Biomedical subjects

M K Raizada

Publications and source records attributed to M K Raizada.

At least 145 records · Page 8Linked to original sources

PubMed1987

Ontogeny of insulin receptors in the rat hemochorial placenta.

Binding of 125I-insulin to rat placental membranes was time and protein concentration dependent, reversible, and specific. Unlabeled porcine insulin competed for 125I-insulin binding with an IC50 of 65 nM, while IGF-I was much less potent with an IC50 of 2.12 mM. Specific binding of 125I-insulin decreased during the second half of gestation from Days 11 to 19. Scatchard analysis of the binding data for membranes prepared from Gestation Days 11 and 19 yielded typical curvilinear plots which showed a marked decrease in the number of binding sites in late gestation placenta. Beginning on Day 14, insulin binding was characterized with isolated labyrinth and basal zone portions of the hemochorial placenta. There was no evidence for differences in Kd values or the number of binding sites in these two functionally distinct portions of the rat placenta. Crosslinking of 125I-insulin followed by SDS-PAGE showed a single protein with a molecular weight of 130,000 from placental tissues on Gestation Days 11 and 19 and confirmed a gestational decrease in the number of insulin receptors. In solubilized, lectin-purified preparations from placenta and liver membranes, insulin stimulated the phosphorylation of a Mr 95,000 protein. 32P-incorporation into this 95,000 protein was stimulated fivefold by insulin in Day 11 placenta receptor, whereas no detectable 32P-incorporation was found in Day 19 placenta. Thus, while the alpha- and beta-subunits of insulin receptors in mid and late gestation placenta have molecular weights which are similar to receptors in maternal liver, data indicate the presence of a functional difference in insulin-stimulated kinase activities.

Animals↗

PubMed1987

Distinct angiotensin II receptor in primary cultures of glial cells from rat brain.

Angiotensin II (Ang-II) has profound effects on the brain. Receptors for Ang-II have been demonstrated on neurons, but no relationship between glial cells and Ang-II has been established. Glial cells (from the hypothalamus and brain stem of 1-day-old rat brains) in primary culture have been used to demonstrate the presence of specific Ang-II receptors. Binding of 125I-Ang-II to glial cultures was rapid, reversible, saturable, and specific for Ang-II. The rank order of potency of 125I-Ang-II binding was as follows: Ang-II = [sarcosine1,Ala8]Ang-II greater than [sarcosine1,Ile8]Ang-II much greater than Ang-III greater than Ang-I. Scatchard analysis revealed a homogeneous population of high-affinity (Kd = 1.1 nM) binding sites with a Bmax of 110 fmol/mg of protein. Light-microscopic autoradiography of 125I-Ang-II binding supported the kinetic data, documenting specific Ang-II receptors on the glial cells. Ang-II stimulated a dose-dependent hydrolysis of phosphatidylinositols in glial cells, an effect mediated by Ang-II receptors. However, Ang-II failed to influence [3H]norepinephrine uptake, and catecholamines failed to regulate Ang-II receptors, effects that occur in neurons. These observations demonstrate the presence of specific Ang-II receptors on the glial cells in primary cultures derived from normotensive rat brain. The receptors are kinetically similar to, but functionally distinct from, the neuronal Ang-II receptors.

Angiotensin II↗

PubMed1987

Protein kinase C agonists increase the expression of angiotensin II receptors in neuronal cultures.

Previous studies have shown that norepinephrine is important in the regulation of central angiotensin II receptors, an effect mediated by alpha 1-adrenergic receptors. Because alpha 1-adrenergic stimulation leads to inositol phospholipid hydrolysis and activation of protein kinase C, we have examined a possible role of this enzyme in the regulation of central angiotensin II (Ang II) receptors. In the present study, we have examined the effects of protein kinase C activators, phorbol esters, on the expression of Ang II receptors in neuronal cultures prepared from 1-day-old rat brains. The active phorbol ester phorbol-12-myristate-13-acetate (TPA) caused time- and concentration-dependent increases in the specific binding of [125I]Ang II to its receptors in neuronal cultures of normotensive and spontaneously hypertensive rat brains. The stimulatory effect of TPA on Ang II receptors was apparent within 15 min and reached a maximum between 1 and 2 h. Ang II specific binding had returned to control levels by 24 h. Various phorbol esters increased [125I]Ang II binding in accordance with their order of potency in stimulating protein kinase C activity. Saturation and Scatchard analysis revealed that the phorbol ester-induced increase in [125I]Ang II binding was due to an increase in the number of Ang II receptors. These observations indicate that activation of protein kinase C results in an increased expression of Ang II receptors in neuronal cultures from both normotensive and spontaneously hypertensive rat brains. The results suggest a possible role of phosphorylation in Ang II receptor expression in neuronal cultures.

