supraoptic nuclei in order to assess their interrelationships. Neuroendocrine neurons in the hypothalamus were prelabeled by microinjection of electron-dense retrograde tracer into the median eminence, and were easily identified in frontal Vibratome sections. Sections through the paraventricular and supraoptic nuclei were immunostained for vasopressin with the peroxidase-antiperoxidase technique, and for opioids using the indirect immunogold method. By light microscopy, opioid-immunoreactive inputs appeared to innervate an average of 39% of the vasopressin neurons in the paraventricular nucleus and 33% in the supraoptic nucleus, and were more prevalent anteriorly. Clusters of opioid afferents formed cup-like calices around major processes of many vasopressin neurons, especially in the paraventricular nucleus. Electron microscopy revealed that these groups of opioid axon terminals made frequent symmetrical and fewer asymmetrical synapses on both neuroendocrine and non-neuroendocrine vasopressinergic cell bodies and dendrites. Our study did not reveal vasopressin-opioid synapses in these hypothalamic nuclei, but this does not preclude the possibility of their existence elsewhere. These results indicate that opioid afferents modulate vasopressin neuronal activity in the monkey paraventricular and supraoptic nuclei. Previous results have suggested that corticotropin releasing hormone acts via vasopressinergic neurons to stimulate opioid neuronal activity and to inhibit gonadotropin releasing hormone release. Taken together, the data suggest that stressful stimuli could initiate a series of neuropeptidergic interactions which ultimately alter pulsatile gonadotropin releasing hormone secretion and thus gonadotropin secretion in primates.     

Localization of messenger RNAs encoding crustacean hyperglycemic hormone and gonad inhibiting hormone in the X-organ sinus gland complex of the lobster Homarus americanus.

The localization of messenger RNAs encoding the crustacean hyperglycemic hormone, involved in regulation of carbohydrate metabolism and the gonad inhibiting hormone, which inhibits vitellogenesis, was studied in the eyestalk of the lobster Homarus americanus using complementary RNA probes for in situ hybridization. For the detection of gonad inhibiting hormone messenger RNA, we cloned and sequenced a partial complementary DNA encoding lobster gonad inhibiting hormone and for crustacean hyperglycemic hormone messenger RNA detection an available complementary DNA was used. This approach reveals that there is a frequent but inconsistent cellular co-localization of the two neurohormones. Furthermore, our data show that male lobsters contain an equal number of neuroendocrine gonad inhibiting hormone cells as female lobsters. An additional study, involving the use of in situ hybridization in combination with immunocytochemistry, shows that the synthetic activity of the crustacean hyperglycemic hormone- and gonad inhibiting hormone-producing cells can be followed at the messenger RNA as well as the protein level. This reveals that when strong immunostaining is present, the messenger RNA staining is usually weak or absent and vice versa. In conclusion, the presence of cells, containing only gonad inhibiting hormone messenger RNA or only crustacean hyperglycemic hormone messenger RNA, indicates that lobster crustacean hyperglycemic hormone and gonad inhibiting hormone originate from two different precursors. Co-localization of the two neurohormone messenger RNAs confirms the co-localization at the peptidergic level found by immunocytochemistry and thus these findings were not due to cross-reactions between the two antisera.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential effects of cocaine and methamphetamine on neurotensin/neuromedin N and preprotachykinin messenger RNA expression in unique regions of the striatum

This study employed in situ hybridization to directly compare the effects of cocaine and methamphetamine on neurotensin/neuromedin N and preprotachykinin messenger RNAs in distinct striatal regions. Male, Sprague-Dawley rats received a single administration of 15mg/kg methamphetamine (s.c.) or 30mg/kg cocaine (i.p.) and were killed 30min or 3h later. Methamphetamine and cocaine produced significant increases in preprotachykinin messenger RNA in the striatum after 3h, but often in different subregions. Both drugs produced similar effects on preprotachykinin messenger RNA in the rostral striatum. However, methamphetamine produced significant increases in all regions of the caudal striatum, whereas cocaine-induced preprotachykinin messenger RNA expression was limited to dorsal regions of this striatal area. Methamphetamine also produced a significant increase in preprotachykinin messenger RNA in the caudal striatum after 30min, whereas cocaine had no significant effect on preprotachykinin messenger RNA at this early time-point. The pattern of changes in neurotensin/neuromedin N messenger RNA caused by methamphetamine and cocaine after 3h was even more distinct. Cocaine produced significant increases in neurotensin/neuromedin N messenger RNA in all regions of the rostral striatum, whereas methamphetamine had no effect in these areas. Furthermore, in more caudal sections, cocaine predominantly affected neurotensin/neuromedin N expression in dorsal aspects of the striatum, whereas methamphetamine significantly increased neurotensin/neuromedin N messenger RNA in all regions. There was much less effect of either drug on neuropeptide expression in the nucleus accumbens. The only significant effect was an increase in neurotensin/neuromedin N messenger RNA in the core region 3h after methamphetamine administration. These results indicate that methamphetamine and cocaine increase preprotachykinin and neurotensin/neuromedin N messenger RNAs in distinct regions of the striatum. The ability of methamphetamine and cocaine to alter neuropeptide messenger RNA expression in unique regions of the striatum may be important for the long-term effects of these drugs, such as sensitization, since the striatum is not homogeneous in its connections and function.