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Somatotropic effects of mammalian growth hormone and prolactin in larval newts, Taricha torosa
GENERAL
AND
COMPARATIVE
ENWCRINOLOQY
18,
391-416
(1972)
NOTES
Somatotropic and
Effects Prolactin
of Mammalian
in Larval
Newts,
Growth Taricha
Hormone torosa
Both mammalian growt,h hormone and prolactin may serve as larval growth hormones in the newt Taridm torow. They promote trunk and tail elongation throughout the enlirc larval period, but growth hormone tends to be more potent, especially on trunk gr0wt.h. in all stages. Prolartin is also antimetamorphic and shows diurnal varixtions in its cffcctiveness as a somntotropin. Growth hormone is not :tntimet:lnlorl)l:i~~ and dew not show the same diurnal variations in somatotropic polency.
In a previous study with larval newts, to~~sw, mammalian growth hormone IGH) was found to be effective in lwomoting body (trunk and tail) growth, whereas prolact,in (PI,) and human placent,al prolactin acted primarily as “antimetamorphic” agents, with little effect on growth per se iCohen et al., 1972). These rcsulte are in cont,rast to findings with sevcsrnl anurans in which PI, is a potent larval ~omatot,rol)in, and GII is relatively inactire in this regard (e.g., Etkin and Gona, 1967; P~rown and Fry?, 1969). Since the .qtudy on newts focusctl primarily on the late larval period and metamoq~horis, the possibility exists that the relative potencies of (:I[ and PT, might tliffrr in earlier stage:: of clcrclol)mcnt. To test this possibility, a wriw of cqwrimentx HIS undcrtnken wit.11 yntmg l:ir\-:tl newts of T. torosn. Tcuichn
MATERIALS
AND
METHODS
T,nrvne awe hatched from eggs collected in a pond near Berkclcy. California and reared at 1s” on brine shrimp. Eggs hatched over a lo-day pwiod starting around March 20. Metamorphosis tlitl not commcncc until late June-early July, whoa it occllrrcd only in the larger animals. Hormone injrctions mere brgun as soon as the larvae :~ppcnrrd large rnouyh to handle (about 34 weeks nft,rr hatching). The conditions for maintaining :md handling animals mere the same as in previous studies with this species (Cohen et al., 1972). Ovine growth hormone (NIH-GH-S9) and ovine prolactin (NIH-PS-S) were a gift of the Endo391 @ 1972 hy
Academic
Prres,
Inc.
crinology Study Section of the S:ttion:d Institutes of Health. Hormones lverc injected every other d:r.v in 5 ~1 of sxlinf,. Injectious were made in the afternoon unless stated otherwise. Attempts were made to uw doses near the minimal effective lrwl: Prcrious csperience show& that 0.1 @g/day WIS marginally effective (Cohen et al., 1972). Cirowth was nsseswd by separate mcnsurements of trunk and tail lengths; botl?- weight lbroved lo tje too vari:lbl(~. RESULTS
AND
DISCUSSION