Angiotensin II↗

PubMed1987

Norepinephrine metabolism in neuronal cultures is increased by angiotensin II.

In this study we have examined the actions of angiotensin II (ANG II) on catecholamine metabolism in neuronal brain cell cultures prepared from the hypothalamus and brain stem. Neuronal cultures prepared from the brains of 1-day-old Sprague-Dawley rats exhibit specific neuronal uptake mechanisms for both norepinephrine (NE) and dopamine (DA), and also monoamine oxidase (MAO) and catechol O-methyltransferase (COMT) activity. Separate neuronal uptake sites for NE and DA were identified by using specific neuronal uptake inhibitors for each amine. In previous studies, we determined that ANG II (10 nM-1 microM) stimulates increased neuronal [3H]NE uptake by acting at specific receptors. We have confirmed these results here and in addition have shown that ANG II (1 nM-10 microM, 10-120 min) has no significant effects on neuronal [3H]DA uptake. These results suggest that the actions of ANG II are restricted to the NE transporter in neuronal cultures. It is possible that ANG II stimulates the intraneuronal metabolism of at least part of the NE that is taken up, because the peptide stimulates MAO activity, an effect mediated by specific ANG II receptors. ANG II had no effect on COMT activity in neuronal cultures. Therefore, the use of neuronal cultures of hypothalamus and brain stem we have determined that ANG II can specifically alter NE metabolism in these areas, while apparently not altering DA metabolism.

Angiotensin II↗

PubMed1987

Norepinephrine regulation of alpha-1 receptors and alpha-1-stimulated phosphoinositide hydrolysis in primary neuronal cultures.

Alpha-1 receptor density and alpha-1 receptor-stimulated phosphoinositide hydrolysis in neuronal primary cultures are regulated by exposure of the cells to the alpha-1 agonist norepinephrine (NE). Pretreatment of neuronal cultures with 10 microM NE caused a time- and concentration-dependent decrease in NE-stimulated accumulation of [3H]inositol phosphates. The maximal NE-stimulated inositide hydrolysis was decreased by approximately 80% after 2 hr of pretreatment with NE, and this loss of responsiveness was reversible over a period of 12 hr. NE pretreatment of neuronal cultures did not affect the muscarinic receptor stimulation of inositide hydrolysis. Neither the number of alpha-1 receptor recognition sites, assessed by measuring the specific binding of DL-[125I]-alpha-(3-iodohydroxyphenyl)-ethyl-aminomethyl tetralone ([125I]HEAT), nor the Ki for NE inhibition of [125I]HEAT binding were changed appreciably after treating neurons with NE for 2 hr. A time- and concentration-dependent decrease in alpha-1 receptor recognition sites occurred with longer periods of NE pretreatment. The maximal loss of 50 to 60% [125I]HEAT binding sites was seen after 14 hr of pretreatment with NE. The number of [125I]HEAT binding sites returned to control levels within 24 hr in parallel with the recovery of alpha-1-stimulated inositide hydrolysis after being down-regulated by a 24-hr exposure to NE. Cycloheximide (3.5 microM) blocked both the recovery of alpha-1 receptors and the recovery of alpha-1-stimulated inositide hydrolysis after 24 hr of NE pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Insulin inhibits specific norepinephrine uptake in neuronal cultures from rat brain.

Neuronal cells in primary culture have been demonstrated to possess specific insulin receptors (Boyd et al., J. Biol. Chem., 260 (1985) 15880-15884). Incubation of these cultures with insulin causes a dose-dependent inhibition of maprotiline-sensitive [3H]norepinephrine uptake. Maximum inhibition of 95% of maprotiline-sensitive norepinephrine uptake was observed at an insulin concentration of 167 nM with an ED50 of 30 nM. Competition-inhibition and Scatchard analysis of the insulin binding data suggested that maprotiline competed for high-affinity insulin receptors. These observations suggest that both insulin and maprotiline specifically inhibit neuronal norepinephrine uptake possibly involving insulin receptors.

