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Biomedical subjects

L J Grota

Publications and source records attributed to L J Grota.

At least 55 records · Page 3Linked to original sources
PubMed1979

Plasma corticosterone response to serotonin altering drugs in the 3-day-old rat.

Three-day-old rats were injected with various neurotransmitter altering agents to demonstrate a functional relationship between these drugs and plasma corticoid levels. Plasma corticosterone levels were increased after injection of methiothepin, methysergide, and 5-hydroxytryptophan (5-HTP), but were not changed by cholinergic, adrenergic, and dopaminergic compounds. Imipramine alone had no effects on plasma corticoids but in combination with 5-HTP resulted in a more sustained response than 5-HTP alone. Afunctional relationship between plasma corticosterone and serotonin receptors has been demonstrated in the 3-day-old rat. The presence of this relationship just after birth suggests the possibility that serotonin may be a mediator of early experience effects on later adrenocortical function.

5-Hydroxytryptophan↗
PubMed1979

Role of the pineal gland in diurnal endocrine secretion and rhythm regulation.

The effects of the pineal gland on diurnal endocrine function were studied in male rats. Pineal stimulation by exposure to short daily photoperiods (1L:23D) did not alter plasma levels of testosterone, thyroid-stimulating hormone (TSH) or growth hormone (GH) as compared with those of controls maintained under normal (12L:12D) lighting. Pinealectomy lowered diurnal testosterone levels and increased TSH levels in animals maintained under 1L:23D lighting. Pinealectomy also altered the TSH rhythm and shifted the peak in testosterone levels but did not abolish hormonal rhythms. Active immunization against melatonin and its precursor, N-acetylserotonin (NAS), significantly reduced diurnal androgen levels and elevated TSH levels in animals exposed to short photoperiods, but the 24-hour rhythms persisted. Plasma GH exhibited a diurnal rhythm in animals kept under short photoperiods but GH levels were not affected by any of the above treatments. These data suggest that melatonin and/or NAS may be involved in the maintenance of basal testosterone and TSH levels. The pineal may not be involved in generating hormonal rhythms; however, it may have a role in entraining TSH and testosterone rhythms to environmental lighting.

Animals↗
PubMed1977

Endocrine effects of the pineal gland and neutralization of circulating melatonin and N-acetylserotonin.

Adrenocortical function was studied in rats after shampinealectomy, pinealectomy, or immunization against melatonin and N-acetylserotonin (NAS). Pineals were stimulated to increase melatonin synthesis by blinding or exposure to 23 h of darkness daily. Blinding elevated morning corticosterone levels without altering the corticosterone response to novelty stimulation. Among blinded animals, pinealectomy partially reversed and immunization completely reversed the elevations in morning steroid levels. Exposure to short daily photoperiods flattened the diurnal corticosterone rhythm. Pinealectomy did not affect morning corticosterone levels but reduced evening corticosterone levels. More importantly, immunization resulted in reduced corticosterone levels throughout the diurnal cycle. These findings suggest that melatonin and (or) NAS may be involved in the regulation of resting diurnal adrenocortical function.

Adrenal Cortex↗
PubMed1977

Determination of N-acetylserotonin and melatonin activities in the pineal gland, retina, harderian gland, brain and serum of rats and chickens.

An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens. Anti-NAS and anti-Mel sera were produced by immunization of rabbits with NAS-M-bovine serum albumin (BSA) and Mel-M-BSA, respectively. Anti-NAS serum used in the NAS/Mel RIA reacts equally well with NAS and Mel, while anti-Mel serum used in the Mel/RIA reacts specifically with Mel. The NAS and Mel levels in the pineal and Harderian gland, the retina and the brain of rats and chickens and Mel levels in chicken serum were determined using these RIAs. Levels of NAS and Mel in the rat pineal demonstrated diurnal rhythms with high levels during the dark period and low levels during the light period. The indole levels determined in this study correlate well with those obtained by other methods.

Animals↗
PubMed1977

Effects of neutralization of circulating melatonin and N-acetylserotonin on plasma prolactin levels.

The effect of pinealectomy or immunization against melatonin (Mel) and N-acetylserotonin (NAS) on plasma prolactin (Prl) levels was studied in rats following pineal stimulation induced by blinding or exposure to short photoperiods (1 h light and 23 h darkness daily). Blinding alone or together with pinealectomy or immunization did not alter resting Prl levels or the response to novelty stimulation. Exposure to short photoperiods flattened the diurnal Rrl rhythm seen in control rats kept in 12 h of light and 12 h of darkness daily. Pinealectomy slightly lowered Prl levels but did not affect the diurnal rhythm. Immunization caused a significant reduction in Prl levels, although the diurnal Prl rhythm persisted. These data suggest that Mel and/or NAS may be involved in the maintenance of basal Prl levels.

Animals↗
PubMed1977

Characteristics of antibody produced during chronic treatment with LHRH.