In the fir& experiment started on April 22, 4 injections (every other day) of 1 pg GH significantly stimulated growth of the trunk ant1 tail, but 1 ,Lg PI, Anulated only tail elongation (Table 1 I. Trunk growth in GH-trcnted animal:: ~-ns significantly greater than in those treated with PL. M7ith 6 injections of 0.5 11gPJ, or GH starting with even smaller animals on June 21 (Table 1; Expt. 21, GH had a highly significant effect, on trunk growth but not on tail growth, and PI, did not nffcct titller rrgion significnntl!-. Roth hormones had the same effect on tail groTTth bllt GH wa,q significantly more effcrtiw on trunk growth. There was no eridrnce of metamorphic rhnnge:: during either of these t1v-ocspcriments. To twt, the possibility thnt the actionS of GH and PL might vary diurnally (i.e., depc~nding on when they were atlmini>tcrcrl), on May 8, each group of animals
” .\lt~:\Il F $1,:. “** ,, < 0.0”. lLkl)t. 1 1v:lh sul~tlividcd into 3 groulw nla;c~lietl fur size :wl 1)rcvious gron.tli. Each grollp continued to receive the same herlllolle trtxtnlellt 3s previously, but, injccticJllr wr(’ given either early (at 090!)), in tlrc nkltlle (1200) or late (1600) in the 12-111’ photoperiod (0730-1930 PST). Control puxtll r:\tcs were the sxne in all three group. and GH continued to be highly effcctiw at all 3 injection times (Fig. 1 ). Tlrew were no significant differences iii total powth rates among tlic three GIItreated groqw. However, the effecticencss of PL \-nricd jvith injection time, being grvntesl earl\- in the tlq and least late in tlw day. ()ni;v the group injected wit,h PI, cnrly iti the clay grew significantly mow tl1n11 col~trols:, and these were not significantly tliffcrcnt from GH-treated animnb in~iwtetl at the same time. The major cliffcrcnce hetn-ten the effect of PL at 0900 21x1 1200 wad on tail growth since trunk growth \va~ identical in these two groul)s. il~(~lll
NJillI)lctWl
\vitlliil
3
Wcdis
ill
43yh
Of
the
:~nd in SO>& of the GH-treated animals; however, only 67% of those treated with PL alone or in combination with GH uontlY~l::
:n]ectlon hrre FIG. 1. Diwnal varintions in the growth (trunk + tnil elongation) in lnrvnl newts trrated with saline (Cant) or 1 pg of prolact,in (PL) or growth hormone (GH) r~rry othrr day between May 8 and May 21 (6 injections). Injections were xivcn at approximately 1.5 (larly), 4.5 (middle) or X.5 (Intc) hnllrs nftrr the onwt, of :I 12-hollr lllloto1vrio~l (Oi30-1030 PST). T1~riicxl t)ws show the III~‘:I*~ antI vc,t~til~ll lirr(,s >II(I\\- 81~:111. l,:krv:lv :iT’,‘r:tgtvl 1.N (‘n1 in Irunli length nnrl 1.2s cm in tail l~wqill :~t 111~ si:rrC of thr c?xperimc,nl
NOTES
3x3
and Licht, 1971). PI, \v:l.- t~~:~(l;l~~ (l~~t(~(~tc.ll in t’lie pituitaries of larval ~;nl:~ni:iudcrs. Anzbystoma tig,+~ror~, but GII :qqwnrccl to be absent (Nicoll and Licht, 1971) Ilowever, both hormones nre detwt:lblc in the glands of larval Kwn cctlesbeicrna ( Olcrnoil.<, 1971). Unfortunately, no infnruxttioll exists on their prcwnre in Inrv:ll lw\vt+ Or nil their secretion wtcs in xtry 3iiil~l~ibinn lnr~nl or adult. It is intl~ortnnt to rcwgnizc the possihilit,y that grow\-th might, 1~swl:tlively ind(q~endeni of tllc l)itiiitxt,!. ill ~otlle urodele Innrae (c g.. ~rwii~worl, 1924; Tnwnvn, 1969). If lnr\.:tl gwwth is inflItcnrc~l 1)~ pituitary hormones ill T. toraw. then the present rcslllts suggest tlrnt tn-o sepnrnte linrinniic~ I i.e.. I)0111C,lf xl111I’T,‘) map lw inr-nlwtl.