Animals↗

PubMed1986

Sodium increases angiotensin II receptors in neuronal cultures from brains of normotensive and hypertensive rats.

Neuronal cultures from one-day-old brains of Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats were used to determine the effect of sodium ions on angiotensin II (Ang II) receptors in order to understand the mechanism of action of sodium at the cellular level. Incubation with sodium chloride of neuronal cultures from WKY rats caused a rapid and dose-dependent increase in the specific binding of 125I-Ang II to its receptors. A 260% increase in the binding was observed with 150 mM NaCl. Neuronal cultures from SH rat brains showed a similar sodium-stimulated increase in Ang II binding; however this increase was 150% greater than that observed in neuronal cultures from WKY rat brain. Kinetic studies of the effects of sodium ions on both WKY and SH neuronal cultures showed an increase in the dissociation of 125I-Ang II from its receptors in the presence of sodium ions. In addition, Scatchard analysis revealed that the increase in binding caused by sodium was due to an increase in the number of Ang II receptors. These observations indicate that sodium ions increase the number of Ang II specific receptors in intact neuronal cells and that this stimulation was more pronounced in neuronal cells from SH rat brains compared with WKY controls.

Angiotensin II↗

PubMed1986

Effects of AF64A on [3H]acetylcholine synthesis in neuron-enriched primary brain cell cultures.

[3H]Acetylcholine (ACh) synthesis was measured in primary neuronal cultures from neonatal rat brains. Neuronal [3H]ACh synthesis was blocked by hemicholinium-3 and depended on the age of the cultures, increasing for ca. 10 days, and eventually declining. The irreversible inhibitor AF64A (10 or 30 microM) inhibited [3H]ACh synthesis from [3H]choline at concentrations (10 or 30 microM) with affecting choline acetyltransferase activity. Nine-day-old cultures recovered 90% of their [3H]ACh synthesis within 7 days after AF64A, while 13-day-old cultures never recovered. These results suggest that the turnover of neuronal choline transporters is age-related.

Acetylcholine↗

PubMed1986

Insulin is released from rat brain neuronal cells in culture.

Depolarization of neuronal cells in primary culture from the rat brain by potassium ions in the presence of calcium or by veratridine caused a greater than three-fold stimulation of release of immunoreactive insulin. HPLC of the released insulin immunoreactivity from the neuronal cultures comigrated with the two rat insulins. The depolarization-induced release of insulin was inhibited by cycloheximide and was specific for neuronal cultures since potassium ions failed to cause the release in comparably prepared astrocytic glial cells from the rat brain. Prelabelling of neuronal cultures with [3H]leucine followed by depolarization resulted in the release of radioactivity that immunoprecipitated with insulin antibody. The release of [3H]insulin was biphasic. These observations suggest that neuronal cells from the brain have the capacity to synthesize insulin that could be released under depolarization conditions.

Animals↗

PubMed1986

Alpha 1-adrenergic receptor-mediated downregulation of angiotensin II receptors in neuronal cultures.

Previous evidence has suggested that brain catecholamine levels are important in the regulation of central angiotensin II receptors. In the present study, the effects of norepinephrine and 3,4-dihydroxyphenylethylamine (dopamine) on angiotensin II receptor regulation in neuronal cultures from rat hypothalamus and brainstem have been examined. Both catecholamines elicit significant decreases in [125I]angiotensin II-specific binding to neuronal cultures prepared from normotensive rats, effects that are dose dependent and that are maximal within 4-8 h of preincubation. Saturation and Scatchard analyses revealed that the norepinephrine-induced decrease in the binding is due to a decrease in the number of angiotensin II receptors in neuronal cultures, with little effect on the receptor affinity. Norepinephrine has no significant actions on [125I]angiotensin II binding in cultures prepared from spontaneously hypertensive rats. The downregulation of angiotensin II receptors by norepinephrine or dopamine is blocked by alpha 1-adrenergic and not by other adrenergic antagonists, a result suggesting that this effect is initiated at the cell surface involving alpha 1-adrenergic receptors. This is further supported by our data indicating a parallel downregulation of specific alpha 1-adrenergic receptors elicited by norepinephrine. In summary, these results show that norepinephrine and dopamine are able to alter the regulation of neuronal angiotensin II receptors by acting at alpha 1-adrenergic receptors, which is a novel finding.