In a patient with hypogonadotropic hypogonadism treated with luteinizing hormone releasing hormone (LHRH), secondary failure of both subjective and hormone responses occurred at the time of appearance of binding of 125I-LHRH by the patient's serum. On electrophoresis of the patient's serum with 125I-LHRH, label was found only in the gamma globulin region. 125I-LHRH added to the patient's serum was precipitated by sheep anti-human immunoglobulin G (anti-IgG) but not by sheep anti-human immunoglobulin M (anti-IgM). Competitive displacement of 125I-LHRH by unlabeled LHRH was demonstrated while TSH releasing hormone (TRH), somatostatin and rat pituitary hormones showed no displacement when tested at concentrations 5 X 10(6) greater than that of LHRH. Studies using 14 different analogs of LHRH revealed that those with changes at the carboxy terminus showed binding similar to LHRH. It is concluded that IgG antibody to LHRH was produced in this patient by repeated administration of synthetic LHRH. It is further concluded that antibody specificity is directed toward the N terminus region.

Antibodies↗
PubMed1977

Epileptogenic action of intraventricularly injected antimelatonin antibody.

In rats, intraventricularly injected antimelatonin antibody caused the appearance of transitory epileptiform abnormalities. Epileptic activity arose from and was limited to the cortical mantle of the hemisphere ipsilateral to the injection side. The occasional occurrence of lateralized seizures has also been observed. Control injection of saline, of the vehicle (rabbit serum), or of antibody saturated with melatonin induced flattening and desynchronization of the electroencephalogram but not epileptiform activity. Repeated antimelatonin injections caused reappearance of the same type of epileptic abnormalities that lasted slightly longer than the first time. Melatonin may play an inhibitory role in neuronal excitability.

Animals↗
PubMed1976

Immunohistological investigation of N-acetylserotonin in the rat cerebellum after parachlorophenylalanine treatment.

The amount of N-acetylserotonin (NAS) in the granule layer of the rat cerebellum was investigated using immunolohistologic double antibody technique. After 5 days of treatment with parachlorophenylalanine (PCPA) an increase of NAS was observed. The possibility of a differential effect of PCPA on serotonin synthesis in the neurons and the nerve terminals is discussed.

Animals↗
PubMed1976

Effects of early experience on the metabolism and production of corticosterone in rats.

Rats were handled for 3 min daily for 3 weeks before or after weaning or were left totally undisturbed. At 80 days of age, animals from each group were selected for corticosterone half-life determination. Adrenal tissue from thr remaining animals was incubated in vitro in the presence or absence of ACTH. Handled and unmanipulated animals did nto differ in half-life or in adrenocortical output. These data do not support the hypothesis that the reduced adrenocortical reactivity that results from manipulating animals is due to either the metabolsim of corticosterone or the response of the adrenal cortex to ACTH.

Adrenal Cortex↗
PubMed1976

Gonadal effects of pinealectomy and immunization against N-acetylindolealkylamines in the hamster.

In order to determine whether circulating melatonin (MEL) is necessary for the gonadal regression seen in hamsters exposed to a short photoperiod, animals were immunized with N-acetylserotonin (NAS) conjugated to protein. Antibodies formed against this conjugate bind MEL and NAS equally. When exposed to a short photoperiod (L:D, 1:23), a dramatic regression was seen in gonadal weight with no effect on body, Harderian gland or adrenal weight. Plasma testosterone levels also dropped. Immunization against NAS did not modify these effects, suggesting that circulating MEL does not mediate the antigonadal effect of the short photoperiod.

Animals↗
PubMed1976

Immunohistochemical localization of melatonin in the rat Harderian gland.

Using fluorescence and double antibody techniques, melatonin was localized immunohistologically in the secretory cells of the Harderian gland of mature male rats. The presence and quantity of melatonin in the acinar cells seem to correlate with the amount of porphyrins inside the lumen. The specificity was proven by disappearance of yellow fluorescence after saturation of antibody with melatonin or after use of nonspecific antibody only.

Animals↗
PubMed1976

Antibodies to catecholamines.

The haptens p-tyramine and synephrine were conjugated to bovine serum albumin by means of the formaldehyde condensation reaction. These conjugates were emulsified in adjuvant and injected into rabbits. Antiserum was harvested at 10-day intervals after booster injections. The anti-sera were screened by immunodiffusion. After detecting the presence of antibody, an antiserum was further characterized by antiserum dilution curves, standard curves, and cross-reactivity studies using labeled p-tyramine or labeled metanephrine. The cross-reactivity studies indicated that the antisera to either hapten had low affinity to compounds with structural deviations on the side chain or ring other than at the position ortho to the phenolic hydroxyl group. The antisera were more sensitive to 3-methyoxylated compounds (3-methody-tyramine and metanephrine) than to 3-hydroxy or unsubstituted compounds.

Antibodies↗