C. B., AND Mmx, -1. IT. (1971). lSiurn:d periodicity in the effectiveness of Ilu)l:1(,tin to tallinhibit metamorphosis in Rnna pipic!ls ~)olcs. fl,ue~. Mid/. Natur. 85, 267-271. J-popllysertomy, prolactin and growth of IWF~ml~tamorphic fx,ogs. Gctr. Cons!). EndsIr,, incjl. 13, 126-135. CLE.MONS, G. K. (1971). Changes in growl II h111,mane and prolactin levels in the pituit:ll,y oi frogs dllring variolls physiological and de\ I,ICI~Imc>ntal sinks. M. A. Thesis in Physiology. I-niv. Cnlif.. Pwrlc~lr~y, Calif. COHEN. D. C.. GREENBERG. J. A.. JJCJ-IT. P., 13~11s. H. A., AXD ZIPSER. R.. D. (1972). Growtll :11,11 in the nc’\vt inhibition of metamorphosis 7’arichn (orosn by mammalian hypophysial :lncl placental hormonw. Gcu. Camp. Ejrrlor,. iu~~i. 18, 381-390. f!h’KIN. I\‘.. ASD GONA. -1. (1967). .jnt:lpolli:ltl betwr~n prolaciin and thyroid hormone in :unphilkrn (lctl-c~lopmcnt. J. Eq. Zool. 165, 24% 258. GREENWOOD. A. W’. (1924). The growth of h~,,o.. physcctomizrd salamander larvae. J. Exp. Rj,,l. 2, 75-X. BREAUX,
The illtlic*ntion of :I diurnal wrintion in tllc rr~~mtwc to PI, in the larval newt is (*oitiih:~iit with the recent report of Rrcnus :1u11 >l(G~~r c 1971 j ntl the nnt,imetnmorphic rl’l’(~c~ts of PI, in larvae Rrrnn pipicns and \rit ti otliw rc‘lwrts 011 the actions of PT, 011 grnwtli and fattening in n variety of vcrtrhrntw Mcier. 1969). The effect nf CH. IIO~C~CI‘. ~lors uot a~,twnr to shon tlrc>w1w clillrnnl wrintion. Thlls, since oltr injc~vtinils wrre standardly given in the nftcrnnnn. n-hen the potency of PT, tends to be 5uhninsimn1, the somatotropic effect,8 of GT-I relative to PI, on the newt may he csng~rrntcd. GTT and T’T, hnvc hcen identified as distinrt protein? in thp pituitaries of several urntlrlc rind anltran nml,hihinna OVicoll
394 ~ICOLL.
NOTES c.
s.,
ANI)
LICIIT,
1’.
(1971).
E\.OlUtiOImr)-
Iriolog? of pl~olnctins mtl sornatotropinr;. 11. Eloctm~~l~orelic~ comlmrison of ttltrupod somntotroI&. GVII, Cotup. Il,ntion of hpIlophysc!ctomized newts and newts xilh pituitary scnogrnfis from larval asolotls. ii,r,l~~.sl~~,,Kl l;il-458.
mc.ricat~~m.
The
Effect
J.
of
Stimulation
Exp.
Zool.
Received
in the Lizard,
Califoka
Anolis
Carlcrr
94YH
September
2. 1371 PAUL
171,
Testicular
its
Laboratory of Califorflia
Berkeley,
Hyperthyroidism of
of Zoolvyy wtd
Department Research University
DAVID HOWARD
on the
LICHT
C. COHEN A. BERN
Photoperiodic
Recrudescence carolinensis
IIylwri hywidism in the lizard Auolis carolinensis significantly reduces the stimdilatory r~qonsc of thr, qilicscent testis to increased day length. It is suggested that the lizard thyroid gland may play a role in regulating reproductive cycles.
AND
COMPARATIVE
ENWCRINOLOQY
18,
391-416
(1972)
NOTES
Somatotropic and
Effects Prolactin
of Mammalian
in Larval
Newts,
Growth Taricha
Hormone torosa
Both mammalian growt,h hormone and prolactin may serve as larval growth hormones in the newt Taridm torow. They promote trunk and tail elongation throughout the enlirc larval period, but growth hormone tends to be more potent, especially on trunk gr0wt.h. in all stages. Prolartin is also antimetamorphic and shows diurnal varixtions in its cffcctiveness as a somntotropin. Growth hormone is not :tntimet:lnlorl)l:i~~ and dew not show the same diurnal variations in somatotropic polency.