Angiotensin II↗

PubMed1986

Alpha 1-adrenergic receptors in neuronal cultures from rat brain: increased expression in the spontaneously hypertensive rat.

Neuronal cells in primary culture from 1-day-old brains of normotensive, Wistar-Kyoto strain (WKY) and spontaneously hypertensive (SH) rats have been utilized to study the expression of alpha 1-adrenergic receptors. Binding of a selective alpha 1 antagonist, [125I]2-[beta-(4-hydroxy-3-iodophenyl)-ethylaminomethyl]-tetralone ([125I]HEAT) to neuronal membranes prepared from primary brain cultures of WKY and SH rats was 75-80% specific, rapid, and time-dependent although the binding was 1.5-2 times higher in neuronal membranes from SH rat brain cultures. Kinetic analysis of the association and dissociation data demonstrated no significant differences between rat strains. Competition-inhibition experiments provided IC50 values for various antagonists and agonists in the following order: prazosin less than phentolamine less than yohimbine less than phenylephrine less than norepinephrine less than propranolol, suggesting that [125I]HEAT bound selectively to alpha 1-adrenergic receptors. Scatchard analysis of the binding data provided straight lines for both strains of rats, indicating the presence of a homogeneous population of binding sites. It also showed that the increase in the binding in neuronal cells from SH rat brains over those from normotensive WKY controls was a result of an increase in the number of alpha 1-adrenergic receptors. Incubation of neuronal cultures from both strains of rats with phenylephrine, an alpha 1-adrenergic agonist, caused a time- and dose-dependent decrease in the binding of [125I]HEAT. This decrease was due to a decrease in the number of alpha 1-adrenergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Characteristics of the beta-adrenoreceptor from neuronal and glial cells in primary cultures of rat brain.

The cellular characteristics of the beta-adrenoreceptor in glial and neuronal cells from the newborn rat brain were determined by (-)-[125I]iodocyanopindolol binding. In membranes from both cell types, the binding was saturable and from competition assays the potency series of (-)-isoproterenol greater than (-)-epinephrine = (-)-norepinephrine greater than (+)-isoproterenol was observed. 5'-Guanylyl-imidodiphosphate reduced the affinity of (-)-isoproterenol for the beta-adrenoreceptor from glial cells but had no effect on agonist affinity in neuronal cells. Chronic treatment of both cell types with (-)-isoproterenol reduced the receptor content and the capacity of the agonist to increase the cellular cyclic AMP content. However, the receptor recovery after chronic agonist treatment was faster in glial cells (72 h) than neuronal cells (120 h) and was blocked by cycloheximide. Treatment of both types with the irreversible beta-blocker bromoacetylalprenololmentane (2 microM) reduced the receptor content by 78% but no receptor recovery was observed for 120 h after the initial receptor loss. The data indicated that the majority of beta-adrenoreceptors in both cell types are the beta-1 subtype, but show some differences in receptor-agonist interactions. Furthermore, these CNS cells may be useful models for regulatory studies on the beta-adrenoreceptor.

Adrenergic beta-Agonists↗

PubMed1986

Angiotensin II stimulates norepinephrine uptake in hypothalamus-brain stem neuronal cultures.