In a previous study with larval newts, to~~sw, mammalian growth hormone IGH) was found to be effective in lwomoting body (trunk and tail) growth, whereas prolact,in (PI,) and human placent,al prolactin acted primarily as “antimetamorphic” agents, with little effect on growth per se iCohen et al., 1972). These rcsulte are in cont,rast to findings with sevcsrnl anurans in which PI, is a potent larval ~omatot,rol)in, and GII is relatively inactire in this regard (e.g., Etkin and Gona, 1967; P~rown and Fry?, 1969). Since the .qtudy on newts focusctl primarily on the late larval period and metamoq~horis, the possibility exists that the relative potencies of (:I[ and PT, might tliffrr in earlier stage:: of clcrclol)mcnt. To test this possibility, a wriw of cqwrimentx HIS undcrtnken wit.11 yntmg l:ir\-:tl newts of T. torosn. Tcuichn
MATERIALS
AND
METHODS
T,nrvne awe hatched from eggs collected in a pond near Berkclcy. California and reared at 1s” on brine shrimp. Eggs hatched over a lo-day pwiod starting around March 20. Metamorphosis tlitl not commcncc until late June-early July, whoa it occllrrcd only in the larger animals. Hormone injrctions mere brgun as soon as the larvae :~ppcnrrd large rnouyh to handle (about 34 weeks nft,rr hatching). The conditions for maintaining :md handling animals mere the same as in previous studies with this species (Cohen et al., 1972). Ovine growth hormone (NIH-GH-S9) and ovine prolactin (NIH-PS-S) were a gift of the Endo391 @ 1972 hy
Academic
Prres,
Inc.
crinology Study Section of the S:ttion:d Institutes of Health. Hormones lverc injected every other d:r.v in 5 ~1 of sxlinf,. Injectious were made in the afternoon unless stated otherwise. Attempts were made to uw doses near the minimal effective lrwl: Prcrious csperience show& that 0.1 @g/day WIS marginally effective (Cohen et al., 1972). Cirowth was nsseswd by separate mcnsurements of trunk and tail lengths; botl?- weight lbroved lo tje too vari:lbl(~. RESULTS
AND
DISCUSSION
In the fir& experiment started on April 22, 4 injections (every other day) of 1 pg GH significantly stimulated growth of the trunk ant1 tail, but 1 ,Lg PI, Anulated only tail elongation (Table 1 I. Trunk growth in GH-trcnted animal:: ~-ns significantly greater than in those treated with PL. M7ith 6 injections of 0.5 11gPJ, or GH starting with even smaller animals on June 21 (Table 1; Expt. 21, GH had a highly significant effect, on trunk growth but not on tail growth, and PI, did not nffcct titller rrgion significnntl!-. Roth hormones had the same effect on tail groTTth bllt GH wa,q significantly more effcrtiw on trunk growth. There was no eridrnce of metamorphic rhnnge:: during either of these t1v-ocspcriments. To twt, the possibility thnt the actionS of GH and PL might vary diurnally (i.e., depc~nding on when they were atlmini>tcrcrl), on May 8, each group of animals
” .\lt~:\Il F $1,:. “** ,, < 0.0”. lLkl)t. 1 1v:lh sul~tlividcd into 3 groulw nla;c~lietl fur size :wl 1)rcvious gron.tli. Each grollp continued to receive the same herlllolle trtxtnlellt 3s previously, but, injccticJllr wr(’ given either early (at 090!)), in tlrc nkltlle (1200) or late (1600) in the 12-111’ photoperiod (0730-1930 PST). Control puxtll r:\tcs were the sxne in all three group. and GH continued to be highly effcctiw at all 3 injection times (Fig. 1 ). Tlrew were no significant differences iii total powth rates among tlic three GIItreated groqw. However, the effecticencss of PL \-nricd jvith injection time, being grvntesl earl\- in the tlq and least late in tlw day. ()ni;v the group injected wit,h PI, cnrly iti the clay grew significantly mow tl1n11 col~trols:, and these were not significantly tliffcrcnt from GH-treated animnb in~iwtetl at the same time. The major cliffcrcnce hetn-ten the effect of PL at 0900 21x1 1200 wad on tail growth since trunk growth \va~ identical in these two groul)s. il~(~lll