In this study we have characterized the uptake of [3H]norepinephrine (NE) into neuronal co-cultures of rat hypothalamus and brain stem and have examined the effects of angiotensin II (ANG II) on this uptake. Neuronal co-cultures prepared from the brains of 1-day-old Sprague-Dawley (SD) or Wistar-Kyoto (WKY) rats exhibited sodium-dependent and sodium-independent portions of the total [3H]NE uptake. The sodium-dependent uptake was abolished by blockers such as maprotiline, desmethylimipramine, and xylamine (0.1-100 microM) and is presumably neuronal uptake. The sodium-independent uptake was unaffected by these drugs and is presumably non-neuronal, since nonneuronal co-cultures from SD rats exhibited no significant sodium-dependent or blocker-sensitive uptake. In SD or WKY neuronal co-cultures, ANG II (0.1 nM-10 microM) caused increased [3H]NE uptake during short-term incubations (1-5 min). This stimulatory effect of ANG II was on neuronal NE uptake. Furthermore, it was inhibited by preincubation with saralasin (1-10 microM). Construction of saturation curves and kinetic analyses revealed that ANG II caused an increase in the maximal velocity of uptake of neuronal [3H]NE, but the affinity of the transporter for NE was not altered. With longer-term incubations (15-30 min), ANG II caused a reduction in neuronal [3H]NE uptake. This effect was also blocked by saralasin. However, reliable kinetic analysis was not possible with the longer-term incubations, and it is likely that the inhibitory action of the peptide represents a stimulation of NE release. Therefore, using neuronal co-cultures, we have identified a previously unseen stimulatory action of ANG II on neuronal [3H]NE uptake, which precedes the already documented inhibitory actions.

Angiotensin II↗

PubMed1986

Decreased alpha 1-adrenergic receptor-mediated inositide hydrolysis in neurons from hypertensive rat brain.

The expression of alpha 1-adrenergic receptors and norepinephrine (NE)-stimulated hydrolysis of inositol phospholipid has been studied in neuronal cultures from the brains of normotensive (Wistar-Kyoto, WKY) and spontaneously hypertensive (SH) rats. Binding of 125I-2-[beta-(4-hydroxyphenyl)-ethyl-aminomethyl] tetralone (HEAT) to neuronal membranes was 68-85% specific and was rapid. Competition-inhibition experiments with various agonists and antagonists suggested that 125I-HEAT bound selectively to alpha 1-adrenergic receptors. Specific binding of 125I-HEAT to neuronal membranes from SH rat brain cultures was 30-45% higher compared with binding in WKY normotensive controls. This increase was attributed to an increase in the number of alpha 1-adrenergic receptors on SH rat brain neurons. Incubation of neuronal cultures of rat brain from both strains with NE resulted in a concentration-dependent stimulation of release of inositol phosphates, although neurons from SH rat brains were 40% less responsive compared with WKY controls. The decrease in responsiveness of SH rat brain neurons to NE, even though the alpha 1-adrenergic receptors are increased, does not appear to be due to a general defect in membrane receptors and postreceptor signal transduction mechanisms. This is because neither the number of muscarinic-cholinergic receptors nor the carbachol-stimulated release of inositol phosphates is different in neuronal cultures from the brains of SH rats compared with neuronal cultures from the brains of WKY rats. These observations suggest that the increased expression of alpha 1-adrenergic receptors does not parallel the receptor-mediated inositol phosphate hydrolysis in neuronal cultures from SH rat brain.

Adrenergic alpha-Antagonists↗

PubMed1986

Development of brain insulin receptors: structural and functional studies of insulin receptors from whole brain and primary cell cultures.

We studied the structural and functional characteristics of insulin receptors from rat brain and liver from late gestation through adulthood as well as from cultured neuronal and glial cells from neonatal rats. Specific insulin binding was present on membrane preparations from brain and liver at all stages of development studied, with maximal binding in neonates greater than 19-day-old fetuses greater than adults for both brain and liver. Maximal specific binding to cultured neuronal and glial cell membranes was similar (6.2% vs. 7.1%, respectively). [125I]Iodoinsulin cross-linking to the insulin receptor demonstrated that the mol wt (Mr) of the brain alpha-subunit was less than that of the liver alpha-subunit at all stages. [125I]Iodoinsulin cross-linking also demonstrated that the glial cell alpha-subunit (Mr, 130,000) migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis to a position intermediate between the liver (Mr, 135,000) and brain (Mr, 119,000), whereas the neuronal cell alpha-subunit (Mr, 118,000) comigrated with the brain alpha-subunit. In solubilized lectin-purified preparations from brain and liver during development as well as from neuronal and glial cells, insulin stimulated phosphorylation of the beta-subunit. The Mr of the brain beta-subunit, as determined by migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was less than that of the liver beta-subunit. The neuronal cell beta-subunit comigrated with the brain beta-subunit while the glial cell beta-subunit migrated to a position intermediate between the brain and liver beta-subunit. Solubilized lectin-purified preparations from all tissues demonstrated insulin-stimulable phosphorylation of exogenous substrates. From these studies we conclude that 1) functional insulin receptors are present in the brain during development in the rat; and 2) the structural differences demonstrated between neuronal and glial cell and between brain and nonneuronal insulin receptors taken together with previously demonstrated functional differences of the insulin receptor on these tissues suggest a unique function for insulin receptors on neuronal tissues.