NJillI)lctWl
\vitlliil
3
Wcdis
ill
43yh
Of
the
:~nd in SO>& of the GH-treated animals; however, only 67% of those treated with PL alone or in combination with GH uontlY~l::
:n]ectlon hrre FIG. 1. Diwnal varintions in the growth (trunk + tnil elongation) in lnrvnl newts trrated with saline (Cant) or 1 pg of prolact,in (PL) or growth hormone (GH) r~rry othrr day between May 8 and May 21 (6 injections). Injections were xivcn at approximately 1.5 (larly), 4.5 (middle) or X.5 (Intc) hnllrs nftrr the onwt, of :I 12-hollr lllloto1vrio~l (Oi30-1030 PST). T1~riicxl t)ws show the III~‘:I*~ antI vc,t~til~ll lirr(,s >II(I\\- 81~:111. l,:krv:lv :iT’,‘r:tgtvl 1.N (‘n1 in Irunli length nnrl 1.2s cm in tail l~wqill :~t 111~ si:rrC of thr c?xperimc,nl
NOTES
3x3
and Licht, 1971). PI, \v:l.- t~~:~(l;l~~ (l~~t(~(~tc.ll in t’lie pituitaries of larval ~;nl:~ni:iudcrs. Anzbystoma tig,+~ror~, but GII :qqwnrccl to be absent (Nicoll and Licht, 1971) Ilowever, both hormones nre detwt:lblc in the glands of larval Kwn cctlesbeicrna ( Olcrnoil.<, 1971). Unfortunately, no infnruxttioll exists on their prcwnre in Inrv:ll lw\vt+ Or nil their secretion wtcs in xtry 3iiil~l~ibinn lnr~nl or adult. It is intl~ortnnt to rcwgnizc the possihilit,y that grow\-th might, 1~swl:tlively ind(q~endeni of tllc l)itiiitxt,!. ill ~otlle urodele Innrae (c g.. ~rwii~worl, 1924; Tnwnvn, 1969). If lnr\.:tl gwwth is inflItcnrc~l 1)~ pituitary hormones ill T. toraw. then the present rcslllts suggest tlrnt tn-o sepnrnte linrinniic~ I i.e.. I)0111C,lf xl111I’T,‘) map lw inr-nlwtl.
C. B., AND Mmx, -1. IT. (1971). lSiurn:d periodicity in the effectiveness of Ilu)l:1(,tin to tallinhibit metamorphosis in Rnna pipic!ls ~)olcs. fl,ue~. Mid/. Natur. 85, 267-271. J
The illtlic*ntion of :I diurnal wrintion in tllc rr~~mtwc to PI, in the larval newt is (*oitiih:~iit with the recent report of Rrcnus :1u11 >l(G~~r c 1971 j ntl the nnt,imetnmorphic rl’l’(~c~ts of PI, in larvae Rrrnn pipicns and \rit ti otliw rc‘lwrts 011 the actions of PT, 011 grnwtli and fattening in n variety of vcrtrhrntw Mcier. 1969). The effect nf CH. IIO~C~CI‘. ~lors uot a~,twnr to shon tlrc>w1w clillrnnl wrintion. Thlls, since oltr injc~vtinils wrre standardly given in the nftcrnnnn. n-hen the potency of PT, tends to be 5uhninsimn1, the somatotropic effect,8 of GT-I relative to PI, on the newt may he csng~rrntcd. GTT and T’T, hnvc hcen identified as distinrt protein? in thp pituitaries of several urntlrlc rind anltran nml,hihinna OVicoll
394 ~ICOLL.
NOTES c.
s.,
ANI)
LICIIT,
1’.
(1971).
E\.OlUtiOImr)-
Iriolog? of pl~olnctins mtl sornatotropinr;. 11. Eloctm~~l~orelic~ comlmrison of ttltrupod somntotroI&. GVII, Cotup. I
mc.ricat~~m.
The
Effect
J.
of
Stimulation
Exp.
Zool.
Received
in the Lizard,
Califoka
Anolis
Carlcrr
94YH
September
2. 1371 PAUL
171,
Testicular
its
Laboratory of Califorflia
Berkeley,
Hyperthyroidism of
of Zoolvyy wtd
Department Research University
DAVID HOWARD
on the
LICHT
C. COHEN A. BERN
Photoperiodic
Recrudescence carolinensis
IIylwri hywidism in the lizard Auolis carolinensis significantly reduces the stimdilatory r~qonsc of thr, qilicscent testis to increased day length. It is suggested that the lizard thyroid gland may play a role in regulating reproductive cycles.