Age Factors↗

PubMed1986

Insulin is a growth-promoter of the developing brain: possible implications for the infant of the diabetic mother.

The combination of diabetes mellitus and pregnancy was once associated with significantly increased morbidity and mortality for mother and baby. Advances in the obstetric management of the mother with diabetes and parallel advances in the management of the infant of the diabetic mother (IDM) have lowered the morbidity and mortality in many centers to near those for pregnancies in the non-diabetic woman. A significant increase still exists in the prevalence of congenital malformations in IDMs. Recent animal studies have shown that these malformations are related to maternal hyperglycemia early in the pregnancy, and that if it is controlled with insulin during the critical period of embryologic development, then the malformations may be prevented.

Animals↗

PubMed1985

Developing rat brain binds monoiodinated insulin isomers similarly to other extrahepatic target tissues.

We recently reported a series of binding and metabolic studies which led to the conclusion that the developing rat brain is a target tissue for insulin. Since insulin target tissues (extrahepatic) are capable of differentiating between various monoiodoinsulin isomers, we measured the binding of the B26 monoiodoinsulin isomer compared to the A14 in newborn rat brain preparations to determine if the developing rat brain shared the same relative binding of these isomers (viz. B26 greater than A14) with other extrahepatic tissues. The B26 isomer bound 1.57, 1.50 and 1.34 times as much as did the A14 to brain membranes, glia and neurons, respectively, whereas both isomers were bound equally by liver plasma membranes. Competition-inhibition curves were generated using homologous unlabeled (127I) insulin isomers. Binding of the B26 isomer was greater than the A14 at all concentrations. Scatchard plots showed that the receptor concentrations for the two isomers were similar, and affinity profiles showed that the differences in binding could be accounted for by the greater affinity of the receptors for the B26 isomer. The results indicate that the developing rat brain shares with other extrahepatic insulin target tissues a greater affinity for B26 monoiodoinsulin isomer compared to A14. Future studies of insulin binding should avoid using mixtures of iodinated insulins so that a uniform interpretation of data is made possible.

Animals↗

PubMed1985

Insulin receptors and insulin modulation of norepinephrine uptake in neuronal cultures from rat brain.

Neuronal cells from 1-day-old rat brain in primary culture have been utilized in the present study to characterize insulin-binding sites and a possible action of insulin on these cells. Binding of 125I-insulin to neuronal cultures was 90% specific and time-dependent and reached equilibrium in 120 min. Specific binding was reversible with greater than 90% of binding dissociable within 120 min with a t1/2 of dissociation of 15 min. Various insulin analogues competed for 125I-insulin binding to neuronal cultures according to their known biological potencies. Scatchard analysis of competition data yielded a typical curvilinear plot providing a class of high affinity (Kd = 11 nM) and low affinity (Kd = 65 nM) binding sites. Light microscopic autoradiographic analysis of 125I-insulin bound to neuronal cultures revealed the presence of silver grains predominantly on the neurites with occasional occurrence on the cell soma. Insulin had no effect on neuronal 2-deoxyglucose uptake in contrast with our previous findings demonstrating a 2-fold stimulation of 2-dGlc uptake into astrocyte glial cells from rat brain (Clarke, D.W., Boyd, F.T., Jr., Kappy, M.S., and Raizada, M. K. (1984) J. Biol. Chem. 259, 11672-11675). Incubation of neuronal cultures with insulin caused a dose-dependent inhibition of [3H]norepinephrine uptake with significant inhibition occurring at 1.67 X 10(-11) M. These findings demonstrate that: 1) neuronal cells in primary culture possess specific insulin receptors which are predominantly located on neurites and 2) insulin modulates monoamine uptake in these cultures which suggests that insulin may modulate neural signaling via specific neuronal insulin receptors.

Animals